Discuss No CPC on the lighting circuit but the customer wants a metal fitting!! in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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I agree. In a periodic no earth on a class 1 would be a C2 regardless of RCD etc. I don't think RCDs and lack of extraneous conductive parts is enough to make it a C3.

So you are right, you are still leaving a potentially dangerous fault. However I think there are a few mitigating reasons why this is acceptable.
First, as I see it, a certificate for a CU change is not certifying the complete installation. It is certifying the work done (i.e. the CU change) plus the circuits as they affect the operation. So Max Zs, IR, bonding etc is needed to ensure the CU works properly. A good example of this is from my last elecsa assessment. On testing I found a spur of a ring with a Zs of greater than 1.14ohms. if this was something I had just installed I would be failing the test and working out how to get the max Zs down. However as I was just changing the CU I determined it was due to poor design (read as mutiple ring extensions and long spurs done over the years), not bad connections, and noted on the cert that it was high but still within that required by the RCD protection.
In the same way, if I came across cables out of zones I would still do a CU change.

And, to be fair to the ESC, they are not saying that fitting an RCD is rectifying the problem. You still need to inform the client in writing that there is a potentially dangerous fault and also label the CU that there is no CPC in the circuit so only class 2 fittings can be used. All they are saying is that doesn't stop you doing a CU change.

That is the way I read it anyway ;)
 
I've had a look at the BPG, and to be honest I'm not happy with it.
It looks like they've altered some of it to allow class 1 fittings, but not considered how that impinges on the parts they have not altered.
Some of it appears contradictory, and some is misleading.
On page 3 they mention that prior to 1966, there was no requirement to provide a CPC for lighting circuits.
However they fail to mention that there would have been no exposed-conductive parts on such a circuit.
The fittings and accessories would have been plastic or bakelite, and either plastic inserts would have been provided in the back boxes to isolate metal screws, or plastic screws would have been used.
On page 4 they mention that there is no legal requirement to upgrade an existing installation to current standards.
Then on page 6 they state that a disclaimer does not absolve the installer from responsibility if the customer does not want their existing installation upgraded.
Again on page 3 they indicate that a CU does not have to be replaced to provide RCD protection for instances where RCD protection is now a requirement. They indicate that there are other methods to provide the required RCD protection.
However on page 7, they indicate that if a CU is replaced, then RCD protection must be provided.
So whist there is no legal requirement to upgrade an existing installation and because of this,we don't have to upgrade the lighting circuit.
It appears that we do have to upgrade the RCD protection even though it is already stated that there are other methods which don't involve incorporating the RCD in the CU.

There is mention that the Building Regulations require that any alteration or addition does not leave the installation any worse in compliance with Section 1 of the Building Regulations, they also mention the Scotish Regulations.
However they do not mention the requirement of BS7671 that an alteration or addition does not impair the safety of an existing installation.
I know that the BPGis quite a small document, but I find it odd that they have left out this particular piece of information, especially as they later suggest that a risk assesment is conducted.
I also find it odd, that the suggest refusing to carry out the work in certain circumstances, despite the fact that conducting the work would not make the installation any less compliant with Building regulations and would not impair the safety of the existing installation. It would in fact improve safety if we were to install a CU with incorporated RCD protection.

I could probably go on, but I can't be asked.
To my mind they updated version is worse than the previous version, and needs looking at again.
 
I agree! And I particularly find this bit annoying.....
I also find it odd, that the suggest refusing to carry out the work in certain circumstances, despite the fact that conducting the work would not make the installation any less compliant with Building regulations and would not impair the safety of the existing installation. It would in fact improve safety if we were to install a CU with incorporated RCD protection.

but at least if I follow guidelines from those that say they are experts in electrical safety then I have some small protection if things go wrong.....
 
We have a duty to not leave a site in a more dangerous state than before we started and in this respect installing a new dual RCD board or one with RCBO's will only make it safer. Plus adding bonding.

So if the lighting doesn't have a CPC and a couple of fittings are metal so what????????????????????
 
can you get a single earth back to the board and earth it like that or find the nearest earth and connect to that and label the board and note down on your cert ,there is to much relying on RCD's these days and they are not the be all and end all they do fail and often especially if no one tests them they can stick
 
can you get a single earth back to the board and earth it like that or find the nearest earth and connect to that and label the board and note down on your cert ,there is to much relying on RCD's these days and they are not the be all and end all they do fail and often especially if no one tests them they can stick

yes, had to replace a crabtree CU the other day as it was reported that "when I push the test button nothing happens. Been like that for years.....". Turns out the side of the RCD was melted and the RCD not operating. Still worked as an isolator though so I am not sure what happened to it. And that was on a TT system so no ADS on the installation for years. :(
 

Reply to No CPC on the lighting circuit but the customer wants a metal fitting!! in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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