Earth Electrodes Part 2 - Installing, Loop Impedance Testing
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- Опубліковано 12 лип 2024
- Installing an earth rod with cover, then testing it using the loop impedance method.
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Enjoyed that John would love more videos like this. Thank you for taking the time to create the content.
did your eyes pop out when you saw the size of JW's hammer? you must have been at least a little envious😀
instaBlaster
Didn't realise that J.W. had legs.
I was shocked! Sorry, surprised. I couldn't be shocked as I'm watchin on a correctly installed youtube circuit and the RCD tripped.
Probably just CGI legs.
Nice to see you on the tools John 👍
Another excellent Video by the great JW. The best.
Great, thorough and easy to chew explanation. Thanks for the upload, looking forward to next one!
Your videos are always so clear in their explanations and really, really helpful. Thank you, very much!
Very informative John thanks for all your hard work uploading these useful videos
Thanks for taking the time to do this! Enjoying this series! In Belgium, the earth electrode (everything is TT in Belgium) should really be
Very well timed series, I have my first tt system to deal with in the new year and I had been wondering about testing procedures 👍👍👍
As always, a much appreciated video.
Thank you.
Excellent video John. Thank you.
Excellent as always john....
Another very useful Video. Thanks John.
Like a lot this test. Very crystal clear explanation and precautions. And that was 106 Ohms with only one rod , good.
Until the summer, when a few weeks of drought causes the resistance to increase. Moral: only electrocute yourself in the rainy season.
(1:10) - You just can't beat that high-voltage sage.
It's simply got quite the unique flavour.
I'm definitely installing an earth rod in my herb garden.
Just to see if it affects the flavour of my other herbs.
There is a distinct zinginess to the Rosemary that comes from my friend's high voltage herb garden.
Can't wait to try out the same on my own.
All the best and way to go !
>
John.
Your a machine. Loved the one hand method of driving the electrode in to the ground.
Keith Johnstone Terminator - Model JW18THEDITION
Exellent demo sir.well done.
Great video EFLI for beginners
Good video, very well explained.
I have just installed an earth rod and wanted to test it. To do this I used a 100 watt light bulb a volt meter and a current clamp. 100 watt bulb across live & neutral measured 229 V & 0.425 A (volts x amps = watts 97.33) so then worked out resistance of circuit (volts divided by amps = resistance) say 539 ohms. Then did 100 watt bulb across live and earth rod measured 234 V and 0.416 A (volts x amps = watts 97.34) so then worked out resistance of circuit (volts divided by amps = resistance) say 563 ohms
. So extra resistance in circuit caused by the path through the earth = 24 ohms.
Thanks John
Nice one JW.👍
Enjoyed that. Thanks 🙏
Great video
Cracking video JW you never mentioned to null the 50m test wire to the earth rod before measuring the impedance, but you did mention it was around 1 ohm later on. Looking forward to the 3 wire method 😊
He was using the coil to simulate the resistance of the earthing conductor from the consumer unit to the rod so therefore wouldn't null it in this instance.
In reality you wouldn’t be using the wander lead, you’d have an earthing conductor from the electrode to the MET. The test being carried out between the line and the (disconnected) MET end of the earthing conductor.
I’m not even sure you can zero the leads for a loop impedance test on a megger
Looking forward to the 3 electrode test video👍
I LOVE YOU JHON!!!!
Will be fun installing that silly earth rod cover/box on the street side.
very helpful
😲 JW has a lower half!
funny thing, tonight i put the rod next to a sage plant like you did, and i just saw your vid and was like "did he put a rod next to a sage plant too!!?" xd
I'd call that timber a mowing edge, thus quite functional.
My brother was quite well known in the road lighting world. He did some of the M4 many years ago and it's not changed even for LED's. The stories he told me about getting earthing spikes through testing were often father funny. On building sites for say large factories or office blockes, etc the used to position the tempory toilet over the ground spike installation. Two buckets of course, one with holes in the bottom. When all cleaned up and the few hundred gallons of 'waste' they passed every time. Good idea for high resistance sandy soil on top of a hill - but for how long ?
Try installing a rod like that on Portland, you'd probably need to drill a hole first given the amount of stone there.
we know from a previous video this installation has a tns earth . turn off the main switch on the consumer unit and place a volt meter beween the end of the fly lead from the rod to the met bar . then do the same with a milliameter, if the soil is acidic you may get some suprising results
That reminds me of a trick we'd play on the new Post Office trainees....send them outside to water the telephone exchange earth., well they've got to be watered, reduces resistance. You wouldn't believe the problems we had with PABXs, reclaimed land, bad earths and electric trains nearby
Well explained JW, plus you have very nice test instruments...
Hi john, great video so would that reading be your ze?105ohm) if so do you factor this reading for your zs?
Thanks
Yes, that's Ze. Add on the circuit resistance for Zs.
Hey John, is there any way to measure the impendance ( resistance ) of a given earthing system ( say daisy chain 4 rods ) using the multimeter ? If so, how to ? In my area the specialists saying about a value of around 4 Ohms of resistance but i don't have a special tool to measure. Thank you.
Hi John - Great Vid, Would you need to null the long lead before doing this test this way?
Yes, either with the tester null feature or just measure the lead resistance and deduct from the final result.
Like the matching outfit
The sparks in the UK always are dressed in nice and official looking attire.
Those strides are pretty swanky.. If I had to hazard a guess they'd be Dickies, at least they do a pair very similar for about £20
Thumbs up to John for trying to reach a more diverse younger audience 👍
I would be interested in knowing how this compares to grounding rod installations in the United States. Electrical code differs from state to state though. Our electrical installation is 50 years old. The top of the grounding rod is exposed about 4 inches above the surface where the ground wire is clamped and enters into the electric meter. There is no containing box, and there is just one rod. The rod should be 8 to 10 feet deep. Communication grounding for telephone, cable, and satellite is clamped to the ground wire as necessary for electrical code.
Small bug is inspecting your installation 😀
Wood Louse
2:40 I hope you installed a small ladder to allow the wood louse to escape - I think it would have a tough time scrabbling up the plastic sides :-)
It started at 2:25. was inspecting the soil quality
aww
They can dig and tunnel quite well, no problems. Like an insect version of an armoured car, but with legs.
Great video makes it all look so easy. If you needed to install 2 rods how far do they need to be spaced apart
Minimum of 2x the depth of the rods. Further apart if possible.
@@jwflame ok mate cheers
Also mate not to do with this. But it's about bonding plastic water pipe coming in basment then copper through the floor and to rest of property. How do you test if it needs bonding or not
To determine if pipe work is extraneous an IR test is carried out between the pipe work and the main earthing terminal. A reading over 22K ohms means it isn’t extraneous. Be aware that attached items may cause low readings such as class 1 appliances.
@@gd-bq7em Just bond the hell out of all of it. No harm done.
Cool pants.
Won't doing this cause random rods appearing from the ground for people in Australia?
The rods melt half way. ;)
our rods are 1.4 mtrs, most the ground is hard so after taking a full day to bash in 1.2 mtrs, you are left with the typical 20cm or so above ground :)
But usually in places where people and lawn mowers cant easily reach.
some builders are awesome, I saw one guy attach what I reckon would be 16m sq earth from a generator to a ground stake - a 30cm stainless roasting type skewer :D
@@robbedoeslegrand236 must be why there are Copper mines in Australia 🤔
Rookie mistake installing box before electrode.
(1) dig hole a bit big and test for fit of box
(2) install electrode
(3) put box over top and backfill.
Reason being it's easier to hammer down without smashing the box - and if earth really hard and you miss with lump / sledge hammer you again don't smash the box.- plus if you decide it needs to go somewhere else to get a better reading again it's easier to work without smashing the box.
Thanks that makes good sense!
If the soil is hard clay or silt, filling that box with water will soften it up and make the driving easier.
Hi John, any advice on selecting the appropriate diameter of earth rod? I presume the larger diameter rod has lower loop impedance due to larger surface area but in practice is there a balance to be struck between cost of rod and loop impedance required/achievable? Was that a 5/8th inch rod you used in the video? Thanks.
Next to no difference in impedance on diameters, much bigger difference in depth it's set. Thin rod for soft ground, thick rod for harder ground. Yes that was 5/8", lord knows why they are still imperial. Probably so they can sell you the bolt for three quid.
@@markrainford1219 haha, yeah you're probably right about the reason for being imperial! Thanks for the insight on when to go 3/8" vs 5/8".
So in the UK, do most homes rely on an earth rod as shown in the vid? Secondly, does the consumer unit not have a earth conductor that traces back to the supplier/council ?
Most homes have a TN-C-S supply, which uses the neutral as the earth conductor - 2 core cable to the property L and CNE, 3 inside the property L, N, E. N&E linked at the entrance to the property.
Earth rods are only installed on TT supplies, which are fairly uncommon. All TN-C-S supplies should have an earth rod as well, but that is almost never done.
@@jwflame Give this man a Bells Scotch for the good vids. Keep it going, you make electricity interesting.
Hello is the next test similar to testing lightening protection ?
John on this 2H test do you put the green in the green on the tester and red in red?
Yes.
50 meters of copper wire ~ 1/2 Ohm or less depending on gauge.
He did measure it in the MFT1741 review. It was about 1.01 Ohm. The data sheet for this 50 meters reel doesn't actually specify the wire gauge or the current limits, but I would expect it to be 10A or 15A rated, similar to what other multimeter leads are using. So probably 16AWG. Maybe it marked on the actually cable insulation. You also need to include the contact resistance on the slip ring on the real, and contact resistance on the rather poor alligator clip on this real, which can add probably another 0.2Ohm.
The house in this video appears different in perspective from the one where you do the test videos by the shed?
Different house
@@jwflame Is your Shed in next doors Garden ? Or near there ? according to Google Maps the House next to yours appears to be Derelict.
JW, I presume you had permission from the Garden owner? I can imagine them stood there, trowel in hand the following day and muttering ..."where on earth did that come from?" where on earth. Earth? Get it. Oh, I'll get me coat.
How come sometimes on a TT system you can get a lower Zs reading then the Ze at the board.
Can I use a multi meter to test the resistance from earth and neutral?
Stupid question, but would you get lower resistance in wet soil?
usually need to stack 6+ electrodes to get about 30 ohms
I Must have had my head in the sand! 'Power Drill' I hear. Just googled and came up with a selection of Bosch or Dewalt 'Ground Rod Driver' from amazon and eBay. Anyone have any recommendations on what and where to pick up, before I hassle my wholesalers. Thanks
Excellent, as always! JW I do have a question though. What would you do if the test failed and you were to find that the soil conditions in the area of installation was not very conductive at all, like sand, gravel, etc? Would you have to drive more bars until you get the proper amount of bonding to earth that is needed or would they have to come in an excavate some area to install a mesh or some sort? Very interesting stuff and seeing it actually in the field now brings about more questions! Thank you!
Start off by screwing a second rod to the first (twice the depth). If the impedence is still to high then install a second rod.
Is the water mains used as ground (assuming no plastic water mains)?
Not permitted since 1966. Before then it was fairly common to use it.
@@jwflame According internet in the Netherlands since 1975. It is possible still in use in older houses as long the water mains is not replaced by plastic pipes.
JW, why are you measuring between L & ER ? Surely impedance between these should be Mohms ?
pmailkeey The earth fault loop impedance is measured in ohms. The electrode has a resistance to mother earth, in this instance we only know it is less than 106 ohms. Soil conditions and rod length are two things that effect the rods contact thus resistance. If JW was to pour brine on soil around the rod the resistance should decrease.
The test measures the full loop impedance path, from the flylead to the electrode, the electrode through mother earth to the electricity board electrodes, back to the transformer, through the transformer winding, through the line conductor back to the main switch.
Yes I dont really understand this. Between live and ground is like an IR test and would expect to see MOhms too. I think we must be missing something here.
I understand that similar if I were doing Earth bonding test saying using a Clarke 25A tester (industrial enclosure not houses) I would be expecting extremely low ohms between a ground point and the earth point on test (ie a earth stud) but this appeared to be live to ground.
@@cumberland1234 Ok - getting it a bit now - having remembered E and N are usually connected together. However, unless all other connections between L and E on that transformer's secondary winding, we have no proof of path. L will be connected to N in many places through electrical equipment switched on. Connections between N and E could be anywhere and also numerous.
@@davidlenton2366 On the circuit the substation transformer supplies, L is connected to N via the substation transformer secondary winding and all switched on electrical items being fed from the substation. So we have an N-L connection. Now I also believe it's common practice to link E and N together. Hence we have a connection L to E - a circuit - in this case of 105 ohms.
While we can identify the circuit we're playing with, the bulk of it is a completely unknown circuit. We don't know how many other earth rods in the area are connected to E or N. We also don't know how many electrical items that are switched on and connecting L with N.
This test, therefore, appears moderately valueless. Unless we assume all other connections are of zero ohms - which won't be the case but could be very low.
On the basis E is connected to N (low resistance connection), there would be more sense in measuring N to Earth Rod.
@@davidlenton2366 Our expectation of Mohms is from disconnected equipment - tests carried out between wires not connected to anything - to do the tests, they're always disconnected from supply. Measuring supply L to E is what's being done differently here but I still think supply N to ER would be a better thing to measure.
Imagine you could keep adding lengths and hammering until you reach the earth's molten iron core.
How come there in no RCD on the left row of the consumer unit? I see a buch of 6A MCB and also a 40A. Is it because it is an old installation and at the time of install the Regs did not demand an RCD protection for that part of the installation?
MrMatiDi It looks like a 16th edn installation, as with all sparks none of us do upgrade work at home each time the regs change until we are forced into it!
@@cumberland1234 The cobbler took his children on a busman's holiday, so he was too busy to upgrade his consumer unit.
Up until a couple of years ago my fuse box was an old 3036 wylex - it didn't give any problems but wasn't ideal. It is now a metal MK board with a mix of RCBOs, RCCBs and MCBs along with the bell transformer. At least I managed to sneak an isolator in the meter cupboard when the meter was changed to a smart meter - unfortunately there is not enough room for a Wylex Rec 2 isolator as they put the comms box bit in the way.
The biggest issue at the moment is MK don't offer a SPD and are dropping their CU range. Maybe in about 20 years time I'll upgrade it to something modern!
@@cumberland1234 Fair enough, but that also would mean that in case of that 40A connected item becoming live, someone could potenatially get a very bad shock. Am I getting this correct?
@@MrMatiDi As long as the earth fault loop impedance it met it shouldn't be a problem, the circuit should disconnect within 0.4s hence not cause an issue to a person. There are two ways to protect persons, limit the voltage or limit the duration of the shock.
Each edition of the regs increases the level of safety, a 40A MCB is probably a shower or cooker.
If it is a shower, coupled with supplementary bonding which, when required, under the 16th edition regs is limiting shock voltage, the duration/voltage of a shock shouldn't be an issue.
For a cooker, duration shouldn't be an issue.
Nowadays, under the 17th or current 18th edition regs, a shower (and probably a cooker owing to installation method) should be on an RCD, a L-E short should go within 40ms.
Like listening to noise torcher
I assume the Megga tester measures the Open Circuit Voltage between Line and the Earth rod lead Voc then applies a short circuit Live to Ground and Measures the current flow from Line to the Earth rod cable. Isc Ze is then calculated as Voc/Isc and displayed.. Can this not be done then with an AC voltmeter (first test measurement) and a current meter (or volt meter and a current clamp to measure current) as second test measurement . Then do the simple maths to calculate the resistance Ze?
I wish it was as easy to drive anything in our soil, we have rocks with some clay as soil 😢
Very difficult to get under 100 ohms in the Poole area .
Instead, may I suggest the pool area ;)
Andrew Hasted, What would the reading likely to be during drought conditions ?
I thought the standard earth resistance is 5 ohms
very good thanks a lot
I think the resistance should be less than or equal to 5 ohms
WHEN CATS FART THEY STINK AWFULL BUT YOU CAN NEVER HEAR THEM DO IT
No hard hat , safety shoes, or harness tutt tutt tutt
Disappointed no Family Guy workwear