Is a borrowed earth allowed?

[a-z electrics]

Done an EICR yday on an old house and all ok apart from 2 issues..
1) 32A cooker circuit had high resistance pec continuity (over2kohms) ALTHO it did buzz out on my voltage probes. Hence not able to get a Zs reading and no rcd tripping. The dual rcd consumer unit was fitted 10 yrs ago and those test readings all available and fine. Kitchen was refitted 3 yrs ago and no docs available so they extended original cooker cable prob from the switch which is now tiled over somewhere.
.. I've put in an earth wire link from an immediately adjacent rfc socket into the cooker switch and this solves this problem.
Question .. is this ok as a permanent solution if i label up what ive done?
2) lowish IR readings 1.75M L-E and N-E on light circuits and one rfc but possibly in hindsight due to some bulbs, fan and appliances still plugged in. Could this account for it?

 

[buzzlightyear]

no this the answer rewire the circuit in full if possible .borrowing a earth from some where else .it will cause problems down the line if was a main fault .

 

[Pete999]

no this the answer rewire the circuit in full if possible .borrowing a earth from some where else .it will cause problems down the line if was a main fault .

Totaly agree with BL

 

[Midwest]

I'd say;
1) No, as each circuit must have its own cpc, as I recall.
2) Further investigation required

I don't do EICR's, but I recall you report, but not carry out the remedial work?

 

[freddo]

1 I wouldn't do it.

2 Could be anything, light bulbs shouldn't be causing L/N - E insulation faults!

Edit: Wow I was way too slow.

 

[a-z electrics]

no.borrowing a earth from some where else .it will cause problems down the line if was a main fault .

How do you mean "a main fault"?

 

[buzzlightyear]

How do you mean "a main fault

bang.

 

[a-z electrics]

I'd say;

I don't do EICR's, but I recall you report, but not carry out the remedial work?

I do if it removes immediate danger! Client not on site..

 

[buzzlightyear]

I do if it removes immediate danger! Client not on site..

try and explain to the HSE.

 

[westward10]

Anyone want to quote a Regulation where this is not permitted providing the borrowed cpc is adequate for fault protection requirements.

 

[Midwest]

I do if it removes immediate danger! Client not on site..

I'd just isolated the circuit, with clients permission of course.

You've not really done a permanent repair, and now your liable, should anything go wrong. If it was young family or someone frail, then as a temporary fix ok.

 

[Midwest]

Anyone want to quote a Regulation where this is not permitted providing the borrowed cpc is adequate for fault protection requirements.

No. I'll have a look. Might be some time.

 

[Pete999]

Anyone want to quote a Regulation where this is not permitted providing the borrowed cpc is adequate for fault protection requirements.

Not right now Westy, but go ahead fill yer boots

 

[westward10]

Not right now Westy, but go ahead fill yer boots

What I am saying is that he has done nothing wrong, it is permitted provided it is adequate for a cpc to serve more than one circuit. What he has done may seem unorthodox but I was asking for those who disagree with his actions to back it up with a Regulation.

 

[Leesparkykent]

There is no regulation that prohibits this.....What you’ve done is acceptable.

 

[Midwest]

I'm still looking.

 

[Pete999]

What I am saying is that he has done nothing wrong, it is permitted provided it is adequate for a cpc to serve more than one circuit. What he has done may seem unorthodox but I was asking for those who disagree with his actions to back it up with a Regulation.

Ah right, I don't have a copy of BS 7671, so in all honesty I can't confirm if there is a regulation.

 

[Kamikaze]

All long as he complies with regulations: 543.1.2, 543.1.3 and 543.1.4 then I can’t see nothing wrong with that.

 

[Wilko]

Anyone want to quote a Regulation where this is not permitted providing the borrowed cpc is adequate for fault protection requirements.

Question - what is the state of the cpc for the cable, along its length? Cables in walls 522.6.202 has me thinking about a screw being driven into the cable. If CPC is 2K then it should be sufficient to trip a 30mA RCD but the screw may exceed the 50V max target (1667 Ohms).

 

[Midwest]

Ok I give up, I'm orrffh to cook a curry is my excuse.

My thoughts were that the cpc must remain effective throughout the life of the install. Therefore, if the RFC is altered or removed subsequently, the installer altering/removing may not know the other circuit is reliant on its cpc.

 

[buzzlightyear]

What I am saying is that he has done nothing wrong, it is permitted provided it is adequate for a cpc to serve more than one circuit. What he has done may seem unorthodox but I was asking for those who disagree with his actions to back it up with a Regulation.

so Westy is like borrowing a neutral .

 

[buzzlightyear]

for the op .

 

[westward10]

Ok I give up, I'm orrffh to cook a curry is my excuse.

My thoughts were that the cpc must remain effective throughout the life of the install. Therefore, if the RFC is altered or removed subsequently, the installer altering/removing may not know the other circuit is reliant on its cpc.

You could argue if the problem cpc has only one break it is now effectively connected to earth from either end. I think it would be prudent to fit some form of info at the CU.

 

[Andy-1960]

I agree with Westy, the circuits cannot now be independently isolated, anyone working on the RFC in the future could potentially get a shock from the cooker circuit in the event of a fault on the cooker.
It is as BL says like borrowing a neutral, as soon as that link is disconnected there could be a potential difference between the two earth conductors.
Big problem with temporary repairs is that they have a nasty habit of become permanent repairs!
Also, what has now been done must surely screw the test results for the RFC, so how do you document that in the EICR?
Correct thing to do would be to isolate the cooker circuit and label it saying it is not to be used until remedial action has been carried out and document that to the client.

 

[Kamikaze]

2) lowish IR readings 1.75M L-E and N-E on light circuits and one rfc but possibly in hindsight due to some bulbs, fan and appliances still plugged in. Could this account for it?

If you got those readings of the same lighting circuit, then I would say there is a fault on that circuit. Did you disconnect the earth and neutral for that circuit out of the board before testing?

 

[Midwest]

I agree with Westy.

Think he disagrees with you?

 

[westward10]

Think he disagrees with you?

I didn't like to point out the error

 

[westward10]

so Westy is like borrowing a neutral .

Different scenario Buzz.

 

['mr2'gd4u]

Trouble is the diffence in size of cpc. 1.5mm on a 2.5mm ring (essentially 3mm) the cooker if in a 10mm t&e.. With a 4mm cpc... 6mm t&e is fine at 2.5mm cpc

 

[HappyHippyDad]

As some of the more experienced have said... It is fine to use a CPC common to two or more circuits, and it complies with a regulation 543.1.2 (as long as it's CSA is sufficient).

I do find it worrying when members, some are even trusted members, give the wrong advice and give it out so quickly without giving proper thought. We all get it wrong at times, but at least lets give it some thought before we get it wrong.

 

[buzzlightyear]

It is as BL says like borrowing a neutral, as soon as that link is disconnected there could be a potential difference between the two earth conductors.
Big problem with temporary repairs is that they have a nasty habit of become permanent repairs!

Different scenario Buzz.

how can it be a different . are you saying its ok to borrow a earth knowing if their is fault to earth It want clear quicker. IMO the op needs to ring his scam and get clarification.

 

[Midwest]

As some of the more experienced have said... It is fine to use a CPC common to two or more circuits, and it complies with a regulation 543.1.2 (as long as it's CSA is sufficient).

I do find it worrying when members, some are even trusted members, give the wrong advice and give it out so quickly without giving proper thought. We all get it wrong at times, but at least lets give it some thought before we get it wrong.

Thats told me then. Still think its so wrong though.

 

[Andy-1960]

I agree with Westy, the circuits cannot now be independently isolated, anyone working on the RFC in the future could potentially get a shock from the cooker circuit in the event of a fault on the cooker.
It is as BL says like borrowing a neutral, as soon as that link is disconnected there could be a potential difference between the two earth conductors.
Big problem with temporary repairs is that they have a nasty habit of become permanent repairs!
Also, what has now been done must surely screw the test results for the RFC, so how do you document that in the EICR?
Correct thing to do would be to isolate the cooker circuit and label it saying it is not to be used until remedial action has been carried out and document that to the client.

I agree with Westy.

I meant Midwest... sorry Westy!

 

[Midwest]

I meant Midwest... sorry Westy!

He needs to change his name. Something more befitting a Moderator.

 

[Andy-1960]

I agree with Westy.

I meant Midwest... sorry Westy!

 

[Midwest]

Who said that

 

[Deleted member 9648]

It is permitted for a protective conductor to be common to two or more circuits, I do not have the BBB to hand, only the BRB....where it is 543.1.2.
Edit...sorry, I see that's already been said.

 

[Nigel]

Nothing different than a conduit sytem being used as a cpc for multiple circuits.

 

[ruston]

I didn't like to point out the error

Not like you . Promotion has mellowed you.

 

[Midwest]

Nothing different than a conduit sytem being used as a cpc for multiple circuits.

But it ain't a conduit system, its in someone's house.

So so so wrong.

 

[Midwest]

Not like you . Promotion has mellowed you.

He is coming over a bit mellow at the moment. How long before his moustache slips?

 

[ruston]

When Elsparko comes back.

 

[buzzlightyear]

He is coming over a bit mellow at the moment. How long before his moustache slips?

YEAP .

 

[westward10]

I meant Midwest... sorry Westy!

He needs to change his name. Something more befitting a Moderator.

Open to suggestions providing it doesn't contain the word head and other body parts.

 

[DieselShunter]

I agree with Westy, the circuits cannot now be independently isolated, anyone working on the RFC in the future could potentially get a shock from the cooker circuit in the event of a fault on the cooker.
It is as BL says like borrowing a neutral, as soon as that link is disconnected there could be a potential difference between the two earth conductors.
Big problem with temporary repairs is that they have a nasty habit of become permanent repairs!
Also, what has now been done must surely screw the test results for the RFC, so how do you document that in the EICR?
Correct thing to do would be to isolate the cooker circuit and label it saying it is not to be used until remedial action has been carried out and document that to the client.

Borrowing a CPC is not the same as borrowing a Neutral. The Neutral is a live conductor whereas the CPC is not.

 

[Deleted member 9648]

Personally I would be reluctant to do it, but as far as I can see it complies. More of a concern is that the OP suggests the cooker circuit was extended during the kitchen refit and the joint appears hidden, if they didn't bother with the earth makes you wonder what the other connections are like.

 

[westward10]

Essentially the best course of action is to further investigate and if necessary rewire it.

 

[Wilko]

Hi - to me that circuit is proven to have a fault and the cause of the fault has not been found. There may be other faults or sections of the cable without CPC. CPC for 6mm is typically 2.5mm and the circuit has been returned to service with 1.5mm CPC from another circuit if I've understood correctly (?). I'm afraid this does not pass my sniff test for a fault free circuit, but I'm happy to learn .

 

[a-z electrics]

I'd just isolated the circuit, with clients permission of course.

You've not really done a permanent repair, and now your liable, should anything go wrong. If it was young family or someone frail, then as a temporary fix ok.

So you would have just left an unearthed cooker and microwave (also on the circuit) unearthed would you? Or say to the tenants you can't cook for 2 weeks? I have left it in a safer condition than it was. It is now effectively earthed.

 

[a-z electrics]

bang.

Better go bang than electrocuted..