Surface mounted metal sockets and boxes

[d000hg]

I really like these and am usually then in my garage. But am finding it a pain that you have to add a little earth wire to the terminal on the box. Of course it needs to be earthed but what I don't get is why they don't earth the face plate to the earth terminal, then have the box automatically earthed when it touches the face?

If you're going to add two sockets, now you've got 3 earth wires to get into one hole.

 

[daggermark]

Presumably you cannot absolutely guarantee a full earth connection in the situation where you are unscrewing the face plate - a live wire could be touching the back box and suddenly you've lost your earth. Better safe than sorry! It can be quite difficult to get 3 earths into 1 terminal, but I think some have an earth-per-gang, and you can just put the back box earth into either one?

 

[d000hg]

I never thought of that scenario... Good point. Though why are you unscrewing it when it's live...

 

[daggermark]

I certainly wouldn't, but I've seen plenty of decorators do it!

 

[AndyPRK]

Not metal clad ones they don’t

 

[flameport]

Metalclad sockets and their boxes are not bare metal - they are a grey paint finish.
Paint doesn't conduct electricity.

 

[d000hg]

Then the box doesn't need to be grounded, just like plastic ones don't!

 

[bernardgreen]

Then the box doesn't need to be grounded,

paint scratches

 

[d000hg]

How unlucky does a guy have to be

 

[DetlefSchmitz]

A layer of paint simply does not count as insulation and you will not find any specification which says it does.

 

[AndyPRK]

If you watch from 7 minutes

This is how a "professional" sparky does it. (wasting quite a lot of cable) and only having 2 conductors in the terminal.

Another way of doing it, is to put 2 wires into the back box, and 2 wires into the front plate. Not a fan of this method myself

 

[securespark]

Am I missing something?

Why not put the ring final cpcs in the socket terminal along with a link to the box?

Socket terminals are usually bigger than the back box terminals.

 

[securespark]

Also, how is he going to test the BG RCD?

Conduit has metal clips?

 

[d000hg]

If you watch from 7 minutes

This is how a "professional" sparky does it. (wasting quite a lot of cable) and only having 2 conductors in the terminal.

Another way of doing it, is to put 2 wires into the back box, and 2 wires into the front plate. Not a fan of this method myself

That's a neat little trick, I guess.

Unrelated but he has two cables coming into the backbox. Is that because this is a double-pole unit (I do not know what that means) or simply because he is using the socket as a junction box to avoid having a separate one cluttering things up?

 

[daggermark]

Most backboxes would have 2 cables coming in, unless the socket was a leaf on a radial or it was a spur off a ring.