wierd rfc problem

[soulman]

While doing a EICR with another electrician today, we come across something quite strange on both of the rings firstly within the consumer unit for both rings there were two lines & two neutrals for each ring as there should be but only one cpc per ring, we tried to pull the cables through from the back of the consumer but couldn't as they were trapped within the wall. so went to a socket outlet to try and obtain end to end continuity on the cpc . we got correct readings on the down ring but open circuit on the upstairs ring. we then took a zs reading at each socket outlet and readings were good. The electrician i was working with passed the installation as satisfactory as there was an earth at each socket outlet. He coded the two circuits C3 and marked requires further investigation.

What i want to know is this correct should this installation have passed.

Cheers

 

[GLENNSPARK]

well i reckon it it requires improvement as the CPC isn`t a true ring...is it....so i would have given it a (2)...requires improvement....

 

[soulman]

so would you have failed the installation glenspark. I would have thought c2, but the spark i was with said it wasn't and he has been in the industry for many. i just thought the danger would be down to the sizing of cpc as it should be 3.0mm and not 1.5mm as the ring is 2.5 + 2.5 =5 or am i off the ball here. He also said that the cable will not be overloaded as the line & neutral are in a ring and there is a cpc at each socket outlet so how can u fail it. Who am i to question him.

Cheers

 

[londonlec]

No continuity on ring circuit is a C2 for me

 

[Yooj]

C2, and requires further investigation. I would have been inclined to isolate everything, disconnect bonding and do a wander lead check at each outlet on the ring to see where the problem was, as you may well of got your Zs readings via bonding/supplementary bonding.

Yooj

 

[soulman]

yooj wander lead method was used before everything to check for an earth at every outlet. test showed o.k
Cheers for the responses i knew i was right.

 

[Yooj]

yooj wander lead method was used before everything to check for an earth at every outlet. test showed o.k
....

But was the main bonding disconnected at the board when you did the wander lead, as this could have given the return path if it was not disconnected.

If it was disconnected, then it looks like the CPC is broken between the last accessory and the board.

Yooj

 

[TaffyDuck]

C2 without a doubt in my book, one of the required tests for a RFC is continuity of CPC, if there isnt a r2 then it isnt a ring irrespective of whether Zs is adequate.

 

[drew35]

A ring final circuit having a discontinuous conductor, code 2 best practise guide.

Cross-sectional area of the earthing conductor does not satisfy the adiabatic requirements (543.1.1) Code 2 best practise guide. Not sure about this one, you do the math!

Unsatisfactory.

 

[drew35]

Also what about the box on the certificate, continuity of ring final circuit? Just tick it??? You can't put an X or its a fail anyway isn't it?

And the box on the test page, end to end R2???

 

[i=p/u]

1mm earth would be fine according to adiabatic equation. but i would say it is unsatisfactory as you couldn't fill in two boxes within eicr...

 

[Yooj]

... Cross-sectional area of the earthing conductor does not satisfy the adiabatic requirements (543.1.1) Code 2 best practise guide. Not sure about this one, you do the math!...

I did think about this, and concluded that the worst case scenario for L-E fault current is the fault being closest to the consumer unit, and thus if it does not satisfy the adiabatic now, it probably would not have done so before the CPC was broken...

Yooj

 

[soulman]

Thank you, for the excellent response as usual, much appreciated, i've printed your replies and i'll give them to him, believe it not i was watching him to gain a little more experience. As he has been inspecting & testing for twenty years maybe he needs a refresher.

 

[Yooj]

Just be careful that you don't go and put his nose out of joint over this one thing... I don't know what this other guys capabilities are, but don't discount him just because of this one thing. Additionally, it's his signature and not yours at the bottom of the EICR (I am assuming anyway), and any come back is on him and not you... So if I were you, I would not be crusading about it, and just put it down to experience, and be happy that your spider-sense was tingling, and you have had your thoughts confirmed.

Yooj

 

[rich.250]

believe it not i was watching him to gain a little more experience. As he has been inspecting & testing for twenty years maybe he needs a refresher.[/QUOTE]

This doesn't mean he is right.....
I've seen people who have been testing for years, and don't have a clue. Just read the screen. LOL
I too would C2 it.
It scares me, some people will pass anything!!
Ignorance is bliss as they say lol