Piggyback Fuse Holders SAFE OR NOT? A Piggyback bench test - by VOGMAN
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- Опубліковано 1 жов 2024
- Piggyback Fuse Holders bench / safety test : I’m looking at the Piggyback Fuse Holder to determine if it’s safe to use. Can they be fitted the wrong way? Can they blow existing fuses? Do they draw an imbalance of current from original fuses? Must they never exceed a certain rating? These and other questions will be answered here as I perform a series of bench tests on this electrical component to test its suitability for safe vehicle use.
Piggyback Fuse Holders are commonly used in vehicles to add a circuit within the fusebox. But are they safe? People question if they are reliable or even dangerous. Probably the most commonly asked question is, can they be fitted the wrong way - and if so, what happens?
I've already added an instructional video to UA-cam showing people how they can safely add a fused circuit to their vehicle using a piggyback fuse holder which you can see here - • How to add a fused cir...
But people still have concerns and questions and these I have tried my best to answer in this video.
SAFETY CONCERN - CIRCUIT OVERLOAD...
The purpose of this video is purely to test the functionality of the Piggyback and its suitability for purpose. One thing I don't cover well in this video is the safety concern that faces every electrical extension scenario and that's overloading. Just because you CAN add more outlets, whether domestically or in a vehicle, it doesn't follow that you should. It's possible to overload the original wiring, regardless of fuses. This can result in electrical fires...
Please see my video dedicated to the subject - here • Piggyback Fuse Holder ...
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As others have said great video but one additional thing: if the piggy back is the wrong way round then the original fuse will see the amps from both circuits potentially overloading the original circuit. The tests here won't show this as they tested the circuit amps past the point of the fuses. If you remove the original fuse and test the amps at that point (I.e amp meter bridging the original fuse) you would see double the load with it the wrong way round.
This matters in the sense that you could blow the original fuse when the original circuit is actually fine and should be operating. You could also create a load that would always blow the original fuse in this set up (I.e original fuse at 20a with 10a load, new fuse at 20a with 11a load both circuits working as desired, the original fuse will blow every time both circuits are required)
Excellent demo - thank you very much for taking time to illustrate this in a very clear step by step logical and sequential manner. Brilliant!
I feel very reassured - I'm planning on permanently wiring a dash-cam to my car, no huge currents being drawn and this just clarified something I wanted to know about piggyback fuses
Many thanks : )
Using it the 'correct' way routes the current to each device through a separate fuse. Using it the 'wrong' way routes both circuits through the original fuse and the new circuit through the new fuse. This has two fuses on the new circuit, (which are not needed) and the current from both circuits passing through, and possibly overloading the original fuse. If that blows, both circuits are out and you've now got two circuits to troubleshoot. I agree, on low loads, either way works fine. But if you increase the current you ultimately have both circuits on one fuse.
I can only speak as I find, Bill. The tests I conducted on just one (non-branded) PiggyBack showed no evidence of sharing current when the device was inserted the wrong way. It's possible that other makes could behave differently I suppose but the one I showed here safely fused both circuits, regardless of how it was inserted... though obviously there is still a right and wrong way : )
I agree with you completely about overall load... I don't think these things should drive anything heavy duty. A dedicated separate fused line would always be the way to go if needs were more substantial.
Thanks for your input.
Bill Vernieu is correct. With both fuse in place in the piggy and correctly connected and oriented the connection is parallel for both fuses, i.e. each fuse protects each circuit. Now with the piggy connected wrong way around, with both fuses in place, the original fuse works as the fuse for both the circuits. The red circuit fuse is defunct. That is why if you remove the green fuse at this point, the red circuit fail to light. So how is this possible? Simple. The original fuse has both legs connected to the circuit but the piggy's red fuse has only one leg connected to the circuit. One of the legs is defunct in the red fuse. That is why by turning it around (without the green fuse in place) it does not carry current,and therefore no light. Try drawing the piggy's internal connections and leave out the piggy's one leg (the one nearest to the red wire for tapping current). This will be your aha moment!
One of the easiest way to test this hypothesis is by showing the lack of continuity between one of the legs of Piggys red fuse (nearest to the red tap wire) and the the corresponding side leg of the piggy itself. Use a multimeter to check for continuity and insert one lead into where the piggys red fuse leg would go into the piggy itself and the other lead of the multimeter on the corresponding side of the piggy. At one corresponding side you have continuity and at the other corresponding side there is no continuity.
Best explanation of a add-a-fuse I’ve seen, great job1
Many thanks : )
@VegOilGuy Automotive tech here. You've proved yourself that the current would all go through the original fuse if the 'piggy back' is fitted the wrong way around in the video. If only the 'piggy' fuse is fitted, it only works one way around. If both fuses are fitted then it doesn't matter which way around you put the piggy. Therefore one way round, (The fuse positive input closest to the piggy output wire) then all the current has to run through the original fuse first for both circuits to be live, the piggy fuse then gets it's input after the current has gone through the first fuse.
Hi Josh... I might be misunderstanding you or you might be misunderstanding me, so to clarify my conclusions were this:
1) It can be inserted the wrong way round but this only results in an inconvenience IF the original fuse is blown or missing
2) The loads AFTER the fuses are NOT shared. The fuses always act independently
3) The load BEFORE the fuses draws more currently - obviously as we're adding a second device
4) If fitted the correct way round and both fuses do NOT exceed the current rating of the feed wire itself, then everything should be safe to use.
Hope this helps : )
Geoff
Good video Geoff but you should really mention a safety issue with overloading the supply wire!
I have been investigating these piggy back circuits and whilst I am sure they are fine adding low current circuits, there is a massive implication adding high current circuits. How do we know the wire supplying the original fuse can take the circuits combined current and won't melt and worst case catch fire?
I think you should really make this clear - I finished watching the video with a clear message there were zero safety implications!
How about adding an extra test to your video. Pretend your supply wire is only spec'ed to take the original fused current by using a fuse on the supply wire of the same value. When you double the current with the addition of a piggy back circuit the wire 'fuse' will melt - this could be your loom wire melting!?
For me this is the biggest concern rather than which way round the piggy back fuses are inserted. A novice (like myself) might blindly use this and overload a supply wire with all sorts of consequences!
+Nick Luc Cockman
Hi Nick. That is a fair point well made.
I did think that I had made mention of overloading the circuit and even suggested that personally I wouldn't recommend anything that would exceed 10 Amps. But if you haven't spotted this, either I never actually did it (and imagined the whole thing - nothing new for me there) or I didn't do a clear enough job.
Thanks again Nick. I'll have to revisit this later when I have a spare few minutes and see if there's a better way of getting this important safety tip across.
Best wishes,
Geoff
only thing i can think of is overpowering the power wire into the fuses. just random numbers here but say the wire was rated for 12A and you had a 10A circuit. that's fine, no issues. but if you piggyback it so there are now 2 10A circuits, that's 20A which exceeds the 12A wire rating. not sure if that is how it works, i could be wrong, probably am. but then again with both circuits you were drawing less amps so...hang on, back to the drawing board for me....
badbradmx, a 12 gauge wire is rated for 20 amps
So if I’m correct, the new fuse goes into the top and the existing fuse goes on the bottom? I just want to be confident I won’t mess up my headlights or other important operations while trying to hook up my police scanner...
correct
It doesn’t matter if you put your piggyback in the correct way
His conclusions at 1:08 : Piggyback fuses are safe and do not overload the original circuit.
YA, Volume needs to be MUCH louder. But Great video. I think the reason the piggy back fuse holder only works when inserted correctly is because the original fuse "BLADE" completes the connection for the positive to go to the add on circuit. Without the primary fuse the power doesnt go to the add on circuit fuse through the BLADE of the original fuse. .
Can you raise your mic?
Fantastic Video!Watched this as was unsure about polarity issues highlighted in other comments. So duly digested your tests and figured I could work out the 'right' way round by inserting the 'piggy back' without the lower original fuse. If it's the wrong way round the accessory won't work. Same as blown fuse?
So did that and one way it worked, the other way it didn't. Sorted thank you.This was for a hardwire install of a dash-cam, I used an empty fuse slot on a 10A heated seat circuit. The vehicle doesn't have heated seats :)
Gonna hardwire my Sat-Nav next and then install some extra 12v Sockets.
It is confusing I know. I sit and watch the video myself sometimes just to refresh my memory, but those were the results I got ; )
I'm really glad it's help you out. That's why I make these videos, so thanks for letting me know.
Thanks for showing the in and out flow on the piggy. People were saying that the current runs in an “x” pattern from the original fuse to the added fuse. You show how both fuses have the in and out sides on the same side like a copy next to each other. Awesome 👏
If you put in the piggy bank the wrong way around an have both fuses in, I believe that both circuits would actually go through the original fuse so that could blow up if the total current of both the circuits is higher than the rating of the original circuit.
Thanks for the comment Alexandru. I don't think so.
The purpose of these tests was to discover what happens when these devices are fitted correctly and incorrectly. I couldn't find any evidence of "sharing" a fuse so I believe if used correctly they're perfectly safe.
Hope this helps.
Best wishes,
Geoff
Actually you are wrong, when the piggy bank is put in the wrong way, the current of both circuits is flowing through the original fuse. You have been measuring current at wrong points, that's why you didn't see it in your tests. Just think about it - if the current of added circuit isn't flowing through original fuse, then it should work when you take the original fuse out. That's what happens only when the piggy bank is inserted correctly. If you're still not convinced, try drawing out schematic of your circuit, it should be clearer.
Could you do another video testing them? I think it would be a good idea to see if plugging it in the wrong way will still protect the ciruits
Thanks for your suggestion. I'm always keen to get requests. But in truth there's really no need this time. If you think about it...
Is the current flowing through the fuse? YES. (this was tested - with a fuse the light lit, without it nothing).
If current is flowing through the fuse then the following circuits MUST be protected.
Get the idea? The fuse IS the safety... its designed to break if too much current flows through it. So a working fuse is a good thing.
Hope this help : )
I think it shares half the original fuse. That is the supply flows across one blade of the original fuse to reach the supply side of the piggy backed fuse. Test it with a blown original fuse installed or a spade connector on the supply side. The piggy should work either way around.
This seems pretty obvious, the power line in splits in two to feed the green line out and the red piggy out, when you put it in the other way, you are only using the green line out as an in and not feeding the piggy line.
VOLUME UP next time you publish your UA-cam video.
Brilliant video! I was going insane reading the forums.
Glad I could help ; )
Thanks. I've been worried about using one of these for a while and this put me at ease. There are so many conflicting opinions on this matter. Appreciate it.
Do both the fuses have to be rated at a different number? For example your green fuse is 30 and your red fuse is 10. Can they both be 30?
As per usual perfectly clear diagrams & so easy to understand even for mere amatuers like myself!! Excellent spoken dialogue , not too fast & good quality "English" that most people who speak it will be able to understand with sheer consummate ease!! Easy sounding dialogue on your ears & this guy so obviously sets the standard for these high class instructional videos!! I've watched hundreds of general interest videos & some of them were absolute sheer rubbish but this guy is well & truly sitting on the top already!! He further goes to prove the point beyond any doubt about background music!! Ya don't need it & especially if you are trying hard to concentrate on something technically heavy!! If I want to listen to music I can merely access my selection of probably thousands of pieces so I don't need my instructional videos loaded with more music & worse, quite often with sheer & utter rubbish crap music. So well done indeed & I can't even suggest an area that requires further improvement!!
Wow, Braydon, thank you. Those are very kind words 😁
Oh I see. So instead of the fuses being parallel, if the piggy back is reverse the fuse become in series.
It isn't in parallel(nor series) or the top fuse would work even when backwards. From what I gather the two fuses are independent as the top fuse is set into a positive line and doesn't connect to one of the prongs coming out of the piggyback. The red wire is the only thing connected to the closes slot in the upper fuse holder. This would explain why it only works on one position when there is no bottom fuse(correct) but it will work with both fuses(incorrect) in the opposite position. It is a good way to test the right orientation as you want it to work even with the bottom fuse pulled to ensure you are running power through the upper fuse and not through the bottom to power the top fuse.
Great video. Much appreciated !!
Thanks a lot. Greetings from Holland.
Thanks Peter. That's very kind of you.
You might want to look at my Fuse It video too - ua-cam.com/video/8omZ545Cw1U/v-deo.html. It talks about using a Piggyback.
Best wishes
Geoff
I agree with your findings, that the piggyback fuse holder is a safe tool (and far preferred to some hacky wire stuffing nonsense).
My only addition to you analysis is regarding the fitting of the holder backwards. As you noted the new circuit requires the original fuse to be installed, and intact, to function. This would be evident if the piggyback were disassembled and the bus bars could be seen, one stab connects to both fuse receptacle and the the other stab only connects to the original fuse receptacle.
Notably, installing the piggyback the wrong way around will cause the original fuse to carry the current for the original circuit (suitable, by OEM design) AND the current of the added circuit. If the added circuit is a large load this could blow the original fuse and lead to confusion as it will be counter-intuitive.
Having said this, sometimes space considerations in the fuse box force us to use the piggyback backwards. As long as we know the limitations and account for that in our DIY designs (and we don't "fix" it by up-rating the original fuse) there should be no problems.
*Thanks for your video. It was very helpful. To clarify, if I am tapping into a 15A circuit on the fuse box, can I use a 10A fuse on the Piggyback fuse holder?*
*To expand on my question, If I have two 10A fuses, is it safe to tap it into a 10A circuit in the fuse box? or should I tap it to something with more power like 15A or 20A?*
Thanks for your question. It's always tricky to answer these sort of questions as vehicles, makes, models, etc, do vary. I can only take a guess and I could be wrong...
So with that said, whenever possible use an empty slot. That's ideal.
Up to 10 Amps, I'd probably chance it..
Which fuse? The chances are the wiring loom is made up of the same size cable to maximise buying power. What I mean by that is why buy thin cable to just handle light circuits when medium thickness cables can be bought more cheaply in bulk and will do the same job? So by that logic I'd probably go with the smaller fuses.
In an ideal world try to look for something that gets used rarely, like electric seat adjustment, etc.
I hope this helps.
Best wishes,
Geoff
They are safe when used right, That is the problem. It is just like using power strips in your home. They get miss used and you have problems. I can plug 300 cell phone chargers at 5 watts each into one 15 amp outlet and not over load it. But one hair dryer will push same outlet to its limit. Those piggy back fuse holders are safe when use right and with some common sense. If used wrong you can have real problems. If in doubt then do not use them.
Perfectly said David. Spot on.
So using 2 fuses slightly reduces the amps (by 0.4 amps)?
Can you cascade 10x wire taps with 10A or bigger fuses? Then you could draw 100A or more. No? Why?
When people say wire taps are safe, they cannot also tell you the wire gauge of the cable they are drawing power from. They ignore the wire they cannot see, that goes from the engine bay fuse box to the interior fuse box. Any time wire size is reduced, a fuse is needed. And a wire tap does not get free energy from somewhere. It is not a relay.
Still don't believe? You might be thinking about only one of the fuse terminals. One terminal leads to the original factory accessory. This one is "separate" with a fuse tap. But the other terminal is the one that is being overloaded, because the 2 fuses ultimately draw power from a terminal that was designed for a specific maximum fuse value. There are many wires leading from the battery or engine bay fuse box to the interior fuse box. And what is their ampacity? Then how can you know if it's safe?
If you've made it this far without believing, you are encouraged to cascade many fuse taps and run many accessories from a single circuit. After all, won't the fuses just blow if too much power is drawn? Well, you might find your fusible links are the only real protection here, if you even have them. Just keep an extinguisher nearby
My question would be why not use the same amperage fuse if the original amperage is green. Going to hook up some LED lights to my 12-volt rear power source and I'm going to use the same amperage fuse that is in that spot fused tap will there be a problem??
Excellant explanation. But missed one detail, that It doesnt mater if we fit piggyback incorrectly, circuit will still work, because whatever we are doing, is on postive side and ground side is untouched. So we are not switching polarities, meaning we are not changing source of positive with naegative, so its safe to do so.
Excellent investigatory skills.. thank you for meticulously breaking this all the way down and for building the little circuit for visuals! Awesome video😊👍🏻💯❤
Glad you enjoyed it!
Could you crimp 2 positive feeds into on piggy back cable? As long as the fuse rating was correct?
At least now nobody can accuse you of not being thorough; you really go that extra mile, which I admire. Thank you for teaching me something new.
I'm pleased I could help : )
I know this is old, but thank you! I have been watching video after video and couldn't understand this until yours
Great videos, very informative. Question I have,
I have to orientate my piggyback the wrong way in order for them to fit back in my fuse box with lid back on ( it’s a Volvo fuse box under seat) I have 2 fuse slits which I identified switched and live and they are unused slots. I need to power dashcam and power magic pro but what fuse should I put in the bottom of the piggyback when I insert wrong way? On top I’m using a 5A on bottom a 5A too? One of the unused slots in the car manual has 5A and the other unused slot is 20A but I don’t have these accessories fitted in the car, can u help 🙏
hi thanks for the videos geoff, however i think you need to make it clear that installing the fuse holder the wrong way around can create problems. installed incorrectly the power to the accessory will flow trough the original fuse causing additional strain on that fuse. If the accessory draws alot of power and it has a larger fuse than the original fuse (say a 2way radio which i install) then the additional draw can blow the original fuse, you essentially fuse everything on both circuits with the original fuse. it can be a problem if the original fuse is something like airbags. very thorough otherwise.
+j Walls
Hi. Thanks for the thorough and well thought out comment. It's certainly will be a bonus to anyone reading this page.
I can't help but wonder in honesty if the major differences with these Piggybacks lie with the manufacturers. I get the impression you are informed and well aware, so I've no reason to disbelieve you, though personally in my experiments I couldn't duplicate the results you describe. So perhaps it's a manufacturer thing...
I've got two Piggyback videos now and I hope I've made it clear with those which way I would recommend fitting them. I do agree with you though - FIT THEM CORRECTLY FOLKS - as that seems to be the best way to avoid issues and again, a personal preference, I wouldn't over-power them. I'd restrict their use to 10 Amps and under. Anything else could tax existing cables, etc, so and separate, dedicated line would be better.
Again, thanks for your comment ; )
Geoff
+Geoff VegOilGuy rarely will it cause a probem geoff. it just means that when fitted backwards the power goes into the fuse holder through the output leg of the fuse tap then feeds the input leg through the original fuse. to help visualise this problem - if you trace look at your diagram explaining the path of the power through the fuse tap just imagine the power going through the output leg of your fuse tap. probably wont cause a problem unless the accessory draws close to the limit of the original fuse. trust me it can cause problems. my guys installed some backwards on a fuse controlling a light system on a school bus. blew out the original fuse when the 2way radio was used for extended periods of time. trust me on this one - think through it and you'll get it. really great video otherwise:)
+Kate Walls So I guess the real question is, which way is the right way? How can you tell?
ComPrt3
It's all about the power consumption. Have a look at the device you want to install. Read the literature or look on the device itself. Somewhere it should say, in Amps, how much power the device uses. Personally I'd recommend that if 10 or more Amps are required then a separate fused line is best. Anything less than this should be okay. Hope this helps.
+Geoff VegOilGuy Actually I was referring to which direction the fuse tap should be placed. It can only go in one of two ways. Which is the right way.
Can add original fuse 20 from lighter and 10 for amp?or i need original 20 and new 20?
The audio is wayyyy too low
So, how does one tell the correct way to insert the piggyback.
Hi Peter. That's a fair question. I'm not sure if I actually make that clear on this video. I know I did in my Fuse It video - ua-cam.com/video/8omZ545Cw1U/v-deo.html
If this helps, think of the red tail of the piggy (the wire that sticks out) as pointing the way out - "sticks out - way out" sort of thing.
A fuse holder is a bit like a U turn for electricity. The current comes in through one terminal, through the fuse, then out through the other terminal. If you know which terminal is which, you know you can safely point the tail of the piggy in the direction of the out. Sounds very confusing when I'm describing in like this.
If you have the time, check out the video I've mentioned. It's something of an auto electrics 101 but it does should how to identify a suitable fuse, etc.
Any problems or further questions, please do come back to me.
Geoff
Yes, there would be no difference in amps because a fuse is hot only... it's just a fused circuit that can only handle a certain amount of power going through it .. if that power is exceeded it burns through and breaks the circuit... 😁
If main fuse is missing and top fuse V wont work if backwards, it V is bgg using power from the other fuse
Hi! I have a question. My car didn't come with neither trunk nor glove box lights. So in order to add them, should I use one piggyback fuse holder for both lights (and the lights spliced together in one cable) or one piggyback for each light? They are halogen since it's an old car and LED lights really don't look good on it. Thanks in advance.
When adding a circuit to any existing circuit the caution here is the possibility of current overloading of the existing fuse supply wire. some cars have very light wire. On lightly loaded aux circuits it should be fine. do not try to run amps, driving lights, fridges etc in this way without relays and heavy bat supply harness.
+marcus mcc
Thanks Marcus. That's a point point well made.
Done very well! Plus, proved your point. Don't know why the manufacture constructed
the piggyback to NOT function when in backward with the original fuse missing as you
illustrated. Ideally, it should be a simple parallel type of construction that would eliminate
any orientation issues. Perhaps it was a feeble attempt to catch people's attention with the proper fuses going back into the proper places. Who knows? But I know it's safe and
plan on adding a plug to my car using this method. Instead of the wiring around a fuse
method. Bravo! Thanks again.
all this talk about piggies made me hungry
I accept much of what you say. the only comment I make is that,if put in the wrong way, yes a current will flow to the new circuit but..it will not pass through either fuse. The new circuit would in effect be drawing power directly from the feed to the fuse holder and will not be protected by a fuse unless the feed to the fuse holder is itself protected by a fuse prior to it arriving at the fuse holder. If I am correct then plugging the 'add a fuse' the wrong way round is NOT adviseable.
+Keith Bryant
Hi Keith. Thanks for your comments.
Yes, your quite right, it is BEST to fit these the correct way around and I hope I've helped explain the best way to do that.
The issue of "wrong way round" and "blown fuses" is something I covered in another video if you're interested. You can see that here: ua-cam.com/video/2mBa5rRZbCk/v-deo.html
But in short, as long as you're not over-powering these, to me they seem a fairly simple and safe device to use.
Hope this helps.
Best wishes,
Geoff
Nice video. I see the issue of ¨wrong way round¨ this way: the original fuse is going to feed its original circuit but additionally is going to feed the new circuit via its new fuse. Both circuits are protected but the total current of both circuits is going to pass through the original fuse with the risk of this blowing. Thanks for sharing.
The add a fuse will work for the bottom original fuse/device but if inserted backwards one of the legs on the add a fuse is dead to the new device. For new device to work with the secondary fuse in line, the positive side of fuse box has to be connected to the "active" post on the add a fuse, just as your second video demonstrated. The only risk is if you have 2 devices on this one circuit drawing a combined total current higher than the wiring in fuse box can handle. (Overheating). If you are careful what 2 devices you put on one circuit, you should not have a problem. Check combined amps of both devices.
Your looking to far into this, Piggy Back right way will work, Piggy Back wrong way wont get any power so wont work simple, the lower section of this device is irrelevant it will work any way round just the same as the fuse would on it's own.
Is it safe to use two different (size/number)(5,10 or30) in the same piggyback holder?
Cool video - thanks
Actually I never gave this a thought, until now.
But it is easy to detect - insert the piggy back fuse holder, with only the original fuse inserted and switch on. If only the original circuit works - it has been inserted the right way and you can insert the add on fuse and everything should work OK.
Totally agree with what you said.
I appreciate the experiments that you did on this.
Many thanks : )
I was hoping there was a way to see if you could blow the fuse, or more importantly, if fitting it the wrong way or with non matching fuses it might prevent the fuse to be blown as desired.
Like
Im planning on using this type of fuse tap to hardwire a dash cam so I can have it on when the ignition is on (using the Blackburn Power Magic Pro). In Blackvues installation video they do not add a new fuse to the tap, they literally just pull out the original fuse, put that in the bottom of the tap and plug it back it. Is this safe/should another fuse be put in the top slot and if so what strength? (The original fuses are 7.5 and 10). Thanks in advance!
Thanks for your question.
I haven't seen the video you mention so I can't really comment on it. When I was fitting my dash cam I saw a video from a guy who claimed to be a professional. He wrapped the bare end of a wire around the leg of a fuse... don't do that please! Loose wires in a fuse box are a recipe for disaster.
In truth dash cams tend to draw very little power so people often splice just about anything.
The best approach (and good practice) is to run a new line that's properly fused, that way you can be certain everything is done properly. If you have an empty (spare) fuse us that. If you haven't then a piggyback fuse is then next best thing.
Placing a fuse in the TOP means you have created a new fused circuit. If something blows a fuse, you'll know whether the problem lies in the Dash Cam or the other appliances. And THAT is what it's all about really... safely controlling electrical devices - being able to isolate individual items.
I hope this makes sense. Best wishes and good luck,
Geoff
So these are absolutely safe to take a trigger current for relay from high beam fuse, that should add very low current to existing circuit. Adding auxiliary high beams to my car and searching easy way to take trigger current for the high beam.
These are perfectly safe, yes. But if you're triggering a relay, and I commend you for doing so as I personally think that's always the safest option, you might not need one at all. Generally relays use very little current to trigger, so you can tap into an existing circuit.
Good demonstration! It can be quite confusing for some that the piggy back in correctly has 2 separate circuits from the same voltage source.
Excellent demonstration!
Good afternoon, what about on the micro fuse 3? Is that possible to be inserted the wrong way
Thank you this was useful. I need to wire an oil temp/pressure gauge.
Thanks for this exhaustive test. I was questioning my own judgement for a bit. I just wanted a convenient delayed accessory feed to control a "Charge Guard" without having to tap a factory harness. These add-a-fuse kits are the way to go. The owner's manual usually always tells you which fuses are switched and which are always hot. No dodgy splices in a factory wiring harness. No hunting with a test light.
I think that there is no wrong way of putting it. It's just a different application. First if you want to split something in two - let's say put another cigarette lighter. Or second you want to add something , like additional lighting in the trunk. If the original fuse is blown/missing/ it should not work at all if you are adding stuff. Just like if you turn it the wrong way around. So for me this is not the wrong way, it is the right way. If the original fuse is blown, this means that something in the original wiring is wrong and it is not working. So why should the additional wiring be working. It could be dangerous. But if you want to split the cigarette lighter, then you would want both of them to work, so this is too not the wrong way. For me there is no wrong way, just a different application and it gives you the choice on how to use it for your purpose. Greate job there.
I need to power Dashcam external battery pack which has a 20Amp fuse..(the battery also feeds the dash cam)..... If the original fuse is say 15Amp would the new Load(additional) blow the original fuse? Lets Assume piggyback is connected correct way..? So my question is Must the Original fuse be Larger than the New fuse? According to your tests the fuses are independent from each other assuming the piggy back is inserted correct way would this be ok?? So to clarify a bit more IF the piggy connector was fitted in correct way round. Is it ok for the New circuit fuse to be bigger than the Original fuse rating??
Thanks for any advise..
Hi Andy. You've certainly got the right idea in mind.
It's not a case of how big or small the original fuse is. It's more a case of will your extra drain on the circuit cause a potential overload. This video might help...ua-cam.com/video/hvi-Xv9wFOI/v-deo.html
20 Amps is quite an extra load to place on any circuit. You may be better of trying to access an item fuse line...?
Hope this helps.
Geoff
Is it safe to use piggyback for after market headunit install?
A brilliant video which has given me the confidence to correctly wire accessories to my new motorbike.
My question it's this.. Im going to instal a extra USB charged for my car. the red ( positive cable ) from the USB charged goes into the red ( positive cable ) of the piggyback. What do I do with the black ( negative ) cable where do I tap that one?? thank you for the help
Hi Evandre,
Thanks for your question. Yes, I think I can help you : )
Try this video I did a while ago - ua-cam.com/video/8omZ545Cw1U/v-deo.html
A few people have been kind enough to say I should rename it Auto Electrics 101 or similar. I like to think it gives a simple introduction to the subject that should more than answer your question.
Any problems, let me know.
Best wishes,
Geoff
i think that if the piggy installed at the circuit the wrong way and theres a short in the external circuit it will blow both fuses.
'dosent it?
That hasn't happened in any of my tests thankfully, so I don't think it's an issue : )
I haven't found any peer reviewed data to suggest that piggy backs are unsafe, this would be the closest thing I have come across to suggest, more than speculation or mere idle wondering, that this scientific analysis, as crude as it may appear, is the closest thing to any peer review data that suggests that these units are in fact safe. See this is exactly how data and evidence is proved or disproved. Proper tests that can be reviewed by its peers. Great test and thank you for the data and visual aides to help digest the information! Keep up the great work.
Many thanks. I don't claim any special knowledge or skills... but I try my best : )
Hi there
I've just brought my first car and i'm replacing my radio. Im going to tap it into the cigarette lighter slot which turns out not to have a cigarette lighter in. The original fuse that's in there is a 10A so will adding another 10A fuse to the piggy back be ok. I'm a complete amateur when it comes to things like this so just wanted some reassurance. Not sure if i'm going to get a reply as you posted 2 years ago.
Dan
Hi Danny... I'm still around posting videos mate : )
I'm surprised there's not a radio already in the car... and if one has been taken out, there should be a wire harness left behind - simple plastic connectors you can just push together. It's VERY unusual if there isn't one of these unless the car is old.
Cigarette lighter sockets are a good place to power from, but to avoid overloading the wiring, don't run the radio and the cigarette lighter at the same time. Better to remove the lighter (not the socket obviously) to prevent this occurrence.
But I still think there may already be a harness there for you to use... You said REPLACING so I think it's there... if it doesn't fit the new radio, check with a dealership for a adaptor kit. This is just more simple plug in fittings converting older sockets to newer ones : )
@@vogmanHi
Thanks for the fast reply mate. Yes i'm replacing the factory radio with a aftermarket one. Yes your right there is a old wiring harness but there is a red wire from the radio that's not connected to the harness that needs to be connected to an ignition point. I have two free fuse slots in my car but i don't have a fuse box layout to know whats what. I've researched pics of my fuse box with fuses in places where mine doesn't have them which has made it confusing . I cant risk just using one of the them if there has been a fuse removed in the past by a dealer or a past owner.
I checked again and the cigarette lighter fuse is a 20A and I would need to add a 10A for the radio. I know u said not to go higher that a 10A. Do you think it should be ok or not safe
Sorry for bombarding you with questions but I was just thinking the cigarette lighter has a 20A fuse and I plan not to use it so can I swap that fuse for a 10A and then my second fuse be a 10A. Sorry if that doesnt make sense as I’m a dummy when it come to this.
Hi again Danny. I wish I could help you but I'm hopeless at visualising things. I'm the sort that has to be there, to see things with my own eyes.
To me the harness should give you everything you need, but you mention a Red wire that needs connecting to an ignition source. This sounds like it's on the new radio...? But all of this sort of thing is included within that harness.
I generally say if in doubt don't do it. If you haven't got a friend who can help, look for an auto electrician or a local garage. Sure it will cost you a little, but much less than a new radio if things go wrong ; )
Excellent test and explanation. Thank you
Many thanks 😁
Great and very clever video. It was of extreme assistance in answering my concerns.
Many thanks
informative, but was the voiceover done in a vacuum?
piggy has to be put in correct way because if you put in backwards and you have a short it will not blow the fuse and you run the possibility of burning up your lines thru your car
Thanks for your comment.
My tests showed no evidence of a short - just a loss of power if the original fuse blows. This is a nuisance but not a safety issue.
If used sensibly, they're fairly useful items : )
If they were not safe the lawyers would have sued the companies that make them, out of existence. A lawyer would not pass up a chance like that you can bet on it.
Well said William. These things have been around for years now...
: )
what are those white connectors you are using called?
Much easier to just use an ohm meter to test for continuity to different legs with and without fuses.
I believe the only issue it would be to overload the wire supplying the power to the Piggyback Fuse Holder.
by tapping into a fuse line that uses a 10 Amp fuse chances are that the wire supplying power it would be rated at 10 Amps maximum hence the 10 amp fuse.
If you add another item drawing 20 Amps from the same supply wire you'll risk to burn the wire supplying power to the Piggy Back Fuse Holder
That's just my thought
Cheers
+Max Germasi
I agree with you Max. That's why I personally don't recommend using them on anything exceeding 10 Amps. In such such a separate line is the best way to go.
Thanks for your comments.
Geoff
@@vogman I realise it is 3 years ago but IMO that depends on which way the piggyback fuse holder is plugged in, right? The 'tapping' can happen at the side which supplies the current in which case it is possible to overload (at least in theory) that wire, but if it is tapped from the side that protected by the original fuse then you cannot overload the supplying wire but of course then the 'original' fuse will see both currents and that may blow it. In real life I would expect that the wire supplying the current to the fuse is supplying all/most of the fuses in the fuse box so very unlikely that you can overload that. But what do I know, just second guessing the engineering logic... :)
I just came across your videos Geoff, and I think you make the subject matter easily understood and illustrate things clearly. I´ve only recently started learning about electronics, but what you are testing in this video seems logical to me, meaning you presented evidence in favour of the (my) theory. The issue here should be how the current flows inside the "fuse tap". Then it makes perfect sense that the circuit is broken if you blow/remove the original fuse while the fuse tap is mounted the wrong way around.
+Berserker
Hi Berserker. Thanks for the kind comments.
Hi good explanation of the piggy back fuse holder.
I’m just about to use one of these on my van and purchased the correct size of piggy back fuse holder.
When I removed the original vehicle fuse I was surprised to find it had 3 prongs, found out it’s called a micro3 fuse.
Just wondering why it has 3 prongs instead of 2.
Hi Anthony. You're right about the name. Micro3 fuses are becoming more popular as they're space saving and capable of handling high temperatures. If I recall correctly, they're basically two fuses end to end. So lets pretend the two fuses are 5 Amps. That means the fuse is a (5 + 5) 10 Amp. BUT there's also a centre terminal... if we connect via the either one end and the centre it's only 5 amps. At least I think that's the general gist : )
Hello there. Thanks for the video, great explanation. I am looking to wire a usb charger to a motorcycle and would like to use one of these piggy back chargers. The fuse i will be replacing with the piggyback charger is a 15A fuse so i will use a 15A fuse in the position of the old fuse in the piggyback. My question is what fuse will i be able to use in the new fuse postion? Seems that you use a 10A fuse. I am trying to power usb charger that will give power to a GPS and iPhone. Will a 10A fuse be enough? How can I figure out what fuse i need?
Thanks.
Hi Nick. Thanks for your question and kind comments.
The answer SHOULD be available to you on the device itself. Somewhere it should say on it the amount of current it uses in Amps. The trick with fuses is to select one that is HIGHER than the amount the device requires but not by too much. If you go lower, you'll simply burn out the fuse. For example, if it uses 3.5 Amps, then a 5 Amp fuse would be ideal.
It will probably work with a 10 Amp fuse and I can't imagine a USB charger using too much juice, but I'd prefer you to check the device and make the best possible choice for you.
As for which to Piggyback from, have you seen my FUSE IT video that should hopefully help you pick a good fuse? If not give it a whirl and let me know if you have any questions.
Hope this helps.
Best wishes,
Geoff
Thanks Geoff ill give it a shot.
That was very informative. Appreciate that. My fuse taps blue end got cut. So its gone. If i just tie the wires together with that end will it work.
Hi Raj... to be honest I'm not a fan of those connectors. I cut mine off and solder them : )
Hi great video can you advise please. I want to hardwire my dash cam with a piggy back & it already has an in line fuse. Could this cause an overload? Thanks
It's common practice for suppliers to fit an inline fuse. Typically if you remove it, you invalidate the warranty. Keeping it won't cause any overload issues but it could make finding a blown fuse more tricky if that ever happens. Just remember it's there : )
Thank you for putting this in layman's teems. I've got no experience with electrical and other videos I've watched don't explain clearly why it works or doesn't.
Happy to help : )
It's not about power loss it's about safely handling high current loads.
You're spot on Bill. I cover this very issue here - ua-cam.com/video/hvi-Xv9wFOI/v-deo.html
I've had one in for years. Safe if done properly >:0
Can i first do 10a and then 20a or the first must be higher or same like the second?
The size and order of the fuses doesn't matter. But don't overdo it or you risk burning out your wiring : )
Thanks for the demo, it's really helpful..
Is it safe to use for LED light bar?
I have 120W led light bar, how many amp it will draw?
Ah... maths... and so early on a Monday morning : )
Assuming your vehicle is 12 volts, Power = Current x Volts so 120 = Current x 12 so 120/12 = Current
That's 10 amps.
You appreciate there's always a risk in offering advice like this - I'm not there with you, seeing what you see, etc, so I could be wrong. I think you should get away with 10 Amps in a Piggy, but go slow. Do it, test it briefly. Test it a little longer. Keep an eye on it for a while.
Great video, VOLUME needs increasing though , can barely hear you with phone full volume .
Me too, I thought it was my several year old 6s Plus 😂
Is it ok to tap in to o2 or oxygen fuse ?
theres no fault with the meter, the thing is that the circuit you are building is a parallel circuit. the voltage stays the same but the amp get divided into the 2 lights bulbs. but i guess those fuses are diferent, one will pass more current than the other one because it will act as a resistor depending on the thickness of itself
Thanks for that Steve.
Ure welcome
Which socket on the piggy back works as the original source and which acts as the new circuit?
Hi Ryan. Try this video. ua-cam.com/video/8omZ545Cw1U/v-deo.html
It should tell you everything you need.
if i use this piggyback fuse holder do i need a spare fuse or put just the fuse i took out?
The "original" fuse goes in one slot of the piggy holder, connecting the original circuit.
The NEW fuse goes in the second slot.
Hopefully the video should tell which slot is which.
Hope this helps ; )
I have a question if my original fuse is a 10 amp min and I'm trying to tap , what # amp fuse should I piggy it with?
The size of the fuse you use is determined by the item you're fitting. For example, if it requires 3 amps and you fit a 1 amp fuse, the fuse will always blow, and if you fit a 10 amp fuse, it will never blow, but the item you're fitting could be damaged. Look at the item itself or any information that comes with it. It will generally tell you what size fuse you should fit : )
Try this video I did. It may help : )
ua-cam.com/video/hvi-Xv9wFOI/v-deo.html
@@vogman thanks!
Happy to help.
Thank you just what I needed to run the power through the ignition for the parking sensors I received for Christmas.
Glad I could help : )
you forgot to mention what fuse should i use in the new circuit, the same Amp fuse as the original or a lower Amp fuse? if it is a lower amp fuse then how low it can be? thanks for your help ☺
Hi Cesar.
It's very hard for me to be able to say which fuse without being there with you as all vehicles are different.
Ideally look for an empty fuse holder or a fuse that's not used much. For example, the fuse to cigarette lighters should be perfect, as long as you're not already fully taxing this circuit.
It doesn't really matter whether the new fuse is higher or lower than the original, but keep an eye on the total current being drawn. This video may help - ua-cam.com/video/hvi-Xv9wFOI/v-deo.html
Any problems, let me know : )
Geoff
VegOilGuy thanks a lot for your help
HI JEFF
Thanks for this. I've always thought that plugging it in backward would supply unfused power to the added load. Of course now I see that plugging it in backward will actually only cause the lower fuse to carry the load for both circuits and the top fuse will only protect the added circuit. Plugging it in correctly will give you what you really want which is two circuits independently protected by their respective fuses. It's really simple actually but this video made me consider it properly. Thanks.
find a way to measure the current passing thru the original fuse when the piggyback is connected wrongly, sure it would show you a different value
I really can't see any reason why it should : )
There's a lot of paranoia about these devices and I really don't know why. I'm guessing a lot of clumsy DIYers have wired things badly and wrongly blamed these Piggys for the results. It's like blaming the Car when the Driver is drunk.
As long as you don't overtax the wiring prior to the fuse, these are safe and simple devices.
Hope this helps.
@@vogman im not saying its not safe, just want to emphasize that the current passing thru the original fuse will be the sum of the currents used by both lamps, using some electrical formulas/theory...as long as the current on the fuse is within its rated capacity, then you have no problem
Ahhh.... I'm with you. Yes. A lot of folks fail to take into account the extra current being drawn on the parent circuit.
Nice one : )
I know the new fuse you're adding needs to be of a lower amperage than the original fuse, but does it matter exactly how much lower the new fuse needs to be???
Hi Adrian. It's all about the wire size in truth. The sizes of the fuses are irrelevant if the wire feeding them isn't up to the task.
I appreciate that may have confused matters further, but hopefully this video will clarify things nicely for you - ua-cam.com/video/hvi-Xv9wFOI/v-deo.html
If you've got any further questions, let me know : )
Thank you. The video answered my question perfectly. Amazing videos. Great work.
That's very kind. Thanks : )
Brill! Thanks.
No worries 😁
On picture where the fuse is the pins what's that in & out it's that positive an negative power an ground which one is
It's been a while (it's quite an old video) but I'm probably referring to where the power goes IN to the fuse and then goes OUT of it - the fuse bridging the two points. You might find this video helpful - ua-cam.com/video/8omZ545Cw1U/v-deo.html : )