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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thwaitpd

Hi i have been approached by a customer who wants a metal light fitting (obvious needs a cpc) but the wiring is from the 60s and they only installed twin L+N. If i run a CPC from a socket in the room up to the light fitting is this acceptable?
 
The cpc should follow the route of the cable for which the cpc applies and would need to be 4mm if unprotected.
Best to run a cpc from the CU along the circuit to the fitting (and cover the light switch as well!)
 
as above^^^ or you don't do the job.
 
Don't forget 30mA protection and Boding etc lol

What a load of effort for a bloomin light fitting... Soon see how much they like it when they look over your quote;)
 
Hi i have been approached by a customer who wants a metal light fitting (obvious needs a cpc) but the wiring is from the 60s and they only installed twin L+N. If i run a CPC from a socket in the room up to the light fitting is this acceptable?

The problem with doing it the way you have suggested, there is no R1 & R2 from the DB's lighting circuit to that metal fitting ( although it is earthed from the sockets). Best to run a seperate cpc or get a different fitting as others have said.
 
So is that document saying that you can fit class 1 fittings without a CPc asking as an ir value over 1Mohm is achieved? And an RCd is fitted !!!
 
Ok so say you do a cu change then are they saying that you can leave the class1 fittings fitted!!
 
only if the fitting is not simultaneously accessible with earthed metal parts. personally , i would not like to use that argument in front of a judge and jury.
 
only if the fitting is not simultaneously accessible with earthed metal parts. personally , i would not like to use that argument in front of a judge and jury.

No neither would I but I am trying to find a way to justify it in my head but I just can't seem to be able to!
 
No neither would I but I am trying to find a way to justify it in my head but I just can't seem to be able to!

There isn't any real justification of allowing Class1 lighting fittings on a Class11 circuit. This is just another cover all situation where an RCD is being used to replace a non-existent ADS. Seems even the powers at be, can so easily forget that RCD devices are supposed to be ''Additional'' Protection, and not a Primary protection on TN installations!!!
 
Has the ECS guidance changed?
It always used to be that the departure was to install a 30mA RCD, Class II fittings, and a notice at the CU warning about the lack of CPC and not to install Class I fittings and accessories.
 
Sorry to resurrect an old thread but I am curious about some of the comments here on the ESC guide.
I think the guide makes it clear that all class 1 fittings should have a cpc. BUT, if there isn't a cpc and the customer refuses a rewire or change of fitting what do you do?

The way I read it the guide is saying "do your best to reduce the risk as much as possible". ie. do your risk assessment and except that zero risk is not going to achievable!
So,
1) If there are simultaneous conductive parts accessible then it really is too high a risk, even with an RCD. (RCD being additional protection....). Therefore don't do the job.
2) If there are no simultaneous conductive parts, ie. a low risk of a good earth path then relying on an RCD is an acceptable reduction in risk from the current situation (i.e. not RCD) so do the CU change.

As already pointed out this is not relevent to adding a class 1 fitting to a circuit with no cpc. That is clearly increasing the risk and not acceptable.

Last comment. It has been stated that the cpc must follow the path of the L/N in this situation of fitting a class 1 accessory to an existing circuit. What reg (or logic) requires this?
Again, my logic is that the CPC is being supplied purely to protect the class 1 accessory. Not the circuit supplying it! So as long as there is a reliable earth at the accessory (however achieved) it is acceptable.
Obviously, if installing the circuit from scratch I would need the cpc to follow the L/N to protect the circuit (along with RCDs etc as necessary) but this is a different situation.

Anyone care to give the counter argument?
 
The advice given by the ESC (unless it has changed to allow class 1 fittings), is a departure which would provide the same degree of safety as would be provided by compliance with the Regulations.
Care would have to be taken to ensure that there are no exposed-conductive parts, metal fitings, metal accessories or even metal accessory screw heads.
To my mind the fact that there are no exposed or extraneous-conductive parts within reach of an exposed-conductive part of a lighting circuit is not enough.
An earth path can be provided through walls, floors and ceilings.

I agree that there is no requirement for the earthing conductor to follow the L & N of the circuit, the conductor would not be considered as being a circuit conductor (CPC), as it would only be earthing the exposed-conductive part.
 
Thanks spinlondon.
The advice in the current best practice guide 1 is that you can change a CU if there is a class 1 fitting without a cpc or earth, as long as there is no exposed or extraneous conductive part within reach - as long as the cct has an RCD fitting. Is this a change from previously?
Assuming this is an change to the advice it is clear it does not afford the same level of safety as the regs but it is certainly better protected than a (pre CU change) installation with no cpc, class 1 fittings and no RCDs. So I guess what they are saying is that the addition of the RCDs is a worthwhile improvement, even if it doesn't meet the intent of the regs.
 
Obviously things change.
The ESC/NICEIC have taken the view, that if the metal fitting/s is/are existing, then changing the CU will not impair the safety of the installation, and that by providing RCD protection, safety will be improved.
The problem I have, is how this relates to the Regulations.
Whilst you are not required to update an existing installation, if it complied with the Regulations current at the time of design/construction.
I'm not aware that an unearthed exposed-conductive part has ever complied, certainly not within the last 46 years.
As such I would consider such a situation to warrent a code C2 if I were to conduct a Periodic Inspection.
To my mind providing RCD protection in such circumstances would not rectify the non compliance.
It may reduce the danger, so that a code C3 would be applicable, but would not remove it altogether, it would not comply with the current Regulations and would not be considered (to my mind) as an acceptable 'departure'.

This then poses problems when it comes to certification of the work.
Regulation 632.4 requires: "Defects or omissions revealed during inspection and testing of the installation work covered by the Certificate shall be made good before the Certificate is issued".
Whilst there is no requirement for you to upgrade the existing installation (if it complied at the time of design/construction) and it would be acceptable to note the defect/non-compliance under 'comments on the existing installation'.
If the installation of the RCD is intended to rectify the defect/non-compliance, it would fail inital verification, as the measure would not still not comply, and would not be acceptable as a departure becuse it does not afford the same degree of safety as would be achieved by compliance with the Regulations.

Then of course you have the fact, that by allowing such a situation to be rectified by the provision of RCD protection, you are effectively allowing any or all of the fittings and accessories to be changed to class 1.

I wonder what next the ESC/NICEIC will allow.
Cables concealed in walls outside of prescribed zones, as long as they are protected by RCDs?
Perhaps exposed live conductors, as long as they are protected by RCDs?
 

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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