Replacing existing Ring Main Sockets with Metal Ones

[drewks]

Hi there y'all
I'm replacing very tired plastic 2 gang switched sockets in the kitchen with smart brushed metal ones.......the existing sockets are mounted on plastic dry lining boxes. Is this OK - I'm thinking with a metal socket I'd have to earth each one to the box (if metal). Do I therefore need to replace the existing boxes with metal ones in order to do this??
Thanks VERY much!

 

[Chivers7]

The existing earth on the twin and earth should suffice in providing an Earth to the sockets. No need to change the boxes but if you do and swap for metal then these will need earthing along with the sockets so the screws are earthed and do not become dangerous under fault conditions. Since the current boxes are plastic you're ok to replace "like for like"

 

[Chri5]

Just watch out for depth issues, the flat faced sockets have a deeper inner and on shallow back boxes this can cause issue with closing the socket fitting.

 

[Taylortwocities]

Most plasterboard (plastic) boxes are 35mm deep & OK for most sockets, even the flat ones..

TTC

 

[festa]

Here`s one for you if you.........

If you just connected the CPC from the twin and earth straight to the back of the metal face plate.....would you really think you would need to attach a flying CPC from the faceplate to a metal backbox?

 

[Spark123]

I'd do it just for consistency, but the official take seems to be if there is a fixed lug on a sunk metal back box then the link isn't necessary.
Not to forget, plastic sockets are constructed as to earth the fixing screws too.

 

[bernardgreen]

I'd do it just for consistency, but the official take seems to be if there is a fixed lug on a sunk metal back box then the link isn't necessary.
Not to forget, plastic sockets are constructed as to earth the fixing screws too.

Since some metal face plates now come with gold coloured plastic ( or nylon ) screws it could be the back box remains without an earth and thus could be live if insulation is damaged.

 

[Taylortwocities]

Could be, under a fault condition, but wouldnt you be isolating the circuit before working on it?

TTC

 

[Spark123]

Not come across gold coloured plastic screws as of yet, what makes use them?
The only place I have seen nylon used is in a test area where the supply was separated.

 

[RF Lighting]

Not come across gold coloured plastic screws as of yet

&

 

[Lantash]

Just my ten cents worth, but I've always had a healthy dislike of metal fittings.

By earthing the hand of the person inserting a plug, metal faceplates greatly increase the severity of any shock received.

If there is anything wrong with the plug, the hand is wet, or maybe it's just an old type with no pin-sleeves and a finger slips under, then the user stands a good chance of a nasty burn.

There is also the issue that a disconnected earth on a metal lightswitch could link to live. The risk may be small if the wiring is in good condition, but hey, why have that risk when it's 100% avoidable?

Metal fittings are common in industry, but in that case they are normally on conduit, which greatly reduces the chance of a 'floating' earth. However, they still present a hand-earthing hazard as mentioned above.

Personally I think that the electrical regs we have to comply with now are completely and utterly OTT. But, domestic metal faceplates are one issue where I would raise questions.

I seem to recall an elderly relative metioning that even back in the days of DC switches, the brass screw-on cover type were rightly viewed with distrust, and operated with some respect for their possible liveness. The brown bakelite type, while revoltingly ugly, were the safe option. Some things don't change.

 

[plugwash]

Just my ten cents worth, but I've always had a healthy dislike of metal fittings.

By earthing the hand of the person inserting a plug, metal faceplates greatly increase the severity of any shock received.

If there is anything wrong with the plug, thse hand is wet, or maybe it's just an old type with no pin-sleeves and a finger slips under, then the user stands a good chance of a nasty burn.

otoh a shock that goes in and out the same hand is unlikely to be fatal.

besides even without the pin insulation you have to be pretty damn careless to get a shock off a BS1363 plug. The plugs have for a very long time had grips moulded in so you can grip them from the side and shouldn't have your fingers anywhere near the pins.

 

[Lantash]

otoh a shock that goes in and out the same hand is unlikely to be fatal.

True, though very few 'dry' shocks are fatal, most electrocutions occur in wet conditions, garden tools being a favourite. 'Dry' shock injuries are mostly burns, or impact/fall injury due to muscle spasm.

The other factor (which cannot be protected against) is that in a domestic environment it is not unknown for meddlers to disconnect earths, or take fittings apart and then leave fasteners untightened.

Therefore while some fittings (e.g. metal sinks) must needs rely on an earth for safety, it's better if earths are only relied-on where actually necessary.

 

[drewks]

Thanks a lot for these replies - very helpful all round

 

[securespark]

By earthing the hand of the person inserting a plug, metal faceplates greatly increase the severity of any shock received.

Umm, better not do any supp in the bathroom in case.....