earth loop impedence values

[ericmark]

then the ELI is well within limits for TT (460 max).

It is actually 500 Ohms max. if you take Uo as 230v.

But either way with anything above 200 it must be ascertained that this is a stable reading and not likely to increase as ground conditions change.

To the op:-

I suggest you seek the services of a competant Electrician

The supply voltage doesn't make any difference, the calculation is on a maximum permissable touch voltage of 50v hence the max Zs for a 100mA RCD is 50v/0.1A=500 ohms
I'll 2nd the need to contact a competent electrician.

From the description he has a TN not a TT system. And only one socket tested likely it seems with one of these and the guy has a problem understanding what Zs and Ze is.

To get technical does not help him.

His options are either buy himself one of the cheap testers at £34.95 not too expensive and remove faulty sockets and physical test the earths. However these testers only test Zs and although one could make adaptors to test Ze with his admitted knowledge rather a dangerous idea. Also this does not give him the bit of paper he needs to help sell his house.

So it would seem his only option in real terms is to pay an electrician and since selling house he wants one with a scheme logo on his paper work to do a PIR (Periodic inspection Report) in the same way as he had the gas done. And at same time correct any minor faults. When I say minor I refer to amount of work not the amount of danger.

We know the lack of RCD's will be high lighted but if all faults are code 4 then that's all he needs to sell house. Even some code 2 faults my not be too bad but at the moment the fault highlighted is something that if I was buying the house I would want to know more.

In some ways when selling the house it would have been better not to have known. But now if someone should plug in a faulty bit of equipment into that socket and get electrocuted the investigation would show he was aware. So he must either rectify or pass on the information to the new occupiers.

I suppose he could be sneaky and state it is know the electrics don't comply with current regulations and a full PIR is recommended. I watched the political TV series last night. And that way he has said it is faulty without saying how bad it is. But I couldn't do that even if it did get me out of a hole.

So forget Ze, Zs, TN, TT lets try to give the man some advise he can use. To me that is still get some one in to do the work!

 

[Spark123]

Advice he can use:

Contact an electrician!!

 

[neilyboy1961]

update on previous problem gents, got gas board guy back with his meter and asked him to check socket again,same reading ,greater than 200 ohms,I then asked him to do the same test where the supply comes in,before the consumer unit and before the meter ,at the fuse albeit my side of the fuse.He got the same reading .

By eliminating my consumer unit and testing there does this prove that the fault is coming from the suppliers side ?

 

[skenk]

What tester was he testing with? What paperwork did you get? What did the 'gas board' tell you was wrong and what needed done about it?

Here's a tip - the 'Gas Board' (ie blood-sucking privately owned british gas) will rip you off at every turn. Just had a customer who was quoted £630 to replace a section of lead pipe by them

Without seeing the job we can't answer your question for certain.

You need an electrician, not a gas man with a tester who only seems to be able to tell you that something is wrong, and not tell you what you need to do about it.

 

[neilyboy1961]

didnt get name or make of it looked idiot proof ie connect leads here and press this button along the top 3 lights ,ok, not so ok and greater than 200 ohms.

only paperwork was a cert saying at risk installation.
Didnt tell me what was wrong he was a gas engineer just told me there is a fault

 

[RF Lighting]

Advice he can use:

Contact an electrician!!

 

[ban-all-sheds]

didnt get name or make of it looked idiot proof ie connect leads here and press this button along the top 3 lights ,ok, not so ok and greater than 200 ohms.

1) That's not a proper tester.

2) Think about what sort of person needs an idiot proof item of equipment.

Didnt tell me what was wrong

Because he doesn't know.

he was a gas engineer

And that's why.

just told me there is a fault

it seems a bit crazy to have a gas man inspect your electrical installation, would you want an electrician testing your gas install??

GET AN ELECTRICIAN.

 

[neilyboy1961]

to answer a previous question as to why the gas man was testing the electrics, he was visiting under their homecare scheme and said that the electrical check was to ensure the electrical work associated with the bolier was safe for him to work on.why he then went on to check further sockets I dont know.

Can anyone answer the previous question I posed.
If the impedence is tested at the supply side ie before the meter would that prove the fault is at the suppliers side ?

thanks

 

[ricicle]

The external impedance is normally tested after the meter by those not involved with DNO operations. This is more often than not at the incoming terminals to the installation main switch and involves turning off the switch and testing to the incoming earth which will be disconnected to avoid parallel paths.
This will then ascertain if the problem is external.

 

[neilyboy1961]

what are DNO operations ?

cheers

 

[securespark]

As I understand it from my last few gas visits from PB, the use of the SAS has now become widespread. They do it as a basic check to see if there is an acceptable earth connection to the property.

My gas eng. tested more than one socket on more than one circuit.

I think (to be fair to the gas eng who is only qualified to use the SAS) that if you get a bum result from more than one socket on more than one circuit, the ZE is bad.

FWIW, I think your "iron tube" carrying the live & neutral is not reliably connected to earth. Either that or the connection of your earthing conductor to that tube has gone west.

If I saw that set-up in a customer's property, I'd be calling the DNO to check it. If they don't like what they see, they'll upgrade it at their cost.

 

[stubob]

I had a customer with a similar problem. She had a new pump fitted to her central heating by BG. They did the S&See test and told her she had an earth problem and her life & property were at risk.

I checked & found the earth was relying on the a gas/water pipes, which was OK in the middle of the last century. However, as the external gas/water pipes are now probably plastic. they cannot now be relied on for adequate earthing.

I rang YEDL who are responsible for the supplies in the area, who stated that they are not legally obliged to supply earths to properties. They would however provide a PME connection for the cost of £153 + vat. This doesn't include any upgrading of the bonding or connecting the earth to the fusebox.

 

[JohnD]

I gather you do not want to get an electrician in for some reason

Do you, or anyone you know, have a digital camera; or a phone with camera that can be plugged into a PC? Otherwise, this long-distance diagnostics is mostly guesswork

 

[ricicle]

what are DNO operations ?

cheers

ie someone working for or on behalf of the 'electricity board'

DNO = Distribution Network Operator

 

[neilyboy1961]

Gents,
an update on my thread, supply providers agree reading is too high they were going to send someone today to check it but I'm off out to golf but they will come and see me tomorrow,will post results of test

thanks for everyones help so far