Attaching wall sockets in place of electric fire cable

[Andromedus]

Hello everyone. I'm just starting a project where I'd like to replace an existing electric fire place with a new tv wall (a false wall into which I'm going to fit a tv and other AV equipment). I'm just wondering how to handle the electrics. The existing fire place has a bare cable coming out of it, where an electric fire would normally be fitted. (It's a new house, this is how the builders left it).

My question is, can I use this cable to fit some new sockets (hidden inside the new wall), so that I can plug in the various bits of equipment? There are six things which will need plugging in (all of them are low power - the total current won't exceed 13 Amps).

Some more information about the cable I want to use as I assume that is important. It is a flat, grey cable, with a blue wire on one side, a brown on the other, and a bare Earth wire in between:

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• Andromedus
• 2 Aug 2014
• 1

Just to the right of the fireplace is a wall switch, with a fuse:

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• Andromedus
• 2 Aug 2014
• 1

There's also a double wall socket about two meters to the right of this switch. Am I right in thinking that this switch is a fused switched spur from the double wall socket?

Any advice is much appreciated - thanks very much!

 

[AndyPRK]

Assuming the cable comes from that fcu, (which would be logical) then yes you could fit a socket to it. (Or as many as you require)

 

[JohnW2]

The existing fire place has a bare cable coming out of it, where an electric fire would normally be fitted. (It's a new house, this is how the builders left it). .... There's also a double wall socket about two meters to the right of this switch. Am I right in thinking that this switch is a fused switched spur from the double wall socket?

As Andy has said, that's the most likely explanation, but you would really need to get that confirmed before doing as you propose (which would then be fine).

The builders really were very 'naughty', to say the least (I could talk about regulations and laws), to leave that cable like that!. Also, it looks from your pictures as if the route that cable presumably takes to the FCU is not within the 'safe zones' required by the regulations.

Kind Regards, John

 

[Andromedus]

Thanks guys.

To clarify, what exactly is it that I need to check - that the bare cable does come from the fcu, or that the fcu is a spur from the double wall socket?

Thanks.

 

[JohnW2]

Thanks guys. To clarify, what exactly is it that I need to check - that the bare cable does come from the fcu, or that the fcu is a spur from the double wall socket?

You need to check both of those things AND, strictly speaking, also to make sure that the double socket is actually part of a ring (or radial) circuit - i.e. not already itself a spur (spurs from spurs are not allowed).

Kind Regards, John

 

[Andromedus]

Ok - thanks, I really appreciate your help with this.

To check both of those things, would the following suffice?

1) Connect the bare cable to a lamp, then turning on and off the fcu switch will determine whether the cable is attached to the fcu.

2) With that lamp turned on, plug a second lamp into the double socket. Go to the garage and switch off the switches one by one in the control box. If both lamps go on and off at the same time, then they must be on the same circuit, right?

Would those checks be sufficient to prove it is safe to attach a new socket to the cable?

Thanks.

 

[JohnW2]

To check both of those things, would the following suffice?
1) Connect the bare cable to a lamp, then turning on and off the fcu switch will determine whether the cable is attached to the fcu.
2) With that lamp turned on, plug a second lamp into the double socket. Go to the garage and switch off the switches one by one in the control box. If both lamps go on and off at the same time, then they must be on the same circuit, right?

Yes, that would answer those two questions satisfactorily. It would not confirm taht the double socket was not already a spur (in which case the FCU should not have been spurred off it) - but since it's a brand new house, one would hope that it had ben wired correctly, and in compliance with regulations.

Would those checks be sufficient to prove it is safe to attach a new socket to the cable?

It certainly wouldn't be any less safe than connecting an 'electric fire' to the cable!

Kind Regards, John

 

[Andromedus]

Excellent! I'm confident that the builders wouldn't have taken the fcu for the electric fire off an existing spur, (despite the naughty bare wire, they are still fairly reputable builders!) so I think that's all bases covered.

Thanks again - you've been extremely helpful.

 

[JohnW2]

Excellent! I'm confident that the builders wouldn't have taken the fcu for the electric fire off an existing spur, (despite the naughty bare wire, they are still fairly reputable builders!) so I think that's all bases covered. Thanks again - you've been extremely helpful.

You're welcome - as I said, I agree that it's very unlikely that they will have 'spurred off a spur' in a new build. However, before you get too carried away with your confidence in the builders, as I said, it looks as if the route from that cable to the FCU may possibly not be compliant with regulations (although it may be OK if the pipe/conduit the cable is in is metal and goes all the way to the FCU).

Kind Regards, John

 

[Andromedus]

Out of interest, why do you think that cable may not be compliant - because it doesn't run horizontally, or does it need to be a certain height?

Is there anything that I should be mindful of when fitting the new sockets to the cable (keeping in mind that the new sockets will be concealed within a false wall, accesible through a small access panel) - like height, position?

Thanks.

 

[JohnW2]

Out of interest, why do you think that cable may not be compliant - because it doesn't run horizontally, or does it need to be a certain height?

Unless mechanically protected (e.g. within steel conduit) for their entire length, cables buried <50mm deep in walls must travel in 'safe zones' - the relevant ones in this case being those which are either vertically or horizontally aligned with the accessories (sockets, FCUs, switches etc.) to which they are connected. It looks as if your cable travels either diagonally or else has a 'corner in it, with the horizontal part of the run not aligned with the FCU. However, as I said, if the cable is adequately mechanically protected, that would probably be OK.

Is there anything that I should be mindful of when fitting the new sockets to the cable (keeping in mind that the new sockets will be concealed within a false wall, accessible through a small access panel) - like height, position?

The sockets (and anything else involved in the wiring - like switches or junction boxes) have to be adequately accessible for maintenance, inspection and testing. The regulations don't define exactly what 'accessible' means, but when deciding how to do it, have some thought for the person (who could be you!) who may have to work on any of the sockets etc. in the future! Hopefully, all cables behind your 'false wall' will be at least 50mm below its outside (room side) surface - otherwise there will be lots of new cans of worms to consider!

Kind Regards, John

 

[Andromedus]

Ok - so the new sockets (and the current fcu after the new wall goes up) will all be greater than 50mm behind the surface, and accessible via a small door, so I think I should be ok.

Great information - thanks.

 

[Andromedus]

Just a quick follow up - having investigated a little further, it appears that both the fcu and the bare cable run vertically up the wall to ceiling height in metal conduit.

I think that means that a) the wiring was indeed done in accordance with regulations and b) the fcu is probably connected directly to the ring main rather than spurred from the other wall socket as I'd initially thought.

 

[JohnW2]

Just a quick follow up - having investigated a little further, it appears that both the fcu and the bare cable run vertically up the wall to ceiling height in metal conduit. I think that means that a) the wiring was indeed done in accordance with regulations and b) the fcu is probably connected directly to the ring main rather than spurred from the other wall socket as I'd initially thought.

I would agree with (a) - at least as far as the cables you have identified are concerned. Your (b) is a possibility, but far from certain. There obviously should be at least two cables to the FCU (three if it is part of a ring) - one (or two, if part of a ring) from the supply (wherever) and the other to the load (which may be the 'bare cable'). However, it would seem a little odd that the 'output' from the FCU and the 'bare cable' should be sent all the way up the wall and joined (or maybe even a continuous cable) somewhere up there, given that the FCU and 'bare cable' are only a foot or two apart. I therefore wonder whether the FCU really does feed that 'bare cable'. Have you yet tried connecting something to the cable and seeing if the FCU operates it? If there is only one ('load') cable from the FCU going up the wall, it's still possible that the FCU is spurred from the socket.

Kind Regards, John

 

[Andromedus]

Ah, ok - I guess the fcu can't be directly on the ring then, because there are only two cables going into the fcu, not three. One goes into the 'feed' terminals and the other into the 'load' terminals.

The fcu is definitely connected to the bare cable, as I wired it into a socket temporarily and checked it with a lamp. I also checked that the lamp went on and off with the other sockets in the room when the switch on the CU labelled 'downstairs sockets' was flipped, so I know they are on the same circuit (and it also went off when I turned off the switch on the CU labelled 'RCD' circuits, which I presume means they are protected by a circuit breaker).

Does that mean it is a spur, after all?