It's unfortunate that the National Electrical Code uses the term grounding and grounded. I was a member of the NEC section for many years and there has always been confusion. Many of us believe that the current terminology should be canned and use the terms earthing and bonding to help eliminate confusion. Many other countries use this terminology and it is much simpler.
@@honumoorea873 The metric system is soo much easier than the imperial system. I have a degree in chemistry so I have been using the metric system since the 1950s. It is great. I can't even imagine trying to do scientificl calculations in the imperial format. That being said, the imperial system is so ingrained into our culture that I can't see it being changed in the foreseeable future. Need a calculator that converts metric/imperial/fractions. What a mess.
Fault current travels back to the source, not to the earth. Mike Holt’s Grounding versus Bonding videos are great source of information. I have to stay up with the NEC every 3 years. He has been teaching for over 40 years. As a side note Will, if it was not a stand alone system, or if you were to use this system for a home back up in an emergency power outage, through an interlock kit, make sure your Neutrals and Grounding conductors will be separated in this Square D panel. 6/4 cable would go back to the interlock breaker. Also, only one neutral conductor is allowed per terminal. Otherwise you will have an objectionable currents flowing on all metal parts of your electrical system - dangerous condition to have. I keep finding this in people’s homes when someone would add a sub panel. The grounding and grounded (neutral) conductors have to be connected only in one point in the house - at the main breaker panel.
Very good point if I use an interlock kit. I would absolutely separate the grounds and neutrals in the panel. That would be very dangerous if I did not. I am glad you watch Mike Holt! He is fantastic!
I was going to bring up bonding. I know in a city connection you only bond at the main breaker box and not at the subpanels. As I understand the concept of bonding is to give the electricity a return path so as to not ground out an entire system, how does that work in an off grid scenario? Do you still do bonding at the main box? Or is it a ground that is used? This is a great discussion going on here and bringing up very good points that I was curious about.
I'm trying to figure out my solar system sure glad I found the videos thank you Will. I'm taking in so much information trying to figure out what stuff to buy and everything. It's overwhelming and now I'm finding out about grounding and it's really overwhelming I don't know anything about it.. and even your great explanation I couldn't figure out. On my new system that's similar to this one but I'm only going to have one inverter for now 120. I'm not going to have any AC input because I don't have any AC input anywhere I'm completely off grid. I was considering wiring my generator into that AC input. I guess I still don't know anything about grounding. I'm going to have to listen to the video again and again. I think you said if you have AC input you don't need ground because it's already in the AC input wires that sounds logical. I'll read it again if my comment doesn't make any sense I'll delete it.. I didn't know anything about grounding until today. Wow it's very confusing.
Your videos are a wealth of infomation , thanks for taking the time to educate us newbies , I specialy appreciate your approach to saftey and in depth explanations .You helped me build my first off grid sep up for my cabin few years ago and its still going strong . Keep up the awesome work mate !!
The comprehensiveness of this video makes it a true standout. I have struggled to explain my particular situation, and I now understand that I need to describe other situations that would require earth grounding, how and why may be the missing piece. Truly excellent work!
I built my own system and I’m totally confused, it always works better when you show exactly how you’re hooking up a ground and where and why! 😳 I’ll definitely look into the links. Thanks
May I also suggest NFPA 99 ... just skim contents for meat ya want.... things will start to click and looking into the subject as you said will help us all be safer : )
Quite simply do not do this you do not know what you’re doing if you can’t understand technical language here it means you can’t understand the physical concept either you should really consult regulations
I'm just a layman on the subject but I'm glad your warning people about adding extra grounds. The grounds all have to be bonded together at the same potential otherwise you are giving lightning a dangerous path through your home. Edit: also ground bonds need very heavy wire or flashing and short runs to be effective from my understanding.
I have now watched the video. Surge protection is a wonderful idea on the DC side - do not oversize it, match it closely to the maximum open-circuit potential of the solar array. Get the ground connection wired as straight as possible to a good earth ground (and this can be separate from the service entrance - like at a ground-mounted array) but bonded to other ground rods if inside a structure. You are correct in not adding more ground points than at the service entrance of a building. Ground loops are to be avoided, chased down, and eradicated. They can cause all kinds of obscure issues. An SPD will not cause a ground loop. The DC side, being under 60 volts, is likely going to be a Class 2 circuit under the National Electrical Code (NEC) Solar arrays have the advantage of being inherently current-limited. Batteries are not, so over-current protection is required. Neither are going to be much of a shock hazard at 48 VDC. thanks!
Your knowledge of electrical code is impressive, James Alles. I felt like a first-year electrical student, again, just reading your comment. Are you an instructor?
@@jayspell179 no, that is something that I missed. I became aware of the low-voltage aspect of the code working for Simplex on Fire Alarm systems in the 80s. I suppose I did do a little teaching. thanks
I enjoyed reading your comments. What happens when the PV arrays are wired in series and produce voltages of around 400V DC? The latest solar inverters can take up to 6kW input @450V DC up to 20A. If I had two 5000W inverters wired in parallel and eight 50V Canadian solar panels (VOC 49.6V, IOC 13A) wired in series serving each inverter, what might be the earthing / grounding implications of such an install?
@@fredflintstone1428 earthing / grounding stays the same. Conductor insulation becomes critical - 600V is needed. check your local codes, it is now high voltage, and an entirely different animal.
Great videos, I learn a lot. Grounding is a complex topic. I don't have the answers but I have some thoughts. NEC 250.32 deals with grounding outbuildings. Since 2008, grounding electrodes are required at outbuildings like your garage causing multiple earth grounding electrodes contrary to the older philosophy of avoiding ground loops in the grounding conductor systems.
One more thing you need to understand about AC grounding is "Bonding" this provides a path for the electricity to trip the breakers from a grounded short circuit. Bonding is usually provided by a ribbon in the back of your breaker box that goes from ground to neutral. If you have multiple boxes, only bond your ground to the neutral in the box closes to the incoming service and remove the bonding connection in all boxes feeding the main box. Make sure grounds are in place to all wiring to other boxes. This provides only one path for a large surge or lightning.
Part 2 Grounding Update: ua-cam.com/video/X3QA9T_O1g0/v-deo.html Update: this system will never pass an inspection and never needs to. It is Offgrid and there is not a single permit required for connecting a battery to an inverter, and using a couple of panels laying on the ground. People are trying to reference NEC?? Why? This inverter isn't even listed. Sure it's compliant and certified, but it would still fail inspection. And that's fine. I'm not connected to grid (besides back up battery charger which isn't grid tie. It's a battery charger). And I only care about safety and that's it. Original pinned comment: Oh and I'm adding ac supply at the input on it's own breaker today (and programming it to only use the battery charger. Not bypass!). That's why I said it has true earth ground in one of my given examples. When this system is supplied by a true earth ground ac circuit, I do not need to separate the grounds and neutrals on my panel because the transfer switch will be open, and the output of this inverter will not act as a sub panel supply. This is because the input only supplies a battery charger in my configuration. If I am using it as a UPS (which requires programming it as such), and I have a large dedicated breaker supply from my sub panel, (which I will not do), then I will need to separate ground and neutrals. That would make a separate connection, and it is not isolated. When the ATS inside the inverter is connected only to the battery charger, it is isolated. But still susceptible to high voltage if a ground loop was created. If it was not grounded when not connected to ac input, that is fine. There are plenty of standalone systems without grounding. Such as an RV electrical system with inverter when not connected to shore power. Same thing. So it really depends on how you use it. If you are using it not as a solar power system, and instead as a stand-alone UPS, then I could see why you do not want to bond the ground and neutrals at the ac output. But that is the only exception I can think of. ~~~~~~~~~~~~~~~~~~~~~~~~~ Does off-grid solar confuse you? Check out my DIY friendly website for solar system packages and product recommendations, and so much more! www.mobile-solarpower.com Join our DIY solar community! #1 largest solar forum on the internet for beginners and professionals alike: www.diysolarforum.com Check out my best-selling, beginner-friendly 12V off-grid solar book (affiliate link): amzn.to/2Aj4dX4 If DIY is not for you, but you love solar and need an offgrid system, check out Tesla Solar. Low prices and great warranty, and they can take your entire house offgrid with their new Powerwalls: ts.la/william57509 ~~~~~~~~~~~~~~~~~~~~~~~~~ My solar equipment recommendations (Constantly updated! 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Will, are you sure the setting for utility charging vs ups really switches the neutral? A switched neutral tends to be fairly expensive and I’d be surprised if this kind of sophistication is built it. I would have guessed the neutrals (AC in and out) were always bonded to each other. Would be interesting to test this with a multimeter.
I think of a UPS as when the solar/battery is a backup for the grid. The other option - and what I'm thinking of doing in my setup is to have solar/battery as the primary with the grid as the backup. I believe that if I'm doing it in that way that I have to have a dedicated ground for the AC subpanel which is going to be in a solar shed/out-building ... I've slept a time or two since I delved into the NEC looking this stuff up though - I'm going to have to re-read it to remember the details on grounds and panel bonding however.
@@kmil2010 actually some are not. You always need to check. These inverters are for Offgrid use only when not in ups or backfeed mode. They have some inverters that are hybrid, and the connections are obviously different. But yes I should verify with multimeter
Thanks for these great videos! We just bought a 12 kw system on Sat for our off grid home and these videos couldn't have come at a more opportune time!
Thank you Will for expounding on this ground discussion going on on your site. I have learned a lot from Mike's lecture and from your comments. Now I need to go unhook my ground rod from my array!! This is way more complicated than most people think especially when you add in lightning.
Are you sure you want to do that? I don't think what he is saying is the same as a grounded array. if you put up a tv antenna outside I'm sure you would ground it. if lighting hit the array it will most likely enter the ground at the grounded array
Mike Holt is great. I used to use his videos in my Electrical Trades Classes. For those people on here that want drawings, they should go look at Mike Holt. He does great drawings.
Good information. Appears that sub panels need to have isolated neutrals so faults go back to main panel. Grounding electrodes for lighting protection.
Is that considered a sub panel since it is all by it's self? Or a "main panel"? I was wondering if it would need to have separate neutral and grounding bars.
Perfect!!! If anyone disagrees with anything he said here go back and listen to it over and over and then study electrical engineering and electrical theory and you will then understand that everything that was said is spot on. Thank you Will.
On the subject of grounding. I have seen varying opinions on whether or not to ground the PV Array (I mean the PV frame NOT ground to inverters etc.) to Earth Grounding rod. You may want to do a video on this.
I'd love a video on that, I'm off grid, and run a 12v dc system with a only on when in use 3000w stand alone inverter, I'm still clueless as to whether an earth electrode is needed on the AC side can someone please explain, do I earth my solar controller? Or do I bond these to negative, battery etc?
Code requires separate grounding electrodes for sub panels in outbuildings. You bring across 4 wires from the primary panel to the sub (L1, L2, N, GND), and you do not bond GND to N at the subpanel. That is to avoid current loops. But the remote subpanel DOES get it's own grounding electrode which is then connected to the ground bus bar in the sub panel and the ground pulled from the primary. A subpanel adjacent to the primary panel does not require its own grounding electrode, because the path to the primary is so short. So the question here is how far away is that sub panel from the primary. Even IF in the same building.
The sub panel in this situation is feef from the inverter. It's not a sub panel of the grid connected system. The only ground connection between this system and the grid feed system will be with the grid supplied feed to the inverter, if and when that happens.
Excellent, and I fully agree (see 0:50). Approx quote: Even if you have two or three Grounding Electrodes you want to tie it together at one place'. Many absolutely stand by the fact that there can only be ONE Grounding Electrode period! They have no understanding of what Single-Point Grounding actually means! Many even think grounding attracts lightning which is directly opposed to sound engineering practices.
Will, be very careful discussing marine "grounding" as it can get tricky and lead to ALOT of corrosion for any metal touching the water. Stray current for marine is a big deal.
@@gregoryyount6907 And every boat is different. Wood, fiberglass, steel or aluminum hull and composition of below water line hardware. Then you have “under protected, over protected and the just right. Where will it spend most of the time fresh, salt or brine. Types of anode metals, bond or not to bond and bond to what? Neutral switch over to ground, isolation transformers, equipment current leakage. Oh the list goes on. It’ can be a science. Wrong gets expensive. And land electricians think they got it rough Lol!
Check out the victron unlimited PDF for some basic marine grounding advice: www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf ABYC and this book is where I get my info on marine systems from: www.amazon.com/Boatowners-Mechanical-Electrical-Manual-4/dp/0071790330/ref=asc_df_0071790330/?tag=hyprod-20&linkCode=df0&hvadid=312176357948&hvpos=&hvnetw=g&hvrand=3157251246000314898&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030754&hvtargid=pla-333901114316&psc=1&tag=&ref=&adgrpid=60258871137&hvpone=&hvptwo=&hvadid=312176357948&hvpos=&hvnetw=g&hvrand=3157251246000314898&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030754&hvtargid=pla-333901114316
Excellent points, however, in places as Florida which has more than a million lightning strikes yearly it is very important to have lightning dissipators the bigger and more the better to make the system invisible to electrons Flying in both directions.
@@veryinteresting591 Central Florida was where I grew up! First off of OBT down the road from Gator Land and then out in Clermont. Looking back it was intense!
Excellent! I feel slightly responsible! Something I didn't realize when watching other vidy (off grid title?) that you had an earth ground elsewhere. Absolutely correct, grounds loops are dangerous and can cause electrical problems with certain equipment. Bottom line, follow local code, mfg instructions. Any exposed conductive surfaces that encloses a potential (voltage) should be PROPERLY grounded to prevent shock. exceptions like double insulated code etc, ya need to check code. And yea, seen double insulated fail. And my apologies, didn't realize you DID have a proper grounded case (breaker box) enclosure.... thought off grid. Thanks, Ken
That was important to note that you had an established ground elsewhere already. I would also consider 110.26 as a good practice(batteries below equipment)
Hello! Thank you so much for you video! I was able to find this because I just recently built a portable solar generator. I have 4s lifepo4 and 1000w inverter. I tried running in the inverter at around 400 to 500w. I touched the busbars on the battery to see if it is heating up or not but at my surprise, I got shocked! I am still clueless as to why this happened
Unless you are using a single load against inverter, you want to have everything properly grounded possibly with GFCI. Otherwise a fault somewhere can cause ground loop and what would be grounded is e.g. a hot wire - then all what should be ground is suddenly "hot" against the earth, and this becomes a very dangerous setup. This is not a theoretical example, I touched a place which should be true ground on friend's off-grid powered house, then kept swearing for several minutes, then spend hours to debug how the hot wire got shorted to the ground - the root cause was a mouse chewing the wire insulation, where the wire came to contact with steel rod to basement, and so far, all ground over the house was suddenly hot against the earth.
I haven't watched the video yet. 1. *Lightning protection.* a system is more likely to survive if it is isolated from ground. 2. *Safety Ground* The protections of grounding an appliance chassis can now be handled by the newer technology of a Ground Fault Circuit Interrupter (GFCI). I will not be grounding my system, as any 120VAC load will run through some type of GFCI. I do the same for portable engine/generator sets. If anyone's system is to be installed permanently on a structure, building codes may apply depending on the jurisdiction. Your Authority Having Jurisdiction (AHJ) trumps anything I just said.
System with isolated neutral (ungrounded neutral), or IT system, will have different behaviour, than normal system with grounded neutral. Especially, if it fitted with GFCI's. IT electric systems are used in industry, and must have special electronic equpment to control wire insulation integrity and resistance (relative to ground). Also, these systems requires to use 2-pole breakers - for both phase and neutral conductors. And this is not compatible with standard US domestic distribution panels. So, in order to stay within Code, it is easier to use standard system with grounded neutral. Even, if this system is completely independent from AC grid, except grounding "network" within household (grounded service neutral + local grounding rods or Ufer grounding + connections to various tubes, like water mines).
One more thing you need to understand about AC grounding is "Bonding" this provides a path for the electricity to trip the breakers from a grounded short circuit. Bonding is usually provided by a ribbon in the back of your breaker box that goes from ground to neutral. If you have multiple boxes, only bond your ground to the neutral in the box closes to the incoming service and remove the bonding connection in all boxes feeding the main box. Make sure grounds are in place to all wiring to other boxes. This provides only one path for a large surge or lightning.
I have a Xantrex Freedom Sw 3012 inverter charger, 4-6 volt batteries and two 160 watt solar panels. How much more solar power can I add to this setup. Thanks and Keep up the great work.
Absolutely you never want two earth ground with one system for the ground loop reasons you stated. I did not realize you had an AC input from your house. Many inverters will bond the neutral to the input AC when they switch to line power. Does the AC input ground common to your solar ground? If so you may want on oversized ground wire back to your house and it’s ground rode. Thanks again for your great videos.
I'm looking to disconnect my utility and have an inverter run my house, the inverter has the earth and neutral bonded at its output, i would like to run the inverter inplace of utility at the panel so would i have to remove the ground rod? It's confusing me.
2000w SunGoldPower inverter charger fed from my house 120v, and from 3 X 100w solar panels. All feeding 4 X 100ah LiFePo4 batteries. House is earth grounded. What I hear you saying is that I should remove my earth ground on my solar panels ASAP?
Will, your title indicates this video is about OFF GRID SYSTEMS ONLY yet you continually talk about AC inputs. If you have AC inputs then it is not off grid. How about another video about true off grid systems with NO AC input at all.
A local grounding to your own earth spike would make sense in case of an outage of commercial power, which would cause you to lose their ground reference. But in such a case, you’d also need to have an Earth-Neutral Bridge (the single point where it’s all bonded), which flips automatically between commercial power ground and your own local ground, depending on if the commercial provider is up or down. Surge protection on for each fuse box on the PV side is definitely a plus. I use 500V SPD’s.
No... loss of utility input does not interrupt earth grounding at the meter. Only way to interrupt that would be to disconnect the earth conductor feeding the ground rods at the residence ot the pole.
@@SuperVstech Not my experience… I have SMA PV inverters, and every time we had a loss of mains AC, we had a PE (potential earth) fault that caused the inverters to stop making power because they assumed grid failure, even with the micro grid present. An Earth-Neutral bridge bonding that also included a local ground spike fixed this.
@@DJMT-Africa If there wasn't a neutral to earth ground bond at the the main disconnect, then that was your problem, and it would have been in violation of code. Downstream panels/subpanels from that point onward must have their grounds and neutrals separated, unless it falls under some exception.
The NEC requires you to bind neutral and ground on the secondary of a separately derived system (transformers, solid state inverters, etc.). The reason for this is because the primary and secondary are physically separated, therefore the grounding connection does not transfer. You should bind the primary and secondary grounds (exclude the primary neutral because it is bound with the ground upstream).
But what if the Secondary is NOT connected to the onshore grid panel? if you add a ground (no longer free floating) then you may create a ground loop or have a gradient problem even though you may not think they will transfer. 30 sec and 5 min portion of this video.
Bonding Will, everything that is not the earth connection is a bond, not a ground. We use grounded bus bar in large incoming, high voltage vaults, as well as places like server roms to bond equipment to earth.
I can see adding a ground rod only if this is for an off grid 120VAC or a 120/240VAC system. In this case, it would be the only ground rod. Otherwise, you are correct, 1 ground rod at the service entrance only when connected to a grid-tie system. But, what if you are using a 120VAC inverter in combination with a relay that redirects the load back to grid when the inverter turns off? The grid side is grounded, but the inverter side would not be. I have several of these systems, and I tied all my grounds together on each one. This grounds the inverter cases and the inverter output.
It's amazing to me how many people misunderstand the purpose of earth ground. Mostly people seem to think that earth ground protects them from getting shocked somehow. Lack of "earth" ground doesn't mean you don't have a ground at all, it's just not tied to earth. Your ground wire still acts as an emergency return path to the breaker box to trip the circuit breaker if needed, but that ground wire doesn't need to be tied to earth to perform that duty. By not having an earth ground you're actually decreasing the chance of being shocked. Since the "earth" you're standing on is no longer a conductor you can no longer get shocked by simply accidentally touching a hot wire because there is no "return path" through the earth for that current to flow through your body. In fact: a common piece of safety equipment used by crews working in outdoor / wet environments is something called an "isolation transformer". It's a 1:1 transformer (So it doesn't step up or down) that plugs into a wall socket and creates a new electrical connection that creates an "isolated" electrical path that is no longer referenced to ground. This is used as a piece of safety equipment because by removing the earth ground as a return path for the current it makes it safer to use electrical equipment outdoors in wet conditions. Off grid inverters achieve the same result as an isolation transformer. They effectively "isolate" the electrical system from earth.
Circuit breakers are overcurrent devices, and will not trip on a ground fault that isn't overcurrent. Please fix your comment. This isn't worded accurately: "Your ground wire still acts as an emergency return path to the breaker box to trip the circuit breaker if needed..."
As a counterpoint, not bonding to earth ground your system ground can float significantly above or below earth ground. You will then become a path for that equalization. Usually it's under a hundred volts and very little current BUT it can get crazy in certain situations. This effect is one of the big reasons we all ground to Earth and don't encourage floating ground.
@@FrancisKoczur Circuit breakers aren't designed to trip on "ground faults" at all in any circumstance. In fact a "ground fault" would make a circuit breaker *less likely* to trip because a "ground fault" generally means the return path is compromised in some way. The purpose of the "ground" wire in a circuit is to provide an "low resistance" emergency return path to the breaker box. The "low resistance" piece is key to this. By providing a low resistance return path if the hot wire were to come loose and touch the metal case of an appliance the low resistance return path would ensure the breaker trips as many amps would instantly flow through that return path. A "ground fault", by definition, is a condition where this return path is removed or damaged, which would prevent the breaker from tripping and would create a shock hazard if the hot wire in an appliance become loose, frayed, etc. Circuit breakers do not protect against ground faults unless they are GFCI type circuit breakers. GFCI protects against ground faults, circuit breakers do not. Either way the situation does not change based on whether your ground is tied to earth or not. The low resistance return path from the appliance to the breaker box is what's important, not whether or not the breaker box ground is also attached to earth.
@@oshavlfarms7239 As a counter counterpoint: Every time someone uses a portable generator, or one installed in an RV or truck, or any kind of mobile/portable inverter such as one installed in any kind of vehicle, they are utilizing a floating ground. Think about how many thousands of people are using one of these floating ground devices every day from long haul truck drivers who aren't allowed to idle their engines and yet no-one seems overly concerned about the danger. That's because the amount of charge buildup on these smaller scale systems is not very large. Even if there was a significant voltage differential of 100+ volts: it would be the same as touching a tiny capacitor which was charged to that same voltage. The reason why it's not a big danger is because it would result in a microscopic amount of current flow and it's large amounts of current, not voltage, that is dangerous. With something as massive as the grid that's a real concern, and which is why it's earth grounded. But with a small off grid system it just isn't.
I have a question, is that gray power panel a main panel or a sub panel? As a main I have no problem with it,just it has no main shutdown in it. If it’s a sub panel the grounds and neutral should be separated not bound together. What you are saying is right, one grounding point in the main panel box. But you can have more than one ground from that main box. Hear we have to have at less two a two ground rods or a ground rod and be bounded to the water pipes.
Will, Great point. A similar question relating to those solar generator/power stations. I believe they are not truly grounded. The A/C output runs on floating neutral. What if, when the A/C charge input is connected. Would the power station be grounded during the time through the A/C input cable? Now, would the ground pass through to the A/C output if there were output load plugged in the A/C output jack?
Great presentation and explanation! Keep up the great work and posting videos you're saving equipment and you're definitely saving people for some nasty shocks.
Please provide some visualization on this topic. I have seen an end to end Inverter/Electric Sub-panel/Battery setup video and the gentleman there grounded the whole system with a true grounding electrode. Basically a separate grounding bus bar in the subpanel which is connected to inverters as well as true ground electrode outside.
You are a wealth of knowledge in solar generation systems. However, this video was like another language. I’m sure the more advanced people could follow all you said. Me, not so much. I do understand ground to some degree. I understand how earth ground rods and such work with AC electricity. I was looking for help with the correct way to protect my small 4 panel system. My concerns are lighting protection for the panels. How and if I need to ground the wiring. How to connect my inverter to ground. That sort of thing. I will search your other videos. Thank you….
I appreciate this info. I'm 100%off grid and I was curious if I should have a earth ground connected. I bought a grounding rod but have never hooked it up. I felt like it was a complete closed system and didn't believe I actually needed one.. I have a 5kw eco-worthy hybrid inverter. Connected to my camper breaker box. I also have a inverter generator hooked up to my system to charge/bypass also I have 12 solar panels.. so... Should I use my ground rod?? Thank you
On my steel boat, I have a separate 24V lithium battery just connected to my mpp 3k inverter charger. I run the DC bus floating, with a 1 meg ohm resistor between the minus and the central grounding point. This way, I have the added safety of a floating system, and prevent static charge from building up on my DC bus. All Protective Earth conductors end in a central grounding point connected to the hull, just behind the isolation transformer. Shore power Earth is connected to a parking connection on the isolation transformer. When the boat is on the hard the shore power earth must be connected to the hull to prevent having a large steel structure that is unbonded. Marine Electrics in a Nutshell.
Hello Will, I have just discovered your videos and will be devouring them over the next while. Thank you for posting them! I have a situation that as a non - electrician has me confused, and I am hoping maybe you might have an answer for me. I am currently in the California desert in my solar powered cargo trailer/RV conversion. I am an astrophotographer, and spend my winter far out in the desert looking for dark skies. I have 4-325 watt Panasonic solar panels on the roof and 3-300 amp hour Lifeblue batteries for 900 watts total. The charge controller is a Midnight 150, and the charger/inverter is a Magnum 2000. The system was originally installed in my 5th wheel RV about 6 years ago by a very reputable solar company that specialized in RV installations. They have moved on and no longer do installations on RVs, so I can't talk to the people who actually installed it. I recently moved the solar system from the 5th wheel RV to the current cargo trailer/RV conversion. Grounding to earth in an RV is not practical of course, and nothing on the solar system has been grounded to the frame. I had read that the panel, inverter, and charge controller should all be grounded to the frame, yet they weren't by the original installers. The team that installed my system had installed solar systems in about 3000 other RVs before mine, so I doubt if they just "forgot" to ground the solar components to the frame. I have to think it was intentional. So when I moved the system to the current trailer, I didn't ground anything either. So far all is working great, with 4 120 volt and 4 12 volt circuits. Only the fridge 120 volt circuit is not on a GFCI. My 120 volt Samsung home fridge specifically says not to put it on a GFCI protected circuit. So my question is probably obvious: Should I be grounding anything to the frame of the RV? I used all metal outlet boxes, and they are all on internal walls. The outlet, and the box itself are grounded with a pigtail to the ground wire that goes back to the panel. As a non - electrician, I have a hard time understanding why I would ever want to send electricity into the metal frame of an RV. This seems crazy to me, and a recipe for a serious shock. It seems like I now have a closed electrical loop with the panel. Why would I want to send electricity to the frame of the RV, under any circumstances? As an aside, when I was a kid I stepped off a poorly grounded RV just after the rain had stopped. The step was metal, and I was barefoot and wet. I can only remember screaming and being frozen in place for a second or two before passing out and fortunately falling away from the step and breaking the ground. For a few hours I couldn't walk, and both my ankles were really sore. Within a few more hours I was fine. I suspect it would have killed me in a few more seconds if I had not passed out and broken the connection. It was a really terrible experience, and I don't want to relive it because I made a grounding error. But intentionally sending electricity into the RV frame just seems like the last thing I would want to do. Isn't an electrified RV frame what shocked me in the first place? Any advice much appreciated!
Just installed an axpert max 7.2kw, and as soon as it switches some internal relays while powering on, the house goes dark. Had to remove the input ground wire for it to run. Im assuming the inverter switches the neutral to ground internally 🤷♂️ In the manual it states the pv array must not be grounded to it as well..
Seems a bit over complicated ... my understanding of what I think I heard ... a panelboard/breaker box (out of your inverter) should always be tied to an earth ground. You may choose to earth ground the metal case of your outdoor solar panels for lightning protection. However, do not earth ground your solar panel output/PV supply to your charge controller. It's okay to surge protect the PV supply, but again, do not earth ground it. Is that accurate?
Its code to bond all electrical equipment including what you have there. Yes you should have only 1 point of ground but everything is required to be bonded.
@@networkingdude For me , as a retired HVAC guy . All this is getting a little more confusing . After watching the video Will provided a link for , actually destroys almost all that we learned about the " reason " for a " earth ground " , and WHY . We were told that the " bare ground " for equipment was to make a short to ground on the equipment , safer for anyone who might touch it otherwise ?! We were never told about anything about two " earth grounds " creating a loop , and back feeding " if you will " and destroying other equipment ?! I still question though , that if those rods are far enough apart , that would happen ? I am actually still confused about " where " in that system , Will has a earth ground ? Does the load ( A/C unit ) have a earth ground ? Plus , a lot of that video refutes what I was told by a Master , who was in our shop . Though , all that was Pre 99 . I did my HVAC classes mostly tween 78 - 88. Glad I am retired now :D
@@indycharlie He stated that he was going to be adding utility input to the inverters, and that will be grounded to the service entrance. That is the earth ground for the inverters and therefor the system. He hasn’t installed that yet which is why it may be hard to visualize with what he is saying. Also, you need earth ground when dealing with utility service because that’s how the grid is grounded. In an isolated system it only needs its own ground. Think of it like a car, which is its own isolated electrical system. There is no earth ground, but everything is “grounded” through the negative terminal. An off-grid system is similar in this case.
@@coryvincent6249 First off . I am about to turn 71 , and have been retired since 06 . When I retired I was the " work leader " in a HVAC Shop on a AFB . I had 22 guys coming to me daily about trouble shooting , and other issues . We also did Controls . Electromagnetic , pneumatic , and finally DDC. My days were filled with answering questions , attending meetings on remodeling of Bldgs , New buildings , and studying NEW equipment manuals & data . I am not trying to scarf myself here . But when I retired after 31 yrs . I said I would never read another Tech Manual , ever again . So , between my age , and WANTING to forget it all . Including what I knew about the NEC . My thoughts may be wrong . But , I still see no way that on this " isolated " system , as he installed it . That there is a place anywhere to a " earth ground " . Are you saying he is bringing in a " Public Utility " into the inverters ?! So , is he putting in a manual disconnect for that public utility ?!? Part of this " might " be the Language used at all the AF schools I attended at Sheppard AFB ?! DOD was a weird animal , in this regard . Yes , I understand a 12 V DC car . But he is using 120 / 240 VAC single phase . And from what I was taught , and remember . That " isolated system " would need a " earth ground " that is for ( as we were taught ) a safety , so a short would take that path , and NOT use you . But hey , I never installed a system that was " isolated " from the Public Utility , at any of the AFB's I worked at . Thanks for the reply to this old , tired , X VN combat medic . Have a good one . PLEASE DON'T LET MY CONFUSION , CONFUSE ANYONE ELSE , READING WHAT I HAVE SAID .. LISTEN TO "" WILL "" .... . ..... Gubs
I agree completely, but I heard rumors for questionable sources that a Tesla charger might be very finicky in this type of circut. I was hoping to see how that worked out today. Great tutorial thanks.
More explanation on the ac input please, as this is off grid, are we assuming the ac input is a generator with its own true earth (rod) and does it have a men link?
May sound stupid but someone could ground this system using a low resistance power resistor as a shunt system, so as to not cause the inverter a complete short circuit and blow mosfets but make it possible to have a return ground path in case a short happens in the device or local code demands you ground the system. The other option is a seperate ground with no bonded neutral just to dissipate static buildup.
My growatt inverter specifically addresses this in the manual where I have to have an inverter controlled relay to bond and unbound my ground to neutral on the inverter output specifically when it switches back to grid power. Perhaps you can do a video on this?
I suppose, that this relay acts as "automatic grounding relay" for the following reason. Inverter itself can be considered as independent AC source, like gasoline/diesel generator. So, if this inverter is in Off-grid mode (island mode) without any connection to AC grid, then, its output neutral must be grounded. If inverter has AC grid connection, AND its neutral runs from AC input to AC output continuously, without any interruptions like contacts of relays, then, neutral grounding of AC output is accomplished by AC grid's already grounded neutral. Following yours descriprion of Growatt behavior and need for specially controlled relay, I think, that neutral from inverter's AC input to AC output can be breaked by some internal relays in island mode. So, this relay is needed to groung output neutral locally, near the inverter itself. The same requirements for output neutral grounding are exists in the world of Telecom inverter systems (DC 48 V to various AC voltages). We also need to ground AC output neutral in case of absence AC input connection to AC grid.
@@WillProwse I run solar as my primary and the grid as my backup. The grid neutral and ground are bonded in the main panel. So when I'm running in grid mode all loads function normally. When the batteries charge up and it switches back to the inverter my loads stop functioning because the neutral and ground output of the inverter are not bonded. By code I can only have 1 neutral to ground bond in the system. If I connect neutral to ground on the inverter output without a relay I end up with 2 bonds when it switches back to the grid. The growatt has normally open and normally closed wire connections for this exact purpose to control a bonding relay.
Yep, @john, it's a requirement in my country, when the inverter operate on battery, neutral must be connected to ground. Mppsolar inverter don't do that. Shutdown ac input and check the voltage between neutral and ground. Should be zero, but its not on mppsolar inverter. You can find a grounding box, wich is simply a relay that connect neutral to ground under a condition controls by the inverter optional relay output. Need a special firmware version to activate the relay when ac input is not present. Otherwise you can implement the same thing with voltage detection on ac input and some relay. The thing is mppsolar is totally speechless about grounding to neutral regarding regulation and theirs products.
Hey Will, can you do a video where you show everything and anything you need to do a off-grid solar charging setup for an electric car to charge at full level 2 charging? I can charge my Nissan leaf at 6.6kw with my grid tied chargepoint charger. The charger is plugged into a 50 Amp, 240 Volt Nema 6-50 outlet. Thanks and sorry if there is already a diy video for this. I would like to put solar on my garage and then have the entire garage be off-grid also.
This now raises my own questions. Is it possible I can send you a YT link to a video of my setup with my current ground configuration, get your feed back?
Hi Will, I have a cuestion? I install a inverter powmr is 230, 24v 3000W off grid when I check the power in the output lines, one give me 90v and the other line 170. I conect the ground I install a ground route outside the storage.
Very interesting stuff about the "ground loop". And I have a question. My house has a ground for the sockets (with those metal rods in the ground at the corner of the house) and a separate ground (another metal bar at the opposite corner of the house, as it happens...) for the tv cable. Is that wrong? I am assuming the shield on the antenna plug at the tv is connected to the power ground. Maybe not. Am I in danger? Thanks!
Electrical codes should require all the grounding rods to be "bonded" together (i.e., there should be a direct ground wire connection between all grounding rods, which should also be no further than 16 feet apart). You mention the bus bars are on opposite sides of the house, but that's probably fine as long as they share the same grounding rod or the grounding rods are properly bonded. If you want some piece of mind, you could trace the connection leaving the TV cable bus bar and check that it connects back to the service ground.
Grounds need to be bonded at the rods. Delicate electronics are not where bonding should occur. If the potential of your antenna ground is better than your ac ground, your entire/most of home grounding system will attempt to pass through your tv. By bonding the rods, both should have nearly equal potential and surge/emf (why you need a coax ground) will go to shortest path vs path of least resistance.
What a great community! Thank you all for trying to help me understand this better. The antenna ground is something I did myself to get rid of EMF interference and I can tell you that is NOT connected to the mains ground. But I do wonder if TVs will connect the mains ground to the antenna ground (shield). I need to do some better research on this. Also, this is in Europe, on a 240V connection. Some things (codes) might differ.
One more detail: the cable tv on my house (which goes to multiple tv sets) is NOT coming from outside the house. There is a fiber coming in with both internet and digital tv signal and it goes to this box that outputs internet and cable tv...
One thing I haven't seen in any solar vids on youtube is do you ground to your chassis in a pickup truck caps house battery solar setup with inverter that's not tied into the start battery
I'm not sure how you run ground in the states, but the ground we use if for fault current return and has nothing to due with lightning strikes, that's what lightning arrestors are for. In most cases using the M.E.N. system (multiple earth neutral), the main earth is tied into the neutral conductor. Any metallic enclosure has to be earthed so that if a fault occurs with an active conductor to frame it will trip the circuit breaker, and any fault that occurs through a person to ground trips the R.C.D. (residual current device). However having said that we also have other earthing systems other than M.E.N. such as the Direct Earthing System, The E.L.C.B. System (Earth Leakage Circuit Breaker) (voltage operated type), and the S.W.E.R. (Single Wire Earth Return) that uses only one wire and the ground is the neutral return system. I found what you were trying to say a little confusing but that may be attributed to different terminology used. But basically yes, the earthing conductor is used for return fault currents and has nothing to do with lightning. Our supply authorities use a three phase system for reticulation and distribution, generally delta to star step down transformers where the centre point of the star connection is the neutral connection which can also be earthed. Nice watching albeit a little confusing.
Great video, but I had a question about these inverters. I went on their website and found that these are “off grid” inverters. What is this “AC input” that you refer to in your video? Is that for AC charging?
They have many types of inverters, I think the ones Will has are "hybrid". You have 120V in from the grid yes. That can be used to carry loads or charge batteries when the solar array isn't producing. You can choose what power to use for the load side of the inverter... give priority to the solar and batteries or the grid etc... depends what your goal is. Lots of people just use these things as a type of online UPS for critical circuits and the batteries are just there if the grid fails. One of the inverters cuts out the need for transfer switches and is flexible on where it gets energy ... arrays, generators, the grid - everything but rubbing two sticks together. I've powered/charged mine with a step up transformer using the dual alternators in my truck (36V @50amps step up)
Depends on what type you buy. I have these hybrid off grid inverters and I can use it completely off grid with a generator as a back up or connect it to the grid if the battery bank is depleted and no sun.
I do have my panels on their own grounding for the panel frames and dc lines are fused incase something tries to send more amps through the dc input lines like a failed shorting inverter that backfeds ac to the panel frames.
Hey Will. Very informative videos! I’ve watched many of your videos on lithium batteries but I wondered if you have reviewed later generation lead acid batteries called crystal lead batteries? Not as good as LiFePO4 but reportedly much improved on flooded lead acid batteries. Could they be a low budget option worth considering?
You can have multiple ground rods as long as they are all connected with heavy wire (6 AWG) or copper strap. That will eliminate any voltage potential between the separate circuits they are connected to. Eight ft. rods should be spaced 16 ft. apart.
You need to get a NEC code book! A supplemental ground rod is only required when the 1st measures over 25 ohms. Then a 2nd one 6ft from the 1st. An inspector will never question if he see's two ground rods spaced 6ft apart.
The larger the connector cable to the source from the output board, the smaller the earth fault loop impedance, making it trigger faster under fault conditions. You are correct, you wouldn't want to connect to a house earth system, some (most) do not have sufficient equipotential bonding and this allows for transient currents on the earth conductor, and we are not just talking milliamps.
Thanks Will. Not many people talk about grounding system for the solar system and I’m glad you did. I plan to install a Growatt SPF 5000ES hybrid off grid solar inverter in my RV Bus in Bangkok, with Lifepo4 battery bank, and solar panels. This inverter will take solar power or take AC shore power to charge batteries and convert battery DC to 220Vac output to power Dometic Aircon and TV, etc. So here, I have input ground terminal when I take 220Vac shore power. My question is do I need to connect output ground for the AC output or should I leave it unconnected (open) ? If it is needed, where would this AC ground connected to in the vehicle ?Hope you could help explain.
I see you have two DC fuse blocks but you don't talk about if they are fast or slow blow. and if you are going to use a fast blow fuse it could help mitigate the need for a true ground. another reason you could want a true ground is power feedback from your AC or 220v/240v power tools that don't just turn on/off clean.
Personal Opinion, obviously the argument for/against grounding on these internal components is open for discussion, but I believe there is something to be said for earth grounding exterior things like panels and heat-pumps/condenser units. These are what can/will build up a potential (static charge) and so will increase the likelihood of a lightning strike. Once a strike occurs, IMO no realistic amount of grounding will really protect that equipment.
Lightning protection is best done via lightning rods, which have their own dedicated earthing conductors not to be shared with anything, as the lightning will travel down it, which then yes produces a gradient voltage across anything it touches, including dirt. The house grid earth connection is there in case the earth connection at the pole transformer is lost, the connection to earth is maintained, via the bonded neutral (both at the pole transformer and the house mains panel). The neutral-to-ground "bond" is there for fault current to travel back up the neutral to the power source, tripping the circuit breaker on the hot controlled conductor. This conductor is the ground pin on a wallsocket, it also neutralizes the live voltage during a fault so that humans don't get shocked. Some SPD's just happen to use one or both to achieve surge dissipation, which is fine. The neutral should only ever conduct the operational current, which is also flows back to the power source tripping the breaker during normal operation. It may or may not also conduct fault current by happenstance. There should only be one earth connection point and the ground should never be used to carry any operational current, this also prevents voltage gradients from damaging equipment. If you have properly installed lightning rods there shouldn't be a need for array SPD's, other than perhaps static discharge. A direct hit will render just about anything dead regardless of how good the SPD is designed or believed to be. Some inverters are single phase, some are split-phase, some have bonded neutral and some don't, all of which adds extra complexity for DIY'ers. If anyone is unsure then they should just contact a certified electrician to do the work, it might save their life and/or not burn their whole city to the ground. (and code compliance and all.)
Excellent video, Will. A question: Let's assume you were NOT connected to an AC input with an earth-connected ground and were truly grid independent. Would you then connect your breaker panel to a true earth ground? I assume so. The reason I ask is that some people might have a system whereby they are *sometimes* connected to an AC input with earth-connected ground (tiny house on wheels connected to extension cord) but sometimes they are off grid with no AC input. Would you have to disconnect and reconnect an earth ground to this breaker panel depending on if AC input is available?
There is the argument that on some devices, static accumulation can cause a shock if not connected to true earth. I have never experienced it before. Having a floating system, not connected to earth at all, is not necessarily dangerous. I'm still trying to find devices that can accumulate charge as I've read from multiple sources. I test for potential in the cases of my equipment and have never found it. Besides that, I don't see any issue having a floating system.
We have a old lead acid off grid system. Way before all this new stuff. Just had a lightning bolt fry our inverter last night. Guess it's time to switch over!
I have read many comments and happy to see so much interest and concern over safety and desire to become more educated on it. Please do so! One of the issues, imo, is our words.... take ground, neutral and line. We all use ground" wrong at times. Many times I say ground when I mean desired return current path, which in houses is called the neutral.... which is (typically) strapped at the box to earth ground. And speaking of ground loops with myself and other saying how they are bad... when the electric company safely has created ground loops with your neighbor's earth ground rod.... all depends on where the loops are. I'm happy to see these discussions : ) Use Good sense... Common sense? def common these days... might not be the best! An example of a play with words intentionally when the understanding of "common sense" to make good decisions is not properly conveyed. Same as more recent technical words like ground etc... Will does good with follow up and education, ya'll do the same now, ya hear?
It's a year later, but here is how adding additional electrodes (ground rods) works. You can add as many as you want, anywhere, but they must be bonded underground (i.e. 2/0 copper or bigger), and you can space them up to 10 ft apart. The OP is talking about adding a standalone ground rod that is not tied together underground and is most likely more than 10 feet away. That isn't good.
I wonder what qualifies as a large pv array? I have 13kw array and not sure if I need an SPD to an earth ground (8' copper electrode I reckon). This system is off grid if that makes a difference
The panel needs to be tied to an earth ground and technically according to National Electrical Code, you should NOT bond Neutral and Ground in a sub panel. Neutral and Ground SHOULD be bonded in your primary panel ONLY , as you want to earth ground and Neutral bonded in only one place as you are saying. In this system, I don't think there is a primary street power feed, it seems to be only powered by the batteries. So in this case if I am correct about the AC inputs not being present, it is a gray area sort of... The only other thing I see is the use of temporary wiring meant for extension cords. The NEC requires Romex, or equivalent vinyl jacketed wire designed for permanent installations in homes vs the rubber jackets used in temporary (extension cord) wire which is what I think you have used here. When you add the AC inputs, I would recommend running the two conductor with ground (Black/White/ground), with the ground wire going to the earth ground in your feeder panel (assuming it is your primary panel and not a sub-panel) and bonding it to the earth ground input on the inverters and the panel. Or you could run a single ground from your main earth ground in your main panel right to the earth ground on the inverter distribution panel. Then un-bond the neutral and earth in the inverter panel so everything is connected to your one earth ground on your main panel., they looked like they were bonded in there but can't tell for sure. The earth ground is primarily for all of the stuff you will be running AC from the panel, but my inverter has an earth ground connection and I would think the MPP does as well. As a safety concern, many items are designed not turn on if there is no earth ground present, such as tesla charging for instance.
NEC doesn't well adapted to presence of additional independent power supplies at household: it was written with only a grid connection in mind. So, grounding on inverter's neutral will strongly depend from individual system's scheme. If inverter(-s) system is completely independent from AC grid, like Will's system from this video, then neutral must be grounded right after the inverter, in first distribution panel. Or, which preferable, it must be grounded at inverter's output terminals. In case of several inverter units in parallel/split phase configuration - it is better to create a neutral busbar for collection (combining) neutrals from all inverters. This busbar will be the point of neutral grounding. This busbar must be installed close to inverters.
So, I have my 110v from the service panel on the pole to my inverter then off to the RV. The solar panels are mounted on top of a metal utility trailer. The panels are all connected with ground clamps and wire. WHERE do I put the ground wire from the panels? The panel at the pole is earth grounded. Thank you
You are conflating neutral bonding with grounding. The neutral is bonded to ground at ONE point only. Ground does not carry ANY current when done properly and there is no limit to it's attachment to earth. For example, all metal within 5' of water is required to be electrically bonded to earth, a/k/a ground. This includes rebar, plumbing, metal framing, windows, doors, screen enclosures, etc. Some of these items, such as copper pipe and rebar, may be buried in the earth and serve as a ground path. Again, there is no limit to points of contact with earth for bonding and more is better, but all of them MUST be tied together. This is all covered in the NEC manual which you are required to comply with.
Will, can you please give us a visualization of different grounding procedures? Correct vs incorrect. Grid tie vs off grid.
seconded
Thirded
fourthed
Ditto
Same, please
It's unfortunate that the National Electrical Code uses the term grounding and grounded. I was a member of the NEC section for many years and there has always been confusion. Many of us believe that the current terminology should be canned and use the terms earthing and bonding to help eliminate confusion. Many other countries use this terminology and it is much simpler.
I agree! I prefer using the term earthing, but I know that's not the appropriate term. It's unfortunate the terminology can be so confusing.
Good to know.
It needs to go! Those who know will pick up on the changes it fast enough. The rest of that don’t can start learning properly.
@@honumoorea873 The metric system is soo much easier than the imperial system. I have a degree in chemistry so I have been using the metric system since the 1950s. It is great. I can't even imagine trying to do scientificl calculations in the imperial format. That being said, the imperial system is so ingrained into our culture that I can't see it being changed in the foreseeable future. Need a calculator that converts metric/imperial/fractions. What a mess.
@@pauloconnell7668
that is dumb, grinding your axe in a grounding thread
@will do more grounding vidoes. Start from the beginning. Been searching so few videos on this.
Fault current travels back to the source, not to the earth. Mike Holt’s Grounding versus Bonding videos are great source of information. I have to stay up with the NEC every 3 years. He has been teaching for over 40 years. As a side note Will, if it was not a stand alone system, or if you were to use this system for a home back up in an emergency power outage, through an interlock kit, make sure your Neutrals and Grounding conductors will be separated in this Square D panel. 6/4 cable would go back to the interlock breaker. Also, only one neutral conductor is allowed per terminal. Otherwise you will have an objectionable currents flowing on all metal parts of your electrical system - dangerous condition to have. I keep finding this in people’s homes when someone would add a sub panel.
The grounding and grounded (neutral) conductors have to be connected only in one point in the house - at the main breaker panel.
Very good point if I use an interlock kit. I would absolutely separate the grounds and neutrals in the panel. That would be very dangerous if I did not. I am glad you watch Mike Holt! He is fantastic!
I was going to bring up bonding. I know in a city connection you only bond at the main breaker box and not at the subpanels. As I understand the concept of bonding is to give the electricity a return path so as to not ground out an entire system, how does that work in an off grid scenario? Do you still do bonding at the main box? Or is it a ground that is used? This is a great discussion going on here and bringing up very good points that I was curious about.
I'm trying to figure out my solar system sure glad I found the videos thank you Will.
I'm taking in so much information trying to figure out what stuff to buy and everything. It's overwhelming and now I'm finding out about grounding and it's really overwhelming I don't know anything about it.. and even your great explanation I couldn't figure out. On my new system that's similar to this one but I'm only going to have one inverter for now 120. I'm not going to have any AC input because I don't have any AC input anywhere I'm completely off grid. I was considering wiring my generator into that AC input. I guess I still don't know anything about grounding. I'm going to have to listen to the video again and again. I think you said if you have AC input you don't need ground because it's already in the AC input wires that sounds logical. I'll read it again if my comment doesn't make any sense I'll delete it.. I didn't know anything about grounding until today. Wow it's very confusing.
Please do a video on grounding considerations for solar panels on both roof mounted and ground mounted arrays.
Your videos are a wealth of infomation , thanks for taking the time to educate us newbies , I specialy appreciate your approach to saftey and in depth explanations .You helped me build my first off grid sep up for my cabin few years ago and its still going strong .
Keep up the awesome work mate !!
The comprehensiveness of this video makes it a true standout. I have struggled to explain my particular situation, and I now understand that I need to describe other situations that would require earth grounding, how and why may be the missing piece. Truly excellent work!
I built my own system and I’m totally confused, it always works better when you show exactly how you’re hooking up a ground and where and why! 😳
I’ll definitely look into the links. Thanks
May I also suggest NFPA 99 ... just skim contents for meat ya want.... things will start to click and looking into the subject as you said will help us all be safer : )
Quite simply do not do this you do not know what you’re doing if you can’t understand technical language here it means you can’t understand the physical concept either you should really consult regulations
I am confused. A diagram would have been nice to include in the video. The lightning diagram alone taught me a lot!
I'm just a layman on the subject but I'm glad your warning people about adding extra grounds. The grounds all have to be bonded together at the same potential otherwise you are giving lightning a dangerous path through your home.
Edit: also ground bonds need very heavy wire or flashing and short runs to be effective from my understanding.
I have now watched the video.
Surge protection is a wonderful idea on the DC side - do not oversize it, match it closely to the maximum open-circuit potential of the solar array. Get the ground connection wired as straight as possible to a good earth ground (and this can be separate from the service entrance - like at a ground-mounted array) but bonded to other ground rods if inside a structure.
You are correct in not adding more ground points than at the service entrance of a building. Ground loops are to be avoided, chased down, and eradicated. They can cause all kinds of obscure issues. An SPD will not cause a ground loop.
The DC side, being under 60 volts, is likely going to be a Class 2 circuit under the National Electrical Code (NEC)
Solar arrays have the advantage of being inherently current-limited.
Batteries are not, so over-current protection is required.
Neither are going to be much of a shock hazard at 48 VDC.
thanks!
Your knowledge of electrical code is impressive, James Alles. I felt like a first-year electrical student, again, just reading your comment. Are you an instructor?
@@jayspell179 no, that is something that I missed. I became aware of the low-voltage aspect of the code working for Simplex on Fire Alarm systems in the 80s. I suppose I did do a little teaching. thanks
Wow I don't think I'm ever going to be able to figure out these grounding theories.🙂
I enjoyed reading your comments. What happens when the PV arrays are wired in series and produce voltages of around 400V DC? The latest solar inverters can take up to 6kW input @450V DC up to 20A. If I had two 5000W inverters wired in parallel and eight 50V Canadian solar panels (VOC 49.6V, IOC 13A) wired in series serving each inverter, what might be the earthing / grounding implications of such an install?
@@fredflintstone1428 earthing / grounding stays the same. Conductor insulation becomes critical - 600V is needed. check your local codes, it is now high voltage, and an entirely different animal.
Great videos, I learn a lot. Grounding is a complex topic. I don't have the answers but I have some thoughts. NEC 250.32 deals with grounding outbuildings. Since 2008, grounding electrodes are required at outbuildings like your garage causing multiple earth grounding electrodes contrary to the older philosophy of avoiding ground loops in the grounding conductor systems.
One more thing you need to understand about AC grounding is "Bonding" this provides a path for the electricity to trip the breakers from a grounded short circuit. Bonding is usually provided by a ribbon in the back of your breaker box that goes from ground to neutral. If you have multiple boxes, only bond your ground to the neutral in the box closes to the incoming service and remove the bonding connection in all boxes feeding the main box. Make sure grounds are in place to all wiring to other boxes. This provides only one path for a large surge or lightning.
Part 2 Grounding Update: ua-cam.com/video/X3QA9T_O1g0/v-deo.html
Update: this system will never pass an inspection and never needs to. It is Offgrid and there is not a single permit required for connecting a battery to an inverter, and using a couple of panels laying on the ground. People are trying to reference NEC?? Why? This inverter isn't even listed. Sure it's compliant and certified, but it would still fail inspection. And that's fine. I'm not connected to grid (besides back up battery charger which isn't grid tie. It's a battery charger). And I only care about safety and that's it.
Original pinned comment:
Oh and I'm adding ac supply at the input on it's own breaker today (and programming it to only use the battery charger. Not bypass!). That's why I said it has true earth ground in one of my given examples.
When this system is supplied by a true earth ground ac circuit, I do not need to separate the grounds and neutrals on my panel because the transfer switch will be open, and the output of this inverter will not act as a sub panel supply. This is because the input only supplies a battery charger in my configuration. If I am using it as a UPS (which requires programming it as such), and I have a large dedicated breaker supply from my sub panel, (which I will not do), then I will need to separate ground and neutrals. That would make a separate connection, and it is not isolated. When the ATS inside the inverter is connected only to the battery charger, it is isolated. But still susceptible to high voltage if a ground loop was created.
If it was not grounded when not connected to ac input, that is fine. There are plenty of standalone systems without grounding. Such as an RV electrical system with inverter when not connected to shore power. Same thing.
So it really depends on how you use it. If you are using it not as a solar power system, and instead as a stand-alone UPS, then I could see why you do not want to bond the ground and neutrals at the ac output. But that is the only exception I can think of.
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Will, are you sure the setting for utility charging vs ups really switches the neutral? A switched neutral tends to be fairly expensive and I’d be surprised if this kind of sophistication is built it. I would have guessed the neutrals (AC in and out) were always bonded to each other. Would be interesting to test this with a multimeter.
You are right. I really enjoy your Channel.
Ciao
I think of a UPS as when the solar/battery is a backup for the grid. The other option - and what I'm thinking of doing in my setup is to have solar/battery as the primary with the grid as the backup. I believe that if I'm doing it in that way that I have to have a dedicated ground for the AC subpanel which is going to be in a solar shed/out-building ... I've slept a time or two since I delved into the NEC looking this stuff up though - I'm going to have to re-read it to remember the details on grounds and panel bonding however.
Hi, could you please make a new video with "schemas" and explanation? It will be very clear for all of us. Please.
@@kmil2010 actually some are not. You always need to check. These inverters are for Offgrid use only when not in ups or backfeed mode. They have some inverters that are hybrid, and the connections are obviously different. But yes I should verify with multimeter
Title says does my “offgrid” need a ground but you are saying it has ac input. What if there is no ac grid input then what?
Thanks for these great videos! We just bought a 12 kw system on Sat for our off grid home and these videos couldn't have come at a more opportune time!
Thank you Will for expounding on this ground discussion going on on your site. I have learned a lot from Mike's lecture and from your comments. Now I need to go unhook my ground rod from my array!! This is way more complicated than most people think especially when you add in lightning.
Are you sure you want to do that? I don't think what he is saying is the same as a grounded array. if you put up a tv antenna outside I'm sure you would ground it. if lighting hit the array it will most likely enter the ground at the grounded array
Mike Holt is great. I used to use his videos in my Electrical Trades Classes. For those people on here that want drawings, they should go look at Mike Holt. He does great drawings.
Good information. Appears that sub panels need to have isolated neutrals so faults go back to main panel. Grounding electrodes for lighting protection.
Is that considered a sub panel since it is all by it's self? Or a "main panel"? I was wondering if it would need to have separate neutral and grounding bars.
Great job explaining the shock hazard. Also GFIC breakers are a great way to save your life. All my shop outlets are fed buy GFIC breaker.
Perfect!!! If anyone disagrees with anything he said here go back and listen to it over and over and then study electrical engineering and electrical theory and you will then understand that everything that was said is spot on. Thank you Will.
On the subject of grounding. I have seen varying opinions on whether or not to ground the PV Array (I mean the PV frame NOT ground to inverters etc.) to Earth Grounding rod. You may want to do a video on this.
Oh good idea. Some panels, specifically CIGs, should never be grounded. That would be an interesting video.
I'd love a video on that,
I'm off grid, and run a 12v dc system with a only on when in use 3000w stand alone inverter, I'm still clueless as to whether an earth electrode is needed on the AC side can someone please explain, do I earth my solar controller? Or do I bond these to negative, battery etc?
Code requires separate grounding electrodes for sub panels in outbuildings. You bring across 4 wires from the primary panel to the sub (L1, L2, N, GND), and you do not bond GND to N at the subpanel. That is to avoid current loops. But the remote subpanel DOES get it's own grounding electrode which is then connected to the ground bus bar in the sub panel and the ground pulled from the primary. A subpanel adjacent to the primary panel does not require its own grounding electrode, because the path to the primary is so short. So the question here is how far away is that sub panel from the primary. Even IF in the same building.
The sub panel in this situation is feef from the inverter. It's not a sub panel of the grid connected system. The only ground connection between this system and the grid feed system will be with the grid supplied feed to the inverter, if and when that happens.
Excellent, and I fully agree (see 0:50). Approx quote: Even if you have two or three Grounding Electrodes you want to tie it together at one place'. Many absolutely stand by the fact that there can only be ONE Grounding Electrode period! They have no understanding of what Single-Point Grounding actually means! Many even think grounding attracts lightning which is directly opposed to sound engineering practices.
Will, be very careful discussing marine "grounding" as it can get tricky and lead to ALOT of corrosion for any metal touching the water. Stray current for marine is a big deal.
Very true
Yeppers, sacrificial anodes is an interesting subject for others who are curious about this. Best
This is an area where even qualified marine technicians can get it wrong. Be very cautious about offering advice.
@@gregoryyount6907
And every boat is different. Wood, fiberglass, steel or aluminum hull and composition of below water line hardware. Then you have “under protected, over protected and the just right. Where will it spend most of the time fresh, salt or brine. Types of anode metals, bond or not to bond and bond to what? Neutral switch over to ground, isolation transformers, equipment current leakage. Oh the list goes on. It’ can be a science. Wrong gets expensive.
And land electricians think they got it rough Lol!
Check out the victron unlimited PDF for some basic marine grounding advice: www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf
ABYC and this book is where I get my info on marine systems from: www.amazon.com/Boatowners-Mechanical-Electrical-Manual-4/dp/0071790330/ref=asc_df_0071790330/?tag=hyprod-20&linkCode=df0&hvadid=312176357948&hvpos=&hvnetw=g&hvrand=3157251246000314898&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030754&hvtargid=pla-333901114316&psc=1&tag=&ref=&adgrpid=60258871137&hvpone=&hvptwo=&hvadid=312176357948&hvpos=&hvnetw=g&hvrand=3157251246000314898&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030754&hvtargid=pla-333901114316
Excellent points, however, in places as Florida which has more than a million lightning strikes yearly it is very important to have lightning dissipators the bigger and more the better to make the system invisible to electrons Flying in both directions.
Can confirm, had my house growing up struck twice and the street a ton of times.
I can also confirm. Central Florida has widespread lightening almost every day. It’s unreal.
@@veryinteresting591 Central Florida was where I grew up! First off of OBT down the road from Gator Land and then out in Clermont. Looking back it was intense!
Thank you for the video report.
Excellent! I feel slightly responsible! Something I didn't realize when watching other vidy (off grid title?) that you had an earth ground elsewhere. Absolutely correct, grounds loops are dangerous and can cause electrical problems with certain equipment.
Bottom line, follow local code, mfg instructions. Any exposed conductive surfaces that encloses a potential (voltage) should be PROPERLY grounded to prevent shock. exceptions like double insulated code etc, ya need to check code. And yea, seen double insulated fail.
And my apologies, didn't realize you DID have a proper grounded case (breaker box) enclosure.... thought off grid.
Thanks,
Ken
I did not understand that either . If it was said during the video . I missed it . Be safe out there folks ... Gubs
That was important to note that you had an established ground elsewhere already. I would also consider 110.26 as a good practice(batteries below equipment)
Would like for you to test or give your opinion on the EMP Shield product to protect your equipment from pulse power surges.
Hello! Thank you so much for you video! I was able to find this because I just recently built a portable solar generator. I have 4s lifepo4 and 1000w inverter. I tried running in the inverter at around 400 to 500w. I touched the busbars on the battery to see if it is heating up or not but at my surprise, I got shocked! I am still clueless as to why this happened
Unless you are using a single load against inverter, you want to have everything properly grounded possibly with GFCI. Otherwise a fault somewhere can cause ground loop and what would be grounded is e.g. a hot wire - then all what should be ground is suddenly "hot" against the earth, and this becomes a very dangerous setup. This is not a theoretical example, I touched a place which should be true ground on friend's off-grid powered house, then kept swearing for several minutes, then spend hours to debug how the hot wire got shorted to the ground - the root cause was a mouse chewing the wire insulation, where the wire came to contact with steel rod to basement, and so far, all ground over the house was suddenly hot against the earth.
I haven't watched the video yet.
1. *Lightning protection.* a system is more likely to survive if it is isolated from ground.
2. *Safety Ground* The protections of grounding an appliance chassis can now be handled by the newer technology of a Ground Fault Circuit Interrupter (GFCI).
I will not be grounding my system, as any 120VAC load will run through some type of GFCI. I do the same for portable engine/generator sets.
If anyone's system is to be installed permanently on a structure, building codes may apply depending on the jurisdiction.
Your Authority Having Jurisdiction (AHJ) trumps anything I just said.
System with isolated neutral (ungrounded neutral), or IT system, will have different behaviour, than normal system with grounded neutral. Especially, if it fitted with GFCI's. IT electric systems are used in industry, and must have special electronic equpment to control wire insulation integrity and resistance (relative to ground). Also, these systems requires to use 2-pole breakers - for both phase and neutral conductors. And this is not compatible with standard US domestic distribution panels. So, in order to stay within Code, it is easier to use standard system with grounded neutral. Even, if this system is completely independent from AC grid, except grounding "network" within household (grounded service neutral + local grounding rods or Ufer grounding + connections to various tubes, like water mines).
One more thing you need to understand about AC grounding is "Bonding" this provides a path for the electricity to trip the breakers from a grounded short circuit. Bonding is usually provided by a ribbon in the back of your breaker box that goes from ground to neutral. If you have multiple boxes, only bond your ground to the neutral in the box closes to the incoming service and remove the bonding connection in all boxes feeding the main box. Make sure grounds are in place to all wiring to other boxes. This provides only one path for a large surge or lightning.
Technically one grounding rod will not comply with NEC. You can have many as long as they tied together.
I have a Xantrex Freedom Sw 3012 inverter charger, 4-6 volt batteries
and two 160 watt solar panels. How much more solar power
can I add to this setup. Thanks and Keep up the great work.
Absolutely you never want two earth ground with one system for the ground loop reasons you stated. I did not realize you had an AC input from your house. Many inverters will bond the neutral to the input AC when they switch to line power. Does the AC input ground common to your solar ground? If so you may want on oversized ground wire back to your house and it’s ground rode. Thanks again for your great videos.
I'm looking to disconnect my utility and have an inverter run my house, the inverter has the earth and neutral bonded at its output, i would like to run the inverter inplace of utility at the panel so would i have to remove the ground rod? It's confusing me.
Can you make a for dummies version of this.
2000w SunGoldPower inverter charger fed from my house 120v, and from 3 X 100w solar panels. All feeding 4 X 100ah LiFePo4 batteries. House is earth grounded. What I hear you saying is that I should remove my earth ground on my solar panels ASAP?
I've never analyzed the grounding like you. But I've just followed the instructions. But I have thought about adding another grounding rod.
I just purchased Will's Mobile Solar book. I like it but the very small font size makes it very difficult to read for my old eyes.
Will, your title indicates this video is about OFF GRID SYSTEMS ONLY yet you continually talk about AC inputs. If you have AC inputs then it is not off grid.
How about another video about true off grid systems with NO AC input at all.
Should there be a neutral to ground bond screw in the sub panel box or no ?
A local grounding to your own earth spike would make sense in case of an outage of commercial power, which would cause you to lose their ground reference. But in such a case, you’d also need to have an Earth-Neutral Bridge (the single point where it’s all bonded), which flips automatically between commercial power ground and your own local ground, depending on if the commercial provider is up or down.
Surge protection on for each fuse box on the PV side is definitely a plus. I use 500V SPD’s.
No... loss of utility input does not interrupt earth grounding at the meter. Only way to interrupt that would be to disconnect the earth conductor feeding the ground rods at the residence ot the pole.
@@SuperVstech Not my experience… I have SMA PV inverters, and every time we had a loss of mains AC, we had a PE (potential earth) fault that caused the inverters to stop making power because they assumed grid failure, even with the micro grid present. An Earth-Neutral bridge bonding that also included a local ground spike fixed this.
@@DJMT-Africa If there wasn't a neutral to earth ground bond at the the main disconnect, then that was your problem, and it would have been in violation of code. Downstream panels/subpanels from that point onward must have their grounds and neutrals separated, unless it falls under some exception.
@@davereichert It could be that code in my country is different than in the U.S.
The NEC requires you to bind neutral and ground on the secondary of a separately derived system (transformers, solid state inverters, etc.). The reason for this is because the primary and secondary are physically separated, therefore the grounding connection does not transfer. You should bind the primary and secondary grounds (exclude the primary neutral because it is bound with the ground upstream).
But what if the Secondary is NOT connected to the onshore grid panel? if you add a ground (no longer free floating) then you may create a ground loop or have a gradient problem even though you may not think they will transfer. 30 sec and 5 min portion of this video.
Bonding Will, everything that is not the earth connection is a bond, not a ground. We use grounded bus bar in large incoming, high voltage vaults, as well as places like server roms to bond equipment to earth.
You are absolutely correct..!! It is clear you either studied your ass off self-taught or took engineering because you're always spot on!
I can see adding a ground rod only if this is for an off grid 120VAC or a 120/240VAC system.
In this case, it would be the only ground rod.
Otherwise, you are correct, 1 ground rod at the service entrance only when connected to a grid-tie system.
But, what if you are using a 120VAC inverter in combination with a relay that redirects the load back to grid when the inverter turns off?
The grid side is grounded, but the inverter side would not be.
I have several of these systems, and I tied all my grounds together on each one.
This grounds the inverter cases and the inverter output.
I love it that you read and understand the manual. That's distressingly rare.
It's amazing to me how many people misunderstand the purpose of earth ground. Mostly people seem to think that earth ground protects them from getting shocked somehow. Lack of "earth" ground doesn't mean you don't have a ground at all, it's just not tied to earth. Your ground wire still acts as an emergency return path to the breaker box to trip the circuit breaker if needed, but that ground wire doesn't need to be tied to earth to perform that duty.
By not having an earth ground you're actually decreasing the chance of being shocked. Since the "earth" you're standing on is no longer a conductor you can no longer get shocked by simply accidentally touching a hot wire because there is no "return path" through the earth for that current to flow through your body.
In fact: a common piece of safety equipment used by crews working in outdoor / wet environments is something called an "isolation transformer". It's a 1:1 transformer (So it doesn't step up or down) that plugs into a wall socket and creates a new electrical connection that creates an "isolated" electrical path that is no longer referenced to ground. This is used as a piece of safety equipment because by removing the earth ground as a return path for the current it makes it safer to use electrical equipment outdoors in wet conditions.
Off grid inverters achieve the same result as an isolation transformer. They effectively "isolate" the electrical system from earth.
You don’t ground your generator if you plug in to a appliance!
You also don’t ground your sub panels
Circuit breakers are overcurrent devices, and will not trip on a ground fault that isn't overcurrent. Please fix your comment.
This isn't worded accurately:
"Your ground wire still acts as an emergency return path to the breaker box to trip the circuit breaker if needed..."
As a counterpoint, not bonding to earth ground your system ground can float significantly above or below earth ground. You will then become a path for that equalization. Usually it's under a hundred volts and very little current BUT it can get crazy in certain situations. This effect is one of the big reasons we all ground to Earth and don't encourage floating ground.
@@FrancisKoczur Circuit breakers aren't designed to trip on "ground faults" at all in any circumstance. In fact a "ground fault" would make a circuit breaker *less likely* to trip because a "ground fault" generally means the return path is compromised in some way.
The purpose of the "ground" wire in a circuit is to provide an "low resistance" emergency return path to the breaker box. The "low resistance" piece is key to this. By providing a low resistance return path if the hot wire were to come loose and touch the metal case of an appliance the low resistance return path would ensure the breaker trips as many amps would instantly flow through that return path.
A "ground fault", by definition, is a condition where this return path is removed or damaged, which would prevent the breaker from tripping and would create a shock hazard if the hot wire in an appliance become loose, frayed, etc.
Circuit breakers do not protect against ground faults unless they are GFCI type circuit breakers. GFCI protects against ground faults, circuit breakers do not.
Either way the situation does not change based on whether your ground is tied to earth or not. The low resistance return path from the appliance to the breaker box is what's important, not whether or not the breaker box ground is also attached to earth.
@@oshavlfarms7239 As a counter counterpoint: Every time someone uses a portable generator, or one installed in an RV or truck, or any kind of mobile/portable inverter such as one installed in any kind of vehicle, they are utilizing a floating ground. Think about how many thousands of people are using one of these floating ground devices every day from long haul truck drivers who aren't allowed to idle their engines and yet no-one seems overly concerned about the danger.
That's because the amount of charge buildup on these smaller scale systems is not very large. Even if there was a significant voltage differential of 100+ volts: it would be the same as touching a tiny capacitor which was charged to that same voltage. The reason why it's not a big danger is because it would result in a microscopic amount of current flow and it's large amounts of current, not voltage, that is dangerous.
With something as massive as the grid that's a real concern, and which is why it's earth grounded. But with a small off grid system it just isn't.
I have a question, is that gray power panel a main panel or a sub panel? As a main I have no problem with it,just it has no main shutdown in it. If it’s a sub panel the grounds and neutral should be separated not bound together. What you are saying is right, one grounding point in the main panel box. But you can have more than one ground from that main box. Hear we have to have at less two a two ground rods or a ground rod and be bounded to the water pipes.
Will, Great point. A similar question relating to those solar generator/power stations. I believe they are not truly grounded. The A/C output runs on floating neutral. What if, when the A/C charge input is connected. Would the power station be grounded during the time through the A/C input cable? Now, would the ground pass through to the A/C output if there were output load plugged in the A/C output jack?
Great presentation and explanation! Keep up the great work and posting videos you're saving equipment and you're definitely saving people for some nasty shocks.
Please provide some visualization on this topic. I have seen an end to end Inverter/Electric Sub-panel/Battery setup video and the gentleman there grounded the whole system with a true grounding electrode. Basically a separate grounding bus bar in the subpanel which is connected to inverters as well as true ground electrode outside.
You are a wealth of knowledge in solar generation systems. However, this video was like another language. I’m sure the more advanced people could follow all you said. Me, not so much. I do understand ground to some degree. I understand how earth ground rods and such work with AC electricity. I was looking for help with the correct way to protect my small 4 panel system. My concerns are lighting protection for the panels. How and if I need to ground the wiring. How to connect my inverter to ground. That sort of thing. I will search your other videos.
Thank you….
You do a very good presentation on all of your videos keep up the good work thanks..👍👍
Really falling off that cliff of the Dunning Kruger effect curve if you know what I mean.
I guess that’s progress…
I appreciate this info. I'm 100%off grid and I was curious if I should have a earth ground connected. I bought a grounding rod but have never hooked it up. I felt like it was a complete closed system and didn't believe I actually needed one.. I have a 5kw eco-worthy hybrid inverter. Connected to my camper breaker box. I also have a inverter generator hooked up to my system to charge/bypass also I have 12 solar panels.. so... Should I use my ground rod?? Thank you
On my steel boat, I have a separate 24V lithium battery just connected to my mpp 3k inverter charger. I run the DC bus floating, with a 1 meg ohm resistor between the minus and the central grounding point. This way, I have the added safety of a floating system, and prevent static charge from building up on my DC bus. All Protective Earth conductors end in a central grounding point connected to the hull, just behind the isolation transformer. Shore power Earth is connected to a parking connection on the isolation transformer. When the boat is on the hard the shore power earth must be connected to the hull to prevent having a large steel structure that is unbonded. Marine Electrics in a Nutshell.
Hello Will, I have just discovered your videos and will be devouring them over the next while. Thank you for posting them!
I have a situation that as a non - electrician has me confused, and I am hoping maybe you might have an answer for me.
I am currently in the California desert in my solar powered cargo trailer/RV conversion. I am an astrophotographer, and spend my winter far out in the desert looking for dark skies. I have 4-325 watt Panasonic solar panels on the roof and 3-300 amp hour Lifeblue batteries for 900 watts total. The charge controller is a Midnight 150, and the charger/inverter is a Magnum 2000. The system was originally installed in my 5th wheel RV about 6 years ago by a very reputable solar company that specialized in RV installations. They have moved on and no longer do installations on RVs, so I can't talk to the people who actually installed it.
I recently moved the solar system from the 5th wheel RV to the current cargo trailer/RV conversion. Grounding to earth in an RV is not practical of course, and nothing on the solar system has been grounded to the frame. I had read that the panel, inverter, and charge controller should all be grounded to the frame, yet they weren't by the original installers. The team that installed my system had installed solar systems in about 3000 other RVs before mine, so I doubt if they just "forgot" to ground the solar components to the frame. I have to think it was intentional. So when I moved the system to the current trailer, I didn't ground anything either. So far all is working great, with 4 120 volt and 4 12 volt circuits. Only the fridge 120 volt circuit is not on a GFCI. My 120 volt Samsung home fridge specifically says not to put it on a GFCI protected circuit.
So my question is probably obvious: Should I be grounding anything to the frame of the RV? I used all metal outlet boxes, and they are all on internal walls. The outlet, and the box itself are grounded with a pigtail to the ground wire that goes back to the panel.
As a non - electrician, I have a hard time understanding why I would ever want to send electricity into the metal frame of an RV. This seems crazy to me, and a recipe for a serious shock. It seems like I now have a closed electrical loop with the panel. Why would I want to send electricity to the frame of the RV, under any circumstances?
As an aside, when I was a kid I stepped off a poorly grounded RV just after the rain had stopped. The step was metal, and I was barefoot and wet. I can only remember screaming and being frozen in place for a second or two before passing out and fortunately falling away from the step and breaking the ground. For a few hours I couldn't walk, and both my ankles were really sore. Within a few more hours I was fine. I suspect it would have killed me in a few more seconds if I had not passed out and broken the connection. It was a really terrible experience, and I don't want to relive it because I made a grounding error. But intentionally sending electricity into the RV frame just seems like the last thing I would want to do. Isn't an electrified RV frame what shocked me in the first place? Any advice much appreciated!
I'm in a small cabin and also wondering this.
what about the panels? should they be grounded and bonded to each other? ( the framing)
Just installed an axpert max 7.2kw, and as soon as it switches some internal relays while powering on, the house goes dark. Had to remove the input ground wire for it to run. Im assuming the inverter switches the neutral to ground internally 🤷♂️
In the manual it states the pv array must not be grounded to it as well..
Seems a bit over complicated ... my understanding of what I think I heard ... a panelboard/breaker box (out of your inverter) should always be tied to an earth ground. You may choose to earth ground the metal case of your outdoor solar panels for lightning protection. However, do not earth ground your solar panel output/PV supply to your charge controller. It's okay to surge protect the PV supply, but again, do not earth ground it. Is that accurate?
Dude ur channel Came on my recommendation, glad i found...ur videos are awsome and well explained..
Its code to bond all electrical equipment including what you have there. Yes you should have only 1 point of ground but everything is required to be bonded.
I would need a diagram to be sure though maybe he has it done right.
@@networkingdude For me , as a retired HVAC guy . All this is getting a little more confusing . After watching the video Will provided a link for , actually destroys almost all that we learned about the " reason " for a " earth ground " , and WHY . We were told that the " bare ground " for equipment was to make a short to ground on the equipment , safer for anyone who might touch it otherwise ?! We were never told about anything about two " earth grounds " creating a loop , and back feeding " if you will " and destroying other equipment ?! I still question though , that if those rods are far enough apart , that would happen ? I am actually still confused about " where " in that system , Will has a earth ground ? Does the load ( A/C unit ) have a earth ground ? Plus , a lot of that video refutes what I was told by a Master , who was in our shop . Though , all that was Pre 99 . I did my HVAC classes mostly tween 78 - 88. Glad I am retired now :D
@@indycharlie He stated that he was going to be adding utility input to the inverters, and that will be grounded to the service entrance. That is the earth ground for the inverters and therefor the system. He hasn’t installed that yet which is why it may be hard to visualize with what he is saying. Also, you need earth ground when dealing with utility service because that’s how the grid is grounded. In an isolated system it only needs its own ground. Think of it like a car, which is its own isolated electrical system. There is no earth ground, but everything is “grounded” through the negative terminal. An off-grid system is similar in this case.
@@coryvincent6249 First off . I am about to turn 71 , and have been retired since 06 . When I retired I was the " work leader " in a HVAC Shop on a AFB . I had 22 guys coming to me daily about trouble shooting , and other issues . We also did Controls . Electromagnetic , pneumatic , and finally DDC. My days were filled with answering questions , attending meetings on remodeling of Bldgs , New buildings , and studying NEW equipment manuals & data . I am not trying to scarf myself here . But when I retired after 31 yrs . I said I would never read another Tech Manual , ever again . So , between my age , and WANTING to forget it all . Including what I knew about the NEC . My thoughts may be wrong . But , I still see no way that on this " isolated " system , as he installed it . That there is a place anywhere to a " earth ground " . Are you saying he is bringing in a " Public Utility " into the inverters ?! So , is he putting in a manual disconnect for that public utility ?!? Part of this " might " be the Language used at all the AF schools I attended at Sheppard AFB ?! DOD was a weird animal , in this regard . Yes , I understand a 12 V DC car . But he is using 120 / 240 VAC single phase . And from what I was taught , and remember . That " isolated system " would need a " earth ground " that is for ( as we were taught ) a safety , so a short would take that path , and NOT use you . But hey , I never installed a system that was " isolated " from the Public Utility , at any of the AFB's I worked at . Thanks for the reply to this old , tired , X VN combat medic . Have a good one . PLEASE DON'T LET MY CONFUSION , CONFUSE ANYONE ELSE , READING WHAT I HAVE SAID .. LISTEN TO "" WILL "" .... . ..... Gubs
@John R what you have is fine, as long as you don't bond the neutral at any other place (including the inverter).
I agree completely, but I heard rumors for questionable sources that a Tesla charger might be very finicky in this type of circut. I was hoping to see how that worked out today. Great tutorial thanks.
More explanation on the ac input please, as this is off grid, are we assuming the ac input is a generator with its own true earth (rod) and does it have a men link?
May sound stupid but someone could ground this system using a low resistance power resistor as a shunt system, so as to not cause the inverter a complete short circuit and blow mosfets but make it possible to have a return ground path in case a short happens in the device or local code demands you ground the system. The other option is a seperate ground with no bonded neutral just to dissipate static buildup.
My growatt inverter specifically addresses this in the manual where I have to have an inverter controlled relay to bond and unbound my ground to neutral on the inverter output specifically when it switches back to grid power.
Perhaps you can do a video on this?
I have loads that will not run if the neutral isn't bonded to ground
Ohh is this when it is being used as a UPS? I usually disable that in my systems.
I suppose, that this relay acts as "automatic grounding relay" for the following reason. Inverter itself can be considered as independent AC source, like gasoline/diesel generator. So, if this inverter is in Off-grid mode (island mode) without any connection to AC grid, then, its output neutral must be grounded.
If inverter has AC grid connection, AND its neutral runs from AC input to AC output continuously, without any interruptions like contacts of relays, then, neutral grounding of AC output is accomplished by AC grid's already grounded neutral. Following yours descriprion of Growatt behavior and need for specially controlled relay, I think, that neutral from inverter's AC input to AC output can be breaked by some internal relays in island mode. So, this relay is needed to groung output neutral locally, near the inverter itself. The same requirements for output neutral grounding are exists in the world of Telecom inverter systems (DC 48 V to various AC voltages). We also need to ground AC output neutral in case of absence AC input connection to AC grid.
@@WillProwse I run solar as my primary and the grid as my backup. The grid neutral and ground are bonded in the main panel. So when I'm running in grid mode all loads function normally. When the batteries charge up and it switches back to the inverter my loads stop functioning because the neutral and ground output of the inverter are not bonded. By code I can only have 1 neutral to ground bond in the system. If I connect neutral to ground on the inverter output without a relay I end up with 2 bonds when it switches back to the grid.
The growatt has normally open and normally closed wire connections for this exact purpose to control a bonding relay.
Yep, @john, it's a requirement in my country, when the inverter operate on battery, neutral must be connected to ground. Mppsolar inverter don't do that. Shutdown ac input and check the voltage between neutral and ground. Should be zero, but its not on mppsolar inverter. You can find a grounding box, wich is simply a relay that connect neutral to ground under a condition controls by the inverter optional relay output. Need a special firmware version to activate the relay when ac input is not present. Otherwise you can implement the same thing with voltage detection on ac input and some relay. The thing is mppsolar is totally speechless about grounding to neutral regarding regulation and theirs products.
Hey Will, can you do a video where you show everything and anything you need to do a off-grid solar charging setup for an electric car to charge at full level 2 charging? I can charge my Nissan leaf at 6.6kw with my grid tied chargepoint charger. The charger is plugged into a 50 Amp, 240 Volt Nema 6-50 outlet. Thanks and sorry if there is already a diy video for this. I would like to put solar on my garage and then have the entire garage be off-grid also.
This now raises my own questions. Is it possible I can send you a YT link to a video of my setup with my current ground configuration, get your feed back?
Hi Will, I have a cuestion? I install a inverter powmr is 230, 24v 3000W off grid when I check the power in the output lines, one give me 90v and the other line 170. I conect the ground I install a ground route outside the storage.
Very interesting stuff about the "ground loop". And I have a question. My house has a ground for the sockets (with those metal rods in the ground at the corner of the house) and a separate ground (another metal bar at the opposite corner of the house, as it happens...) for the tv cable. Is that wrong? I am assuming the shield on the antenna plug at the tv is connected to the power ground. Maybe not. Am I in danger? Thanks!
Electrical codes should require all the grounding rods to be "bonded" together (i.e., there should be a direct ground wire connection between all grounding rods, which should also be no further than 16 feet apart).
You mention the bus bars are on opposite sides of the house, but that's probably fine as long as they share the same grounding rod or the grounding rods are properly bonded. If you want some piece of mind, you could trace the connection leaving the TV cable bus bar and check that it connects back to the service ground.
Grounds need to be bonded at the rods. Delicate electronics are not where bonding should occur. If the potential of your antenna ground is better than your ac ground, your entire/most of home grounding system will attempt to pass through your tv. By bonding the rods, both should have nearly equal potential and surge/emf (why you need a coax ground) will go to shortest path vs path of least resistance.
What a great community! Thank you all for trying to help me understand this better.
The antenna ground is something I did myself to get rid of EMF interference and I can tell you that is NOT connected to the mains ground. But I do wonder if TVs will connect the mains ground to the antenna ground (shield).
I need to do some better research on this. Also, this is in Europe, on a 240V connection. Some things (codes) might differ.
One more detail: the cable tv on my house (which goes to multiple tv sets) is NOT coming from outside the house. There is a fiber coming in with both internet and digital tv signal and it goes to this box that outputs internet and cable tv...
You should use wiring diagrams when discussing this subject
I've never been more confused about grounding and bonding after stopping here.
One thing I haven't seen in any solar vids on youtube is do you ground to your chassis in a pickup truck caps house battery solar setup with inverter that's not tied into the start battery
I'm not sure how you run ground in the states, but the ground we use if for fault current return and has nothing to due with lightning strikes, that's what lightning arrestors are for. In most cases using the M.E.N. system (multiple earth neutral), the main earth is tied into the neutral conductor. Any metallic enclosure has to be earthed so that if a fault occurs with an active conductor to frame it will trip the circuit breaker, and any fault that occurs through a person to ground trips the R.C.D. (residual current device). However having said that we also have other earthing systems other than M.E.N. such as the Direct Earthing System, The E.L.C.B. System (Earth Leakage Circuit Breaker) (voltage operated type), and the S.W.E.R. (Single Wire Earth Return) that uses only one wire and the ground is the neutral return system. I found what you were trying to say a little confusing but that may be attributed to different terminology used. But basically yes, the earthing conductor is used for return fault currents and has nothing to do with lightning. Our supply authorities use a three phase system for reticulation and distribution, generally delta to star step down transformers where the centre point of the star connection is the neutral connection which can also be earthed. Nice watching albeit a little confusing.
What about a solar set up in a vehicle how do you protect against lately and does the system need grounded?
Great video, but I had a question about these inverters. I went on their website and found that these are “off grid” inverters. What is this “AC input” that you refer to in your video? Is that for AC charging?
They have many types of inverters, I think the ones Will has are "hybrid". You have 120V in from the grid yes. That can be used to carry loads or charge batteries when the solar array isn't producing. You can choose what power to use for the load side of the inverter... give priority to the solar and batteries or the grid etc... depends what your goal is. Lots of people just use these things as a type of online UPS for critical circuits and the batteries are just there if the grid fails. One of the inverters cuts out the need for transfer switches and is flexible on where it gets energy ... arrays, generators, the grid - everything but rubbing two sticks together. I've powered/charged mine with a step up transformer using the dual alternators in my truck (36V @50amps step up)
Depends on what type you buy. I have these hybrid off grid inverters and I can use it completely off grid with a generator as a back up or connect it to the grid if the battery bank is depleted and no sun.
I do have my panels on their own grounding for the panel frames and dc lines are fused incase something tries to send more amps through the dc input lines like a failed shorting inverter that backfeds ac to the panel frames.
Hey Will. Very informative videos! I’ve watched many of your videos on lithium batteries but I wondered if you have reviewed later generation lead acid batteries called crystal lead batteries? Not as good as LiFePO4 but reportedly much improved on flooded lead acid batteries. Could they be a low budget option worth considering?
I swear you’re reading my search history. I was just looking up how to ground these systems
You can have multiple ground rods as long as they are all connected with heavy wire (6 AWG) or copper strap. That will eliminate any voltage potential between the separate circuits they are connected to. Eight ft. rods should be spaced 16 ft. apart.
You need to get a NEC code book! A supplemental ground rod is only required when the 1st measures over 25 ohms. Then a 2nd one 6ft from the 1st. An inspector will never question if he see's two ground rods spaced 6ft apart.
The larger the connector cable to the source from the output board, the smaller the earth fault loop impedance, making it trigger faster under fault conditions. You are correct, you wouldn't want to connect to a house earth system, some (most) do not have sufficient equipotential bonding and this allows for transient currents on the earth conductor, and we are not just talking milliamps.
Thanks Will. Not many people talk about grounding system for the solar system and I’m glad you did. I plan to install a Growatt SPF 5000ES hybrid off grid solar inverter in my RV Bus in Bangkok, with Lifepo4 battery bank, and solar panels. This inverter will take solar power or take AC shore power to charge batteries and convert battery DC to 220Vac output to power Dometic Aircon and TV, etc. So here, I have input ground terminal when I take 220Vac shore power. My question is do I need to connect output ground for the AC output or should I leave it unconnected (open) ? If it is needed, where would this AC ground connected to in the vehicle ?Hope you could help explain.
I see you have two DC fuse blocks but you don't talk about if they are fast or slow blow. and if you are going to use a fast blow fuse it could help mitigate the need for a true ground.
another reason you could want a true ground is power feedback from your AC or 220v/240v power tools that don't just turn on/off clean.
Personal Opinion, obviously the argument for/against grounding on these internal components is open for discussion, but I believe there is something to be said for earth grounding exterior things like panels and heat-pumps/condenser units. These are what can/will build up a potential (static charge) and so will increase the likelihood of a lightning strike. Once a strike occurs, IMO no realistic amount of grounding will really protect that equipment.
What a about grounding for my inverter power in my RV?
Should I ground the case to the negative (chassis) on my DC system?
Lightning protection is best done via lightning rods, which have their own dedicated earthing conductors not to be shared with anything,
as the lightning will travel down it, which then yes produces a gradient voltage across anything it touches, including dirt.
The house grid earth connection is there in case the earth connection at the pole transformer is lost,
the connection to earth is maintained, via the bonded neutral (both at the pole transformer and the house mains panel).
The neutral-to-ground "bond" is there for fault current to travel back up the neutral to the power source,
tripping the circuit breaker on the hot controlled conductor.
This conductor is the ground pin on a wallsocket, it also neutralizes the live voltage during a fault so that humans don't get shocked.
Some SPD's just happen to use one or both to achieve surge dissipation, which is fine.
The neutral should only ever conduct the operational current, which is also flows back to the power source tripping the breaker during normal operation. It may or may not also conduct fault current by happenstance.
There should only be one earth connection point and the ground should never be used to carry any operational current, this also prevents voltage gradients from damaging equipment.
If you have properly installed lightning rods there shouldn't be a need for array SPD's, other than perhaps static discharge. A direct hit will render just about anything dead regardless of how good the SPD is designed or believed to be.
Some inverters are single phase, some are split-phase, some have bonded neutral and some don't, all of which adds extra complexity for DIY'ers. If anyone is unsure then they should just contact a certified electrician to do the work, it might save their life and/or not burn their whole city to the ground. (and code compliance and all.)
William you are so informed thank you
I was wondering what the best way to ground the eg4 hybrid minisplit would be. Should the panels be earth grounded separately?
If you wanted to add a 240v shock prevention device, look into adding a residual voltage device (RVD)
Excellent video, Will. A question: Let's assume you were NOT connected to an AC input with an earth-connected ground and were truly grid independent. Would you then connect your breaker panel to a true earth ground? I assume so. The reason I ask is that some people might have a system whereby they are *sometimes* connected to an AC input with earth-connected ground (tiny house on wheels connected to extension cord) but sometimes they are off grid with no AC input. Would you have to disconnect and reconnect an earth ground to this breaker panel depending on if AC input is available?
There is the argument that on some devices, static accumulation can cause a shock if not connected to true earth. I have never experienced it before. Having a floating system, not connected to earth at all, is not necessarily dangerous. I'm still trying to find devices that can accumulate charge as I've read from multiple sources. I test for potential in the cases of my equipment and have never found it. Besides that, I don't see any issue having a floating system.
@@WillProwse RCDs, RVDs?
We have a old lead acid off grid system. Way before all this new stuff. Just had a lightning bolt fry our inverter last night. Guess it's time to switch over!
I have read many comments and happy to see so much interest and concern over safety and desire to become more educated on it. Please do so!
One of the issues, imo, is our words.... take ground, neutral and line. We all use ground" wrong at times. Many times I say ground when I mean desired return current path, which in houses is called the neutral.... which is (typically) strapped at the box to earth ground.
And speaking of ground loops with myself and other saying how they are bad... when the electric company safely has created ground loops with your neighbor's earth ground rod.... all depends on where the loops are.
I'm happy to see these discussions : )
Use Good sense... Common sense? def common these days... might not be the best! An example of a play with words intentionally when the understanding of "common sense" to make good decisions is not properly conveyed. Same as more recent technical words like ground etc...
Will does good with follow up and education, ya'll do the same now, ya hear?
It's a year later, but here is how adding additional electrodes (ground rods) works. You can add as many as you want, anywhere, but they must be bonded underground (i.e. 2/0 copper or bigger), and you can space them up to 10 ft apart. The OP is talking about adding a standalone ground rod that is not tied together underground and is most likely more than 10 feet away. That isn't good.
I wonder what qualifies as a large pv array? I have 13kw array and not sure if I need an SPD to an earth ground (8' copper electrode I reckon). This system is off grid if that makes a difference
Do you need grounding? You seem quite balanced to me...
The panel needs to be tied to an earth ground and technically according to National Electrical Code, you should NOT bond Neutral and Ground in a sub panel. Neutral and Ground SHOULD be bonded in your primary panel ONLY , as you want to earth ground and Neutral bonded in only one place as you are saying. In this system, I don't think there is a primary street power feed, it seems to be only powered by the batteries. So in this case if I am correct about the AC inputs not being present, it is a gray area sort of... The only other thing I see is the use of temporary wiring meant for extension cords. The NEC requires Romex, or equivalent vinyl jacketed wire designed for permanent installations in homes vs the rubber jackets used in temporary (extension cord) wire which is what I think you have used here. When you add the AC inputs, I would recommend running the two conductor with ground (Black/White/ground), with the ground wire going to the earth ground in your feeder panel (assuming it is your primary panel and not a sub-panel) and bonding it to the earth ground input on the inverters and the panel. Or you could run a single ground from your main earth ground in your main panel right to the earth ground on the inverter distribution panel. Then un-bond the neutral and earth in the inverter panel so everything is connected to your one earth ground on your main panel., they looked like they were bonded in there but can't tell for sure. The earth ground is primarily for all of the stuff you will be running AC from the panel, but my inverter has an earth ground connection and I would think the MPP does as well. As a safety concern, many items are designed not turn on if there is no earth ground present, such as tesla charging for instance.
NEC doesn't well adapted to presence of additional independent power supplies at household: it was written with only a grid connection in mind. So, grounding on inverter's neutral will strongly depend from individual system's scheme. If inverter(-s) system is completely independent from AC grid, like Will's system from this video, then neutral must be grounded right after the inverter, in first distribution panel. Or, which preferable, it must be grounded at inverter's output terminals. In case of several inverter units in parallel/split phase configuration - it is better to create a neutral busbar for collection (combining) neutrals from all inverters. This busbar will be the point of neutral grounding. This busbar must be installed close to inverters.
My plan was to ground solar panels and use ac in on inverter as the inverter wireing ground? Let me know should i run the ground from solar as well?
So, I have my 110v from the service panel on the pole to my inverter then off to the RV. The solar panels are mounted on top of a metal utility trailer. The panels are all connected with ground clamps and wire. WHERE do I put the ground wire from the panels? The panel at the pole is earth grounded. Thank you
You are conflating neutral bonding with grounding. The neutral is bonded to ground at ONE point only. Ground does not carry ANY current when done properly and there is no limit to it's attachment to earth. For example, all metal within 5' of water is required to be electrically bonded to earth, a/k/a ground. This includes rebar, plumbing, metal framing, windows, doors, screen enclosures, etc. Some of these items, such as copper pipe and rebar, may be buried in the earth and serve as a ground path. Again, there is no limit to points of contact with earth for bonding and more is better, but all of them MUST be tied together. This is all covered in the NEC manual which you are required to comply with.