brass sockets

[Stephen]

Hello,

My FIL has fitted brass sockets. Perhaps it's me, but I can't understand why anyone would want to get a socket made of metal and connect it to 240v! But back to the point: they don't fit on the wall. I have had a look at some old posts here and they hint that metal sockets leave less room behind for the wires, so I guess this is his problem. Why would a metal socket be deeper? After all, the three pin plugs are the same length no matter what socket they are inserted into.

What is the best solution to this? I haven't seen it so I don't know how long the wires are or how deep the box is. Hopefully the wires could be trimmed if there is excess; otherwise is it a matter of chiseling out the back box and fitting a deeper one?

Thanks, Stephen.

[The Medway Handyman]

My thoughts exactly!

Do check that the earth is connected, I've found several metal switches & a few sockets where is wasn't...

[Andy Dingley]

Metal, or metal-faced plastic?

Metalclad boxes should be earthed, and if they aren't then it's simply carelessness by the installer. Metal-faced plastic (and the crappy ones from Aldi in particular) seem to depend too much on the quality of their manufacture. I've seen a bunch of these where the metal is very poorly attached and has fallen off, in a way that suggests its earthing was quite tenuous to start with.

[js.b1]

Some sockets require 35mm backboxes. Indeed, if your wires enter from the rear then it is a good idea to actually use 42mm backboxes due to bend-radius, risk of wire crushing and space.

If the socket fronts are not sitting to the wall they contravene reg- something re IPx4 on top (applies to sockets like anything else). Additionally they may be crushing the wires behind, which is a good way of a) having nuisance RCD tripping or even a fire since hot debris can drop out of the box vs be contained b) having to replace the cable(s).

Homes From Hell last night had a bizarre double fire - first a heater for a hot-tub burnt the "barn" down, and then a (stalled) compressor on a fridge freezer took out the entire building whilst they were away on holiday. Mashing wires behind a socket is not acceptable, fit deeper boxes (fold the old ones in, remove, refit deeper 35mm boxes) or fit "non-flat" sockets. If there are 3-cables into any of the boxes or rear-entry cables, you need to think about using 42mm with "flat- front" sockets.

[Mike Clarke]

Metal sockets usually have a much thinner faceplate than plastic ones so the whole socket assembly sits further back in the box leaving less room for wiring.

[John Rumm]

So long as its earthed, its not a problem.

Depends on the type. Something like:

be much the same as a plastic one - the socket itself protrudes in front of the wall 7 or 8mm and hence gives that much extra space behind. The problem comes with the trendy "flat" ones:

are really flush to the wall without any front protection, hence need deeper back boxes.

Basically yes, you will be hard pressed to get a flat face socket sitting flush on a 25mm back box.

[Dave Plowman (News)]

Because plastic looks and is cheap?

Different designs of sockets require different back boxes. The instructions provided with them - or in the maker's spec - will say what's needed. Most are happier with 35mm types.

[Stephen]

Another reply said not to shorten the cables so I suppose there must be an art to getting the right length: not too short that it is difficult to insert and screw them up but not so long that they get crushed and squashed behind the socket. What's the problem there: overheating? Is there a rule of thumb for the correct length?

On a different matter, if you use a surface box, often you knock a square out using a large screwdriver. If you use 13mm trunking I guess that's roughly the size of the knock-out. If you don't use it, how do you seal the gap to make that IPx4 compliant?

I worked in a shop that had been destroyed by a fire caused by the fridge. If you go on holiday and switch everything else off, you have to leave the fridge and freezer on, so I don't know what you can do about it.

I don't think these sockets are flat. I haven't seen them yet but I guess they are Georgian style brass ones.

I was interested that you said fold them in. How do you do that: hit them with a cold chisel? Is there a magic way to take the old one out and the new one in without removing too much of the surrounding plaster?

Thanks, Stephen.

[Dave Plowman (News)]

I make them about 9" long. (From where the cable enters the back box)

[Tim Watts]

I follow a rough rule of thumb that says the cable should be about a diagonal of the box in length.

I then form the conductors into some rough approximation of a semicircle between the cable entry and the location of their terminal.

This gives me enough slack to work on the plate, but as it is replaced, the conductors fold back aka the coils in a spring which avoids unnecessary pressure and wire strain.

I agree with the sentiments re rear entry. I have 35mm boxes, plus

5-10mm of plaster and two have rear entry and they were getting towards being a little tight with normal plates (GET Ultimate plastic). If the box was hard level with the surface of the plaster and I'd tried to use metal plates, it probably would have been tighter than I would like.

The main problem with crushing is damage to the insulation and the possibility of fracturing the conductor.

There is a secondary problem with T+E depending on how it is bent to do with the conductors cutting through the insulation over time. This would be more of a problem with a bend "on the edge" (ie the hard way with T+E) where the outer conductor may be under tension. Not seen that myself, but I've seen it mentioned somewhere).

[ARWadsworth]

I just take each cable to the furthest corner of the back box and add on the amount needed to strip back the insulation for the connection. So I have wires of different lengths depending upon their cable entry positions.

One thing that does help is not having two T&E coming through the same entry point.

[Stephen]

Oh, that seemed a bit long to me.

I've been and had a look at the socket. It is not a flat type but it looks like it is a spur because there are three cables and there is not enough room for all of them.

I think a bigger back box with do it. I guess it's got to be done by hand since you can't plug the sds drill in if the socket isn't on the wall ;) Unless I find a socket on a different ring and get out the extension lead.

Thanks, Stephen.

[Dave Plowman (News)]

If the cables enter at the centre of the box, that's long enough for them to go to either side then fold back to the terminals - regardless of where those are on the fitting.

Hence the need for 35mm boxes. I never bother with smaller.

You could pull all the cables out and use a 30 amp chocolate block temporarily. Then plug in to a different socket on the same ring.

[ARWadsworth]

Ooh err missus.

[Stephen]

I took the advice of this group long ago and have only used 35mm boxes ever since.

And make sure not to chisel the choc box! A good idea though, thanks.

Thanks, Stephen.

[Stephen]

Thanks. I never knew that. I thought it was overheating in a confined space or something. I hadn't realised they could fracture.

Thanks, Stephen.

[Tim Watts]

If one gets caught in a bend then squished flat, it's quite likely. Not the first time the box goes on probably[1] but more likely the 2nd or

3rd time as the copper work hardens and is subjected to extreme repeated bending. [1] But more likely at the terminal - the screw biting in weakens the conductor to some extent and it's not too hard to get a fracture here, even with space.

Out of 3 rings and about 25 sockets, I had one neutral do that even though my standard of assembly is "careful". The end-end test picked that up straight away - and that is a meaningful test that can be done with a basic multimeter (disconnect all the ring conductors at the CU - then as 3 separate tests, measure L-L, N-N and E-E.

Spots breaks and crossed wires straight away.

[Stephen]

Just to follow-up, he's decided if we are going to change the back box then we may as well upgrade it to a double. I've just bought a brass socket from Tool station. The strange thing is, it comes with a plastic "washer" that it tells you to insider between the socket and the wall. I never expected that. It means that it keeps the metalwork of the socket does not touch the metal work of the back box, though the screws will provide contact. What is the reason behind this?

Thanks, Stephen.

[Jeff Gaines]

It keeps the Brasso off the wall decorations.

[ARWadsworth]

The (washer) gasket is there to stop the socket getting tarnished by the plaster. This should not be a problem if the plaster is dry/painted/papered.

The socket front is very unlikely to be touching the metal back box unless you fit the backbox flush to the plaster. Even then the socket front might still not be touching the backbox depending on the design of the socket.

The screws that hold the front to the backbox will earth the backbox although there is no reason why you cannot add a "fly lead" from the sockets earth terminal to the backbox earth terminal if you want to.

Cheers