no CPC on lights, - switches for class 2?

[1Justin]

I'm looking at the options for customer who has no CPC on lights as is quite common. I know the ESC "good practice guide" - and that all makes good sense.

However most light switches with exposed screws into metal back boxes (where metal box is unearthed because no CPC), would therefore be class 1. - I am looking here at a standard light switch directly outside the airing cupboard door (metal tank therein, touchy both maybe.. ).

Q) Might the ones with small plastic plugs (eg LAP 2-Gang 2-Way 10AX Light Switch White | NoLinkingToThis) be classified as Class 2 for the point of this exercise and be a suitable swap? They are not advertised as class 2, probably uncertified as that, but a safer bet than ones with exposed screw heads? (at least till someone looses the weeny button thingy) .

A related question. I guess BC lampholders are intrinsically class 1, but as they are right up there in the ceiling, what's the likelihood of Mrs Jones touching both the metal surround of her light holder (just as it fails L-E), and her radiator? If I assume normal length arms, I think we are safe here.. Where does one draw the line?

 

[Gazthesparky]

You must make sure the circuit is class 2 so light fittings and switches are plastic.

On the switch front then you can use either nylon pins to insulate between the metal back box and switch plate or using a switch that has plastic caps to cover the fixing pins

Then a label should be fitted to the consumer unit stating no metal fittings should be fitted and it should be noted on the electrical circtificate that this has been done and class 2 fittings fitted

 

[1Justin]

On the switch front then you can use either nylon pins to insulate between the metal back box and switch plate or using a switch that has plastic caps to cover the fixing pins

Hmmm.. Nylon pins? Do you mean fit nylon screws the same thread? Maplin maybe..?

The plates with the little plastic pips are more for the visuals than specifically for Class 2, so do I take it that using these is common where we have this issue?

 

[GLENNSPARK]

Hmmm.. Nylon pins? Do you mean fit nylon screws the same thread? Maplin maybe..?

The plates with the little plastic pips are more for the visuals than specifically for Class 2, so do I take it that using these is common where we have this issue?

just put the plastic caps over the screw heads...
job done...

 

[1Justin]

I'll get some of those in then..

I shall also chose to ignore all those switches with high IR (L+N..screw head), unless within reach of extaneous parts. This will probably be most of them I think, as long as they are away from radiators and pipes.

Would you change BC fittings for ES?

 

[GLENNSPARK]

I'll get some of those in then..

I shall also chose to ignore all those switches with high IR (L+N..screw head), unless within reach of extaneous parts. This will probably be most of them I think, as long as they are away from radiators and pipes.

Would you change BC fittings for ES?

no Justin...IR can break down...
get em covered ...like the others...
owt that could provide a potential here mate...

 

[GLENNSPARK]

I'll get some of those in then..

I shall also chose to ignore all those switches with high IR (L+N..screw head), unless within reach of extaneous parts. This will probably be most of them I think, as long as they are away from radiators and pipes.

Would you change BC fittings for ES?

whats the existing fittings....if any are metal and no CPC ...get em dropped...

 

[1Justin]

Well I should do so if that's the advice from the coal face.

The EIC best practice guide does say we can leave'em if > 1M Ohm..

BC fittings for ES: I am assuming BC has exposed metal surround which could become live if the L cable fell off internally and touched it. ES must normally be class 2 intrinsically, and I guess BC is class 1.

 

[Gazthesparky]

Hmmm.. Nylon pins? Do you mean fit nylon screws the same thread? Maplin maybe..?

The plates with the little plastic pips are more for the visuals than specifically for Class 2, so do I take it that using these is common where we have this issue?

Try these they insulate from the metal back box so no metal is showing and this means it is then class 2
http://uk.rs-online.com/mobile/p/machine-screws/0291414/

The switches with plastic caps comply with regs because it means that you Carnt touch the metal pins

 

[1Justin]

Try these they insulate from the metal back box so no metal is showing and this means it is then class 2
Buy Machine Screws Nylon 6.6 slot csk head screw,M3.5x16mm RS 6040424 online from RS for next day delivery.

Thanks. M3.5 eh? Nice one

 

[telectrix]

a lot of the back boxes may have nylon lugs if they've not been changed from the original. pendant BC lamp holders are classII.

 

[Mike66]

How can not earthing a metal back box be acceptable? Imo the best option is to remove the metal back box and replace it with a plastic surface box

 

[telectrix]

How can not earthing a metal back box be acceptable? Imo the best option is to remove the metal back box and replace it with a plastic surface box

if the above suggestions are followed, then it's perfectly acceptable. maybe not ideal but if the client won't pay for earthing to be added, nowt else you can do. and very few clients would accept ugly surface boxes. i know i wouldn't.

 

[Mike66]

So whats going to happen when screwing the switch plate back and the cable nicks the counter sunk screw and the metal box is not earthed. I do a lot of domestic testing and have done for many years. I have always classed this type of installation as unacceptable.

 

[telectrix]

it is unacceptable to install without earthing nowadays, but you can't condemn an older installation that was installed in accordance with the regs. at the time.

 

[Mike66]

I agree to a degree. Lighting circuits with no cpc are acceptable providing all fittings and accessories are class 2. I am a bit confused how covering a bare and exposed screw with a plasttic cap can be classed as a class 2 when the metal box behind it certainly is not
I had a customer recently who removed a surface box himself and fitted a flush box on a non earthed lighting circuit. I told him that it is wrong and he needed to change it to a surface box. He was not too happy about it but imo the customer should not dictate to you what you should accept as acceptable

 

[Gazthesparky]

The idea is that if there is a fault and the metal back box becomes live it. If a plastic switch with plastic caps covering the metal screws then its class 2 because you Carnt touch the metal

Using nylon screws does the same job it insulates the front switch plate from the back metal box

Yes technically the metal back box doesn't comply but due to the front switch plate being totally insulated its ok

 

[Mike66]

A bit dodgy when removing the switch for live testing though
On another note i was quite interested to see that the government are thinking of fast tracking ex forces into teachers. What a great idea it might just catch on. Now where have i seen that work before?

Funny but the NUT are not quite so supportive

 

[Mike66]

Hi all sorry forgot to say Hi on my first post

 

[Mike66]

Looking at the NICEIC snags & Solutions Part 1 Earthing Bonding & Snag 21 it states:

A metal back box for a surface mounted accessory such as a socket outlet is an exposed conductive part & a metal back box for a flush mounted socket outlet is deemed to be an exposed conductive part ( even though it may not be able to be touched ). Therfore, such back boxes, no les than every other exposed conductive part, are required to be earthed in accordance with Regulations 413-02-06 (TN systems) & 413-02-08 ( TT system )

 

[1Justin]

Looking at the NICEIC snags & Solutions Part 1 Earthing Bonding & Snag 21 it states:

A metal back box for a surface mounted accessory such as a socket outlet is an exposed conductive part & a metal back box for a flush mounted socket outlet is deemed to be an exposed conductive part ( even though it may not be able to be touched ). Therfore, such back boxes, no les than every other exposed conductive part, are required to be earthed in accordance with Regulations 413-02-06 (TN systems) & 413-02-08 ( TT system )

Thanks Mike, That's useful to know. But in that case, where is the pragmatic solution for those faced with no CPC and customers pockets too shallow to cope with a re-wire or boxes out? Many places will have render and/or rusted cut nails holding boxes in place. Replacing an old box is sometimes not trivial, and those difficult ones nearly always need plaster (or sometimes whole lumps of the wall..) touching up afterwards. I'm not looking for excuses, just solutions!

 

[telectrix]

the solution is in the esc guide....... as you say. cost and damage to decor are limiting factors on what you can or can't do. by ensuring that the back box has no chance of being touched and having class II fittings, with relevant documentation at the CU, that's sometimes all you can do. bear in mind that these installations have been installed for 50 years without electrocuting anyone.

 

[Mike66]

If I am carrying out a PIR inspection & came accross this type of install I would reccommend removal of the metal back box & fitting of a surface pattress IMO cost & disruption does not come into it.

We can only test to todays requirements & code any found departures accordingly.

Not so long ago it was ok to install an outside socket or install a shower without 30mA RCD protection, you wouldn't do it today.

You wouldn't install say a 28Watt 2D plastic light fitting with class 1 gear tray to a lighting cable with no CPC even though you cant touch the metal gear tray because it is enclosed in a class 2 fitting.

 

[Plonker 3]

No one is saying that is what you would install, what is being said is if it complied when it was installed then there is absolutely nothing to say it is wrong.

Yes it could be improved, but you can not force a issue just because you believe it is wrong.

 

[telectrix]

similar to all cars today are manufactured with seatbelts. you can't condemn a pre-1965 motor for not having them, though.