Metal faced sockets and earthing

[Barney78]

Is it ok to not run earth to the terminal on a back box sunk in to the wall on metal faced sockets as long as it is run to the terminal on the socket itself so that the face is earthed?

I assume that the contact between the screws, the face plate and the back box mean that if the front is earthed all of it is?

 

[bobapcoed]

You're right they are all earthed but the real way is to earth both the S/O and the box. Not much to do it right.

 

[Big_Spark]

If you have metal faceplates then both should be earthed for safety. It's a bit of a grey area as some will say it is not required, whilst others will.

 

[Barney78]

no worries i'll just do both, it just makes it a bit less fiddley if there isnt a wire connected to the back box

 

[Qedelec]

Just for reference the back box is regarded as 'an exposed conductive part' and therefore must be earthed.
Earthing the face plate will earth the box when screwed up but not whilst an electrician is working on it, so its much better to add 6" 1.5mm² single from fitting to box.

 

[Barney78]

are you suggesting that people work on sockets without isolating them from the supply first? tut tut tut.

 

[Qedelec]

No Barney Bear that was not what I said, please read the post properly.

Hazardous voltages can appear on metalic parts for any number of reasons not just because some numpty forgot to isolate the circuit.

THIS is the reason you should earth back boxes.
E.G. The sheathing ons a cable is in contact with the back box and someone put a nail through the live and capping. That live may not be the one feeding the socket.

This is an important point that MUST be emphasised. Always earth the back box.

 

[plugwash]

iirc one of the guidance notes says you can use the faceplate screws to earth the backbox as long as it has at least one fixed lug but many sparkies think an earth wire should be taken to the box anyway.