CPC/Earth feed to Light Switch Back Box

[BettyBoop44]

Hi
Just a bit of info required , just been checking all over the house checking for a earth feed to light fittings and switches , ( a friend informed yesterday that there friend have more or less sold there house , but an electrcal inspection has come up with no cpc to all the light switches ) .
I have found 3 light switch back boxes that do not have a earth feed to them , now the question is can I fit a plastic box inplace of the metal one that is in there and not need a earth feed to them ! .
All the light fittings have a earth feed to them ! , every circuit in the house is protected by a RCD .
cheers
BB

 

[Pete999]

Hi
Just a bit of info required , just been checking all over the house checking for a earth feed to light fittings and switches , ( a friend informed yesterday that there friend have more or less sold there house , but an electrcal inspection has come up with no cpc to all the light switches ) .
I have found 3 light switch back boxes that do not have a earth feed to them , now the question is can I fit a plastic box inplace of the metal one that is in there and not need a earth feed to them ! .
All the light fittings have a earth feed to them ! , every circuit in the house is protected by a RCD .
cheers
BB

Has the cable at the switch had cpc cut off where the cable enters the box?

 

[BettyBoop44]

Hi
Thanks for your reply , no there is no earth wire to the box ,only twin core cable .

cheers

BB

 

[Pete999]

Hi
Thanks for your reply , no there is no earth wire to the box ,only twin core cable .

cheers

BB

Not been snipped off where the outer sheathing finishes?

 

[BettyBoop44]

No just 2 core flat

 

[Pete999]

No just 2 core flat

So twin and earth from light to light with a twin to the switched, odd. Did the inspection produce any testing results? as it stands your friend can only use plstic switched, so no changing to fancy metallic switches.

 

[davesparks]

I've seen this as lot as it was quite common around here for the feeds to be wired in 3/029 twin&earth with the switch drops in twin 1/044.

The solution to this is to replace the switch drop cables with T&E after testing the circuit to confirm that the CPC present is viable and compliant.
But you should also consider that this is an old installation and there may be other things which require improvement. Adding a CPC to a few plastic switches is a bit pointless if the main earthing and bonding aren't up to scratch!

 

[davesparks]

So twin and earth from light to light with a twin to the switched, odd. .

Pretty common around here, I've fixed a few installations like this when I was doing domestics. Usually they have conduit down to the switches so it's an easy job to replace the switch drop with twin.
I think the reason it was done like this is that it was done when rewireing and the 3/029 twin didn't fit down the narrow conduits already in the wall.

 

[westward10]

Any chance of a pic for one of the back boxes.

 

[BettyBoop44]

So twin and earth from light to light with a twin to the switched, odd. Did the inspection produce any testing results? as it stands your friend can only use plstic switched, so no changing to fancy metallic switches.

Hi
Thanks for your reply , I am talking about my house not my friends friends house ! , the feed to the lights were also just 2 core flat , I fit a cpc to them a long time ago direct from the cpc bonding terminal next to the meter ,but did not think about the light switches , the kitchen and lounge light switches have a cpc they where put in when some workwas done there prob about 5 year ago .

cheers

BB

 

[BettyBoop44]

Hi
I really need a answer to my first post ie , can I fit a plastic back box in place of the metal one and then not need a cpc !

 

[LankyWill]

yes you could fit a plastic box in leui of a metal one, but remember the accessory would also have to be plastic. Are they cpc's at the light fittings?

 

[BettyBoop44]

Hi
Thanks for your reply , can you please read my #10 post .

cheers

 

[Pat H]

If the back box and light switch are both non metallic then no CPC is required.
However care must be taken that a later owner doesn't add metal faced switches and a risk is created. We don't rely on RCD for protection as they can fail.
You could leave a note in the plastic backbox as a reminder that no CPC is present and no metal switches to be installed as a sort of gift to the next owner.

 

[westward10]

Hi
I really need a answer to my first post ie , can I fit a plastic back box in place of the metal one and then not need a cpc !

I assume these are flush to the wall boxes and plastic isn't ideal for this. Do the existing boxes have plastic lugs for the cover screws.