Adding two new 13a sockets to ring main Ask questions and find answers to many subjects relating to electrics and electrical work

[mawallace]

I have a electric socket which is recessed into the wall.

I want to add two new 13a sockets, which means I need to extend the ring main.

I thought I would remove the existing socket, add a junction box at that point, and then surface mount the new sockets.

The problems I am hitting are:-

i. Junction box - is there any junction box which would let me add this other the recessed back plate of the electric socket?

ii. If not, are there any ways I can add a surface mounted socket backplate over the existing 13a backplate, so I can then add wires coming out of the socket to the new sockets?

[ericmark]

To extend a ring final step one is measure the loop impedance to see how close to the limits it is already, the modern MCB is two devices in one, and if you exceed the limit then the magnet part may fail to work. So disconnection time can jump from 0.01 seconds to 30 seconds by just adding an extra meter if already on the edge.

The way I do it is to use grid switch modules, a double socket can become two single sockets in the same face plate which allows you to split the ring final and add more sockets.

The same method will allow a socket, switch and fuse and then you can add as many sockets as you like as a fused spur.

For a ring final looking at around 1.4 ohm with a fused spur more like 4 ohm so unlikely you would exceed the limit.

Other consideration is RCD protection, all NEW sockets require it, so using a RCD FCU allows new sockets to be RCD protected but old ones remain as they were.

[mawallace]

To extend a ring final step one is measure the loop impedance to see how close to the limits it is already, the modern MCB is two devices in one, and if you exceed the limit then the magnet part may fail to work. So disconnection time can jump from 0.01 seconds to 30 seconds by just adding an extra meter if already on the edge.

The way I do it is to use grid switch modules, a double socket can become two single sockets in the same face plate which allows you to split the ring final and add more sockets.

The same method will allow a socket, switch and fuse and then you can add as many sockets as you like as a fused spur.

For a ring final looking at around 1.4 ohm with a fused spur more like 4 ohm so unlikely you would exceed the limit.

Other consideration is RCD protection, all NEW sockets require it, so using a RCD FCU allows new sockets to be RCD protected but old ones remain as they were.

Thanks for the idea, but I'm not sure where you can get a double electric socket for the grid system. Can you please say how you convert the double socket to two singles using the grid system

[ericmark]

Two of these http://www.screwfix.com/p/lap-13a-1-gan ... hite/21218 and one of these http://www.screwfix.com/p/lap-2-gang-fr ... hite/90455 will give you two single sockets same size as one double.

[mawallace]

Two of these http://www.screwfix.com/p/lap-13a-1-gan ... hite/21218 and one of these http://www.screwfix.com/p/lap-2-gang-fr ... hite/90455 will give you two single sockets same size as one double.

That's brilliant. But where do they sell the mounting box. I've looked and can't see any

[ericmark]

If there is not already a box then you may as will use a twin (not double) back box and two independent sockets then more room.

See http://www.screwfix.com/p/appleby-galva ... At-88P8HAQ at screwfix I googled twin back box, then you also retain switches.

What I did in mothers house was to remove plaster only for the back box and use a plastic one see https://www.electricalsupplies.co.uk/mk ... AnvB8P8HAQ Although there is a little of the box above the surface of plaster, it looks as if you have just used thick sockets, the other option is not to extend ring but have a fused spur.

I found one socket was an unfused spur and I wanted to add more sockets from this point so I swapped for a double socket and using the grid system I have a switched socket and a fuse at original, and all sockets from that point are now fused spurs.

In my case all is already RCD protected, if not using a RCD FCU means new sockets are RCD protected.