Earth Electrode Testing
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- เผยแพร่เมื่อ 26 ก.ย. 2024
- Overview of different methods of testing earth electrodes to ensure their impedance is low enough.
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I am building my home in Thailand, realising early on that there is no electrical standard and very little knowledge of Earthing, I decided to use an UFER grounding system. All my rebar is connected together, by welding and thick copper/brass cable joints, then concrete is poured and metal points at 4 corners of each building come out and all the risers and are connected above the floor plane to a common point by copper cables, all dry, sheltered and protected. For anti corrosion I smuggled in a tin of Copperease (can't get that here along with Marmite and PG Tips) as we used to use that on ships' antennae installations, it doesn't wash off or emollify much. I use a Three Terminal Ying Tong Meter as above and thank you for your video as when I got it the bloody thing the destructions were all in Chinese. For the whole installation therefore I use multiple earths for each supply box being the UFER grounds, as the company supply earth isn't available (LN only) and anyway it's just a piece of galvanised metal buried in dry sand. Drinks are on me if you are ever in Hua Hin area.
Thank you for taking the time to make all these great videos and educate the rest of us. Best of luck to you and your family in 2017!!!
Just to say I really enjoy your videos, the style in which they are presented and that I appreciate the amount of time you must spend in doing these. Thank you.
Great video, though you could have mentioned that the middle electrode (commonly designated as S) is just a high impedance voltage measuring probe, while the outer probes (commonly designated as E (earth) and H(auxiliary)) are used to inject AC current into the soil. Resistance is calculated internally as the voltage measured at the S-probe divided by the current measured internally by the instrument itself.
As always very clearly explained.
Thank you for your time to teach. You make understanding simple. Thank you Sir!
Another excellent, well explained video.Cheers John.And Happy New Year
Surely the resistance will vary greatly at the same installation depending on the type of soil and for a given soil type, its wetness or dryness. Presumably the test should be done after a (long) dry spell.
Thank you so much sir for your rich information and simple gorgeous way in explaining the lecture, appreciate your help and effort making the information so simple and approachable, from kuwait ali
Thanks A lot John! very clear and the explanation is straight to the point !
Thanks John. You mentioned that you might be doing these tests while it is raining. Is it necessary to repeat the test when the ground is drier to ensure that the resistance will still be low enough during hot periods with little rain, or does it not change much?
Ideally you want to do it when the conditions are least favourable, say a hot dry day
I like your videos because I like to see the differences from here in the US . We should all use the term earthing like you guys do . We just say grounding wire and some times there is confusion between it and the neutral , and as you know we split our 240 to 120 circuts so a neutral go with every 120 circut. This was deliberately set up by Elihu Thomson for safety?
Im wondering which direction you would go away from the original earth stake. If i had a new overhead pole put in for my new supply (I'm very out in the sticks) would I be advised to head towards the pole which happens to be in the same direction of an overhead transformer for me and a neighbour on the next farm.
The new supply is PME but the estimator guy said to put an earth stake in with a 25mm CPC connection to it. Never had that request before in my youger days of new house etc.
Doesn't matter particularly, other than it should not be near any other buried metalwork, cables, pipes or other electrodes. 10 metres distance from anything else at least.
(Newbie) So what’s the score on wet ground? If you do the tests/install in a soggy February and you get good reading and we have a very dry summer and the ground drys out. Cheers enjoy the vids.
This is deeper knowledge. We greatful
Damn!! here in the US we have to use 10 foot (3m) rods and achieve 3 to 6 ohms of resistance. I've also had to use 1/4" x 12" X 12" copper plate or ufer grounds for the hard to get places.
Because of the 110V mains
why resistance decreases by increasing the distance between the two rod?
Hey John hope you can help me with the question it reads: A maximum earth resistance of 300 Ω, shall be maintained between electric fence earth
electrodes. Do I connect the leads to both electrodes +- 30meters away. Or do I insert the small electrodes into the ground as shown on your video the electrodes are 1.2meter long.
hey john! great video. i realyl like the quality of your videos. what kind of camera do you use?
Thanks for the vid...
Have a good new year!
Cheers
I am trying to find the video for the first method of earth testing when power is available, cannot find it ?
Need more details regarding how exactly this mechanism works
How to measure the resistance of the grid ? I believe the grid resistance will affect the earth resistance. Please correct me if I'm wrong
good explanation John.
Thank you for this video sir.it's my first time working in earthing and im looking for some info.and im found yours.thanks.
Hi this is great because it gives me ideas of how to achieve my goal, but I would like to know more about the meter you’re using I have been told I need to use a mega but this looks like something else you have but you did not mention what it was. I use Radio and I need to know I have a resistance of less than 10 ohms. This sends current, and I am afraid to test as I may damage my equipment. 🤔. This demonstration 👍 just need to know more.
Do you have a reference for the easy method on your videos? I can't find the link despite searching. Thanks.
I find it always best to use a 17th or 18th edition multi function tester to measure the Ra or earth fault loop impedance for the means of earthing. The three spike testers will not measure the critical loop to ensure automatic operation of the RCD's. They can be misunderstood and also show incorrect readings from the short temporary spikes into dryer topsoil rather than deep clay,
Two wire testers will measure the entire earth fault path from the transformer through the line conductor, down the spike to the ground, and across the ground and back to the high voltage earth at the TX. this needs to be below 200 ohms and is the best method by far.
You also need to ensure that you disconnect the earthing conductor and test only the means of earthing (NOT parallel paths to heating systems and water mains etc.) You MUST also ensure that this test is done with ALL current using equipment turned off at the main switch to ensure nobody can become injured while the earth has been disconnected.
@David Morris Exactly David, that three wire test method is a nonsense and only tests the ground between the three electrodes used and not the critical Ze (Ra) measurement. Don’t waste your time attempting it mate.
Thank you for your video. Very informative and helpful.
I could not find your video about measuring earth resistance when the main electricity is available, and ask my question here
Can one get results using any household electric appliance like, say, Incandescent light bulb, a mulimeter and the old good Ohm's Law?
One terminal of the bulb is connected to live, the other to earth and the current is measured. Divide voltage by current and subtruct the bulb's resistance and the result is the earth resistance.
In theory that could work. In reality you do NOT want to be attempting that, as doing so will put a significant voltage onto the electrode and anything else connected to it which could be dangerous. Would also need a circuit with no RCD on it, otherwise it would trip immediately.
Other videos are here:
th-cam.com/video/_BkN8fRLYXw/w-d-xo.html
th-cam.com/video/K0P5wGSjxLE/w-d-xo.html
all others can be searched from the main channel page.
@@jwflame Thank you for answering. If I got you correctly, this method will give sufficiently valid result, yet it is not safe. I still cannot understand the danger. Significant voltage is the same 240 (in my place it is 220) - and this is a voltage we handle habitually with common sense. I am going to use an electric plug and a lamp socket. Connect the live pole of the plug to one lamp socket terminal (the other plug pole unused). The other lamp pole terminal connect to the earth. Of course making all these connections while the main switch is off.
RCD is already there
Dear Sir
I'm working on an existing hospital over 30 yrs old, and i found only lightening pits connected to the lightening grid on roof, how should I test the earthing system and is it possible for the designer to used the concrete grid instead of the earthing electrode ?
How can you test an earth electrode if you can not find it because it's Hiden under a deck or something please ?
Nice course i appretiate it good explaination but thats not enough for me you suppose to talk about the soil type as well and the great ground résistance value for in low voltage and Médium voltage
Here in denmark, we rely on rcd's for protection. They are in fact required by law to be installed in all consumer units. Therefore, the earth electrode needs to fit the rcd. As 50 volts is max alowed for humans to touch and most rcd's trip at 0,03 amps, the max resistans for the earthrod is 50/0,03 = 1666 ohms. Some equipment require 0,1 or 0,3 amp rcd's so 500 and 166 ohms. Could you please explain why you say 100 ohms for TT in england? And thank you for all the videos you do, I realy enjoy watching them. As others has said before, you can explain things so everyone can understand them. Keep them comming 🙂
According to the On-Site Guide (BS 7671) it's between 21 and 200 ohms on a TT Earthing System. Obviously the closer you get to 21 ohms the better.
Calculation is misguided. There's a potential divider effect. Faulty low rsistance load connected to high resistance earth rod gives a high voltage on the supposed 'earth' wire.
You done a great job thank you so much. Very useful for me.
Some people ,knowingly or unknowingly, put common salt ,charcoal inside the pit(dug for the purpose), before putting a GI pipe (though costly). Will the salt help significantly or is it only a precaution?
It will reduce the impedance, but it will also increase corrosion so is not recommended.
How we could test it if the main power available ?
Wet your fingers and touch the mains cables
Really informative videos. Be great to have one on hot tub installations as there's a lot of conflicting information around interpretation of BS7671 special locations, PME, TT systems etc. I'm sure you could guide people through the correct best practice, and I for one would appreciate some expert clarification.
thanks a lot for your recommendation and knowledge
Very informative, thanks!
What's the purpose of moving the earth spikes please?
What do you do when you have the earth rod to test surrounded by concrete slab, where do you put the test probes with the spikes? Thanks for the vid 🤗
If it's all concrete then you can't- however other test methods are available.
@@jwflame I was thinking to try a Ze test.
If u use a earth grid or earth tape how far do they need to be in the earth?
Wonderful.. So helpful, thanks John
When doing the 'rod test', all very well testing your own electrode, but what about the impedance of the earth-electrode at the source transformer, how do you test that // what standards is 'their' elecrode rated/checked to?
It should be less than 21 ohms, usually a lot less. The earth electrode at the transformer is usually a large metal grid buried in the ground, not a single rod.
DNO's sometimes spend more money getting a low enough earth impedance at the substation than the cost of the substation, TN-C-S is therefore more or less guaranteed to be good!
Test again with mains, and compare the two?, Line conductor impedance should add rather little to the loop
So how do you do this without special testers? Seems like you could
Well, Can you Clarify my few doubts Sir.
1. What is the reason behind puting the 10 time of Depth of Earth road.
If not maintained what will happen
Than it's in the same area ...
Great video very helpful
9:00 - Words spoken by someone who's obviously done this themselves ;-)
That sun looking cool
so if we have well of earth 40m and electrode of 3m distance of t1 400 m
Dear Mr.John ,
I have to test the earthing for 40 connected electrodes (earthing network ) .
Please tell me if I can use 62 % way , and please tell me if i have to isolate the electrode from the earhting network during this test ?
Best Regards,
You can test the electrodes together, but they must be disconnected from the electrical installation when testing.
good vid, but slightly confused, putting aside the 10:1 rule surely connecting multiple rods to a soil with poor conductivity even if they are inches apart will gain more surface area, hence better figures. Im guessing that surface area plays a big role here
Surface area is the main factor, so more is certainly better.
Multiple rods close together will be better than a single rod, but spacing them apart is better still - and as the effort of installation is the same regardless of where they are located, they may as well be spaced apart.
@@jwflame thanks JW, its an awkward question I know!
@@jwflame I guess that if theres no option due to area restriction and crappy soil condition, planting them very close and bonding together is the second best thing as we dont want voltage potential
Correct me if possible, but i thought the ideal Earth test resistance should be less than 1 Ohm?
Less than 1 ohm on TN systems where the earth is provided from a cable.
With an earth electrode (TT), resistance will be much higher as it depends on the resistance of the electrode to the surrounding soil, which is typically many 10s of ohms.
It should be noted TT earth impedance can easily double from wet months to dry months throughout the year, I guess that why
For real , thank you sir
Thank you so much!
I used to do this with a variation of a whetstone bridge
I am unclear why the electrodes need to be far apart yet tape or a grid or a pipe are considered the same thing. They are not only Not Far Apart but continuous?
Given two electrodes, spacing them apart gives more 'bang for the buck' than putting them close together, tape/grid would just overwhelm that with shear area.
I.e. where two electrodes far apart might have half the resistance, close together would have more than half
What madman dislikes earth electrode testing???
Pass the hi Vis vest and boots. We playing in the mud! Another classic JW crystal clear explanation
All Thai "electricians" who are also "car mechanics", "builders" "architects" "pilots" etc etc
The type that wants to be an earth electrode
where can I find the previous video or how is its filename so that I can watch it ?
All videos here, arranged by topic: th-cam.com/users/jjwardplaylists?shelf_id=0&view=1&sort=dd
thanks a lot sir
Thankyou sir
Wrong middle lead is 62% of long leads distance
Somebody is awake early!
so you do not want anyone else to learn
Thsnks
He's wearing a Stewie T-Shirt. This is commendable !
Good.
Hi John,
do you any video showing the use of method 1, i.e. mains?
Not yet. Hopefully will do videos showing all of the various tests, but it is rather difficult to find somewhere that it's possible to show the tests, and get permission of the building owner. Making a video while doing them means it will take several times longer, so a few hours of tests could end up taking a couple of days - most people don't want that.
Hi John do you have video showing testing when mains available ? Or can u explain in writing ?
I like and Englihs and spanish type bilingue okey...!
What do you do for earthing the elctrode if you live on a old lava field and have no soil besides solid lava rock?
Question: Can a person who has ZERO ground in a house, ground just ONE power outlet in the house by running a ground wire from the ground terminal out into a grounded stake in the ground? My house has old screw in fuses, and absolutely no ground wire anywhere. There's no plumbing or anything in the house to use for a ground either. I run a compost toilet/outhouse, and haul water there. I want to avoid the risk of frying my electronics but I cannot afford a full electrical update. It's 10,000-12,000 to do this (almost as much as I PAID for the house!!)... I won't be able to afford it for YEARS best case. SO what I want to do, is somehow protect my electronics by at least grounding ONE outlet cheaply. Is this possible? AND NO, I DO NOT HAVE INSURANCE, so I don't care if things are certified insurable, just so long as my gear is safe.
229 dislikes. Arrest former CEO Susan for protecting corporations.
is there not a risk of striking a buried cable or pipe when driving these electrodes in?
Yes, so a proper survey is essential before installing one.
Ben Harris Oh yes there is a friend of mine who is a spark was driving a spike in and hit a Gas pipe ? Gas company had to dig up a drive needless to say the owner was none to happy?
V nice sir good explain
Dear sir, is the type of material of the electrode important and affecting the readings significantly?
No, as long as it is conductive. The main thing affecting resistance/impedance is the contact between the electrode and the surrounding soil. Longer rods or larger diameter rods will improve this as there is more surface area.
John Ward Dear Sir, many thanks for your kind reply. I was considering the options of electrode, as the high copper content composition one costs 4x more than the generic ones.
Thank you. And i love your channel!
Super
Stewie Griffin 😂 1st thing I noticed when video started.
Thanks for sharing another great video. 👍
Is this what is called 'Ra' testing?
Yes, Rₐ is the resistance of the earth electrode and the conductor connected to it.
John Ward thanks John, having a nightmare trying to get a suitable Earth, presently cannot get below 1.8k with three earth rods, now going to try tape on Monday once Yesss opens up..
I have concrete ground 😢
Good
Did I hear you right , earthing electrodes are not required on new installations .
Yes, but only because new installations are very unlikely to be TT.
If a new install is TT, then an electrode is required.
What is TT?But in the Netherlands,every dwelling,every family home,every housing flat has to have its own earth pin!If the Housing flat is long even more than one!It amazes me to hear this is not required in the UK for new installations.
Computer Addic We usually use the suppliers earth. the most common earthing method in the UK is known as TN-CS. essentially all line to earth fault are converted into line neutral faults. The earth electrode (or earth pin as you call it) is generally only used in rural areas.
So the resistance to earth is higher than in the Netherlands.We think 10 ohms is a lot!
TT is where the only earth connection is via the electrode, the electricity supplier does not provide any earth connection from their cable. Most supplies in the UK have the earth connection provided as part of the supplier's cable and a separate electrode is not required.
Quiero que se explique en español por favor..
Why do we do this test ?
To ensure the impedance is low enough to trip the protective device (an RCD usually) when a fault occurs.
If it was too high, a fault between line and earth in the installation would result in exposed metalwork becoming live, and the power would not be disconnected.
Thanks a lot great explanation
كيفيت حساب
Save the environment by writing on both sides of the paper or use a tablet!
Stewie!
in hindi
ka hindi ma na bol sakte hai Na ki
bare mumble
Horrid explanation JW! This is the worst training on earth electrode testing that I’ve possibly ever seen! If you don’t know what you’re talking about, why would you sit there and muddle your way through it and tell people some stupid stories!
I like your videos and for any one that likes the history of this topic a great person to look up is Elihu Thomson.
What shall be the earth electrode resistance
Depends on the circumstances and the installation, but generally less than 200 ohms is required, and lower is better.
Very useful, thanks very much for also adding the what if section, really helpful.
Fantastic video. Thanks for making it look easy to understand
What is the angle between other two electrodes
I think it has to be in the same line
After getting resistance of electrode , how to get soil resistivity