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 | Screwfix.com) 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?

 

[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.

 

[Plonker 3]

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

Always a good example this one.

 

[Mike66]

They dont go fast enough to warrant a seat belt, besides you have to get past that big steering wheel before you go through the windscreen LOL

 

[Guitarist]

I sometimes come across installs where the circuit itself has a cpc, but 3-core (not t&e) cabling has been dropped some switches for 2-way lighting with no cpc at the switch. Had a chat with Elecsa a while back about this, and it's quite acceptable to fit switches with plastic caps, along with a sticker on the backbox itself stating that no metal accessories are to be fitted. Not ideal, but a practical solution in many cases.

 

[7029 dave]

agreed with mike66, if the customer does not want the circuit rewired then go plastic surface boxes class2 job done.

 

[telectrix]

if i suggested surface mount to 90% of my customers, their 2nd word woud be OFF.