Three wires into a junction box and one back out?

[king2001]

Hello all,

This is probably a very simple question for you to answer but my knowledge of wiring is fairly limited and I want to make sure what I'm doing to right.

Basically I am moving a light switch and double socket to another wall. Now the switch is no problem as there is plenty of cabling to allow the move but the socket is more difficult.

There are three cables going to the socket and only one of them is long enough to reach the new position. Therefore I'm going to have to extend the other two by using a junction box as I cannot trace them back without taking up a stack of floorboards and I do need to get this done pretty quickly.

Also I have found that it is a complete nightmare trying to get the wires back into the socket and much swearing has been heard when trying to attempt this!

So my question is can I put the three wires into a junction box and then feed only one out into the socket, as shown in my drawing below, or does this violate some law unknown to me!

Hope someone can help!

 

[THRIPSTER]

Looks like your original wiring is ring main and a spur or perhaps a spur with a couple of spurs.

You should get this work done by a qualified electrician as by terminating into a junction box and going on with a single cable to the sockets may overload the cable. I assume you are not profficient at calculating circuit loads and suitable cables?

In practice, you could do what you say and if you have any gumption about you you will ensure that the circuit is not overloaded. However, what happens when you sell the property and the subsequent owner is not aware of what you have done? Better get that electrician in.

Regards

 

[Chri5]

The 3 wires are likely to be 32a ring main (1 cable 'in', 1 cable 'out') and a spur off to a socket or fused spur.

You should NOT do what your intending because in creates 2 spurs, even though the ring is complete as a circuit.

Have you got a meter for 240v reading / test?

If so, isolate the circuit via switching the fuse off at the consumer unit / fuse board.

Undo all the wires and (safely) separate the live and neutral wires. Switch the fuse back on.

With a meter you can then go across each cable and will find 2 cables that are reading live 230-247v, the 3rd cable will be dead.

You've now identified your ring in, ring out cables and the spur cable.

You can now wire to the new socket position with two cable feeds to extend the ring, the cables should be terminated back on to the ring in, ring out cable that has been identified and the spur can be re-terminated.

The existing socket point now becomes a junction box and must remain accessible for service and mtce work. Buy a double blanking plate to cover the junction and use an indelible marker pen to mark up the cables for future reference.

If in any doubt offer the work out to an electrician, saving money by DIYing is prudent only if you have the skills to avoid a unsafe installation or even electrocution

 

[king2001]

Thanks for the quick response thripster and chri5.

Basically if I want to do this myself then I would have to use a junction box for each of the two cables that are too short and have all three cables end in the socket as previously done.

Obviously I was just trying to make everything nice and tidy but my little knowledge of electrics is plainly nowhere near enough!

Out of interest if I wanted to get rid of the socket completely how would I go about that. Do I just put all three cables in a junction box or do I have to leave them where they are and fit a blanking plate?

Your thoughts will be much appreciated!

 

[davelx]

The point made about making the joins in the existing socket box and using a blanking plate is that the joints must be accessible.

If you use junction boxes, where are you going to put them? On the wall? - OK. Under the floor? NOT OK, as not accessible.

 

[king2001]

hi davelx,

Yes the junction boxes would be under the floor so this is obviously not the best solution. Again I'm trying to make everthing look nice and tidy!

 

[davelx]

Ideally, replace the cables with longer ones from the sockets on each side of the one you want to move, and replace the cable to the spur with a longer one that will reach one of the sockets on the ring. No cable joints needed.

Alternatively, if you want to totally get gid of the existing back box, you could extend all the cables under the floor using crimp connectors and heat shrink, which would not need to be accessible. You would extend the spur cable to reach a suitable socket on the ring - it does not have to be the one you are moving, any socket that does not already have a spur off it will do.

But to use crimps you will need to get a proper ratchet crimping tool and blue (for the phase conductors) and red (for the CPC) butt crimps, plus heat-shrink. It takes a little practice to make good joints - and you need them to be good joints. There's a thread around that descrbies this in detail.

If you are handy with a soldering iron, you can also use soldered joints and heat shrink.