Light switch earthing

[a1679]

As you, I am not an electrician...

Metal back boxes usually have a fixed lug (as well as an adjustable one), in which to screw the accessory into.
This fixed lug (and the screw connecting it) is sufficient to earth the back box (if the faceplate is metal, or the accessory is a socket).
The back box isn't required to be earthed independently, but it is considered good practice to run a flying lead between the two.

If the faceplate is plastic, the earth wires should be connected into the terminal on the metal back box (many plastic boxes also have a suitable terminal).

As opposed to what has been said above - I would run the primary earth wire to the place with the greatest risk, i.e. with a metal switch plate, I would run the earth to the switch plate itself, rather than having a flylead to the plate, from the back box.

Thank you. Is there definitive guidance on the back box not being required to be earthed independently? What in the case of a plastic faceplate?

 

[Jackrae]

Plastic face-plates still use steel or brass fixing screws so the argument about a loose wire contacting the unearthed back-box and hence making the fixing screws on the face-plate live still stands.

If you are concerned about the rest of the work they did, open up each switch plate and submit photographs for comment.

If what you have shown is anything to go by you'll have a case for getting your contractor back to do a proper job at their expense. If they are a registered electrician they are under a legal obligation to comply with standards. If they are non-registered then they will probably turn up on a horse.

 

[a1679]

Thanks to all for comments.

Have I understood the earthing requirements correctly?

Metal light switch - earth metal box and plate
Plastic light switch - earth metal box only

Metal socket - earth metal box and plate
Plastic socket - earth metal box and plate

If so, not sure how best to go about it.

Unfortunately most of the sockets and switches are caulked around as they weren’t flush to the wall, but looks like they’ll have to come off.

 

[RandomGrinch]

Thank you. Is there definitive guidance on the back box not being required to be earthed

This guidance is about as definite as I can find and from a pretty reliable source!

What in the case of a plastic faceplate?

If the (edit for clarity - switch) faceplate is plastic (and doesn't have an earth terminal), the earth wires should be connected into the terminal on the metal back box

 

[JohnW2]

Plastic face-plates still use steel or brass fixing screws so the argument about a loose wire contacting the unearthed back-box and hence making the fixing screws on the face-plate live still stands.

It does. However, whilst I cannot disagree with what you're saying (and many other people say), I think it represents a fairly deep scraping of the barrel of 'minute potential risks'.

How common do you think it is that someone comes in contact with a faceplate screw (the head of which is usually significantly recessed) at the very same time as touching something earthed - and however rare you think that would be, how commonly do you thing that it would not only happen, but happen at a time when a live wire was in contact with an unearthed backbox (itself a verey raree event).

However, I have to accept that people do (very occasionally) get struck by lightning (and that some may even have been hit by meteorites) - so I would not dismiss anything (other than 'everlasting life'!) as impossible

Kind Regards, John

 

[Sureitsoff?]

Thanks to all for comments.


Unfortunately most of the sockets and switches are caulked around as they weren’t flush to the wall, but looks like they’ll have to come off.

After that statement I would definetly take them off and check the wiring inside...

 

[Deryck Tintagel]

All back boxes and metal face-plates should be connected to the cpc but more importantly it appears that the 2-way Wago connectors each have three wires inserted. The wago connectors can only have 1 wire per point so you need to change the neutral wago to a 3-way version and the cpc one to a 4-way or 5-way version, the extra ways being to accommodate the back-box and face-pale tails. The fourth photo shows too much copper exposed on the live line

Not a spark but my two penn'orth ...

Personally, I would get rid of the Wago and connect the CPCs directly to the backbox - I don't see a need for a Wago here and kills two birds with one stone

 

[ebee]

Unfortunately most of the sockets and switches are caulked around as they weren’t flush to the wall, but looks like they’ll have to come off.

they weren’t flush to the wall . Blimey - Is this evidence of horsemanship ???

 

[ebee]

It does. However, whilst I cannot disagree with what you're saying (and many other people say), I think it represents a fairly deep scraping of the barrel of 'minute potential risks'.

I`m afraid I disagee there John,
It can happen that the switch retaining screw can become live, resulting in a tingle or even a shock of some magniude.
Earthing the backbox is one measure of mitigating this.


As an aside.

As for folk thinking a fixed lug is always accepatable as a connection between backbox and faceplate, I have stated my disagreement mainy times.

Actually I do admit that we never make much of a fuss about tablelamps BC lampholder being vacant an live possibility (I think we should - A few years back a young girl was electrocuted and I suspect that this might have been the cause). Even though safety disconnect lampholders are available the are never used.

 

[securespark]

Rarely, not never.

 

[a1679]

In the case of a light switch, what happens to the earth wires that are currently in the block? Do I move them elsewhere? Thank you

 

[RandomGrinch]

In the case of a light switch, what happens to the earth wires that are currently in the block? Do I move them elsewhere?

Is this now a plastic faceplate?

 

[a1679]

Is this now a plastic faceplate?

Yes, in the process of changing switches and sockets to plastic

 

[a1679]

As mentioned by @Jackrae there should only be one wire running into each port on those Wagos.

Feeding 4 cables in to a fitting designed for 2 is wrong on every level. I cannot see any justification for that.

An electrician has seen and advised multiple cables can go into the Wago. I’m perplexed!

 

[RandomGrinch]

Yes, in the process of changing switches and sockets to plastic

It looks as if the earth terminal may be under this snot of plaster - whether it has a screw in place is another story...