Earth Electrodes Part 4 - Testing in Dry Soil (June vs November)
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- Опубликовано: 31 май 2024
- Testing the earth electrode in June, to see if the resistance has changed due to the soil drying out. This was installed and previously tested in November when the soil was very wet, as it had been raining almost every day for several weeks.
Other episodes in this series: • Earth Electrodes
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Nice to see consistent readings across all 3 different test arrangements/setups.
I was unaware until I saw your recent video on EV charging that if your rod is within 5 metres of a “street” pme rod (with a broken pen conductor) then a dangerous voltage could appear on your rod and in turn all exposed /extraneous conductive parts within an installation! Great videos John keep them coming👍
Quite remember the video on november for requesting this ... Nice that it changes but keeps in specification on dry season. Thank you.
Nice video John,
1. I like the fact that you highlight soil resistivity in different seasons.
2. The accuracy of 3 lead (LOW CURRENT) testing is always a consideration, especially where physical contacts of the RCD itself might come into play.
Thanks again for keeping us all focused on the physics and not the politics!
I had it recently when testing the Ze on a TT system in the dry weather the reading was over 350 ohms, went back a couple of weeks later and the reading dropped to around 190 ohms after it had been raining.
The main switch on the consumer unit is an Rcd device.
Great video, am watching on my tea break 👍
Thanks for sharing 👍
Great video very clear information
Well done
Great video
Waiting for the video of you doing backflips on the trampoline !
He's not wired himself up correctly for that yet.
When earthing a property/hosuse, does the earthing wire go to the main meter only or does also go to every room? If it goes to every room, what do you connect the earthing wire to?
Hey does anyone know how to locate missing earth cpc in lighting circuit ? Basically there is no continuity from CU to first floor .The Problem is that all light fittings and switches are connected thru JBs which are somewhere in the attic under insulation and stuff . At this moment impossible to find .
John this fall of potential method (wenner approach) is becoming more important with the increase in outdoor power supplies sheds and EV charging. Most young electricians don’t really get into the weeds on this but need to.It’s not just moisture and temperature but also the nature of soil types (rocky, gravel, sandy) and contaminants (ie salt content or other contaminants like oil) or also mineral content that affects soil resistivity. It’s very helpful you have shown the testing protocol. Would have loved to seen a soil resistivity curve. Of course more detail work would require calculation methods and then you get into calculus.
How about if the test rods went in a different direction. I am current and thus resistance is recorded but feel it will vary.
Hi John, In your last video on car charges you noted that most supplies are probably TNC-S nowadays even though it might still have the old lead cable supply that looks like a TNS, whats your view on exporting earths to outbuildings in such a scenario? TT with an earth rod or just export it anyway and bond.
Depends if there are any extraneous conductive parts in the outbuilding - if not, then just using the PME earth won't add any additional risk and bonding is not required either.
About to watch this... Fingers crossed for the return of the cow :)
Q, Is it possible/practical to do a resistance test on a TT system, between the incoming Neutral and your Earth rod.?
This would measure the soil resistance from the rod, back to the transformer earthing.
I ask this, as it could be done without that very expensive test meter.
I could use a high current DC source, and a DC clamp meter.
I expect there may be some sort of residual AC voltage on it, but at a very low current value.
Am I missing something.?
In theory yes - one possible problem is the neutral in some systems won't be at the same potential as the earth electrode, which would affect readings or could be hazardous in some instances..
@@jwflame I did do a voltage test between Neutral and the new earth rod just installed. It measured about 230mv AC. All RCDs and MCBOs trip correctly, using my old Robin meter.
@@jwflame would that a Ze test scenario to also have the tester in safe mode for reading incoming mains voltage.
John you’ve done a lot of work on safety related electrical issues. However given the growth of modern DC and AC device and smart devices with greater use of electronic components power quality issues are going to become more important. Hope you do a series of videos on power quality issues and using testers to look at these issues and devices that can address some of these problems at least in a residential setting.
Is it possible to do this without the "Tester" ?
Hi john , how come the cooker socket has no rcd protection? Its a tt earthing system? You did the test on high current if it was on rcd it would have tripped?
Older installation, when outlets for dedicated appliances didn't need RCD protection.
@@jwflame hi john thanks for the reply 👍 just a thorght when testing to the 18th edition would this still comply many thanks ?
Do you think the corrosion of the copper rod could cause an increase in impedance over time too?
It would eventually, but that is likely to be decades in normal situations.
@@jwflame Thanks for the reply!
Sir I install earthing rod with bentonite powder after how many days I take final result now rod is giving 6.5 ohms. Please reply me
why don´t you just keep testing until you reach a stable result?
Are we maybe getting to the point where the regulations will be changed so you have to have several earth rods for example at the front and back (side) of the dwelling and of course all cross bonded particularly with things live EV charging points?
Great comparison. You forgot to add a one more test with 3 electrodes and using salty water to wet the soil around the temporary electrodes. I wonder how much it would lower the values.
If it's staying consistent I don't think it would make any difference, middle electrode is mainly for voltage, used to subtract the resistance of the far electrode from the resistance of the ground rod.
Once the current gets far enough away from an electrode, the resistance of the soil should become negligible.
The soil may be a million or whatever times more resistive than copper, but it's also has huge cross sectional area, assuming it can spread itself out over a wide enough area it can travel miles with tiny resistance- it's like having a conductor with a cross sectional area in the millions or billions of mm^2.
Wetting is just to shrink the "near electrode" region of the far electrode so it doesnt overlap with the grounding rod.
If you're not probing in that near electrode region, value given should be independent of placement of the middle rod, and the resistance of the far electrode.
I'm sure there should be a hook and chain behind the oven to prevent the gas pipe being over stretched.
Never seen that done to be honest
There should be a chain or other stability device. There should probably be an extra pipe clip on the rigid part of the gas pipe as well.
Even most electric new cookers come with a chain attachment as well now
@@paultipton743 What about dishwashers and built in ovens ? Are we chaining everything down ?
@@millomweb
it is to prevent theft
Curious to see what the resistance would be from the steak and connected to a water pipe
Dont connect to a water pipe, if there is a PEN fault, the water pipe could rise to 230V
On a totally non-electrical theme, been wondering why the picture shrinks in size in the last few seconds of the (past few months) videos
It's so the end screen overlay elements will fit without obscuring the video.
You are so epic -0-
WHEN CATS FART THEY STINK AWFULL BUT YOU CAN NEVER HEAR THEM DO IT
Something's bizarre. Why are we doing insulation resistance measurements in the Mohm range when L-E is 136 ohms ? It sounds like on this basis, E should be treated as live - in which case, it has no value !
i wish you could translate subtitled your videos in spanish, mr. ward. Congratulations
Just below far right of video is 3 dots in a row. Click on that for menu and choose 'open transcript'. Transcripts appears to right of video. Right click on the transcript and you might find an option to translate the page into .
2:17 you call it 25% increase, I think 19,5% is closer.
For me look so veryy dagerous,125ohms