Adding additional power sockets

[LooPrEvil]

My bedrooms only have one power socket in each room and I would like to add another 1 or 2 sockets to each room.

I think the existing layout was probably dictated by the electrician wanting to use as little cable as possible.

My question is, if I extend the existing ring main, can I just spur off from a junction box taken from the ring, or do I need to run the ring to and from each additional socket?

Also what height would you suggest I set the sockets into the walls, as I am led to understand that there is now a minimum height from the floor. My existing sockets are about 150mm from floor level.

Thanks

 

[PrenticeBoyofDerry]

It depends what type of circuit you have, there are two main types.
RFC (ring main)
Radial.

Junction boxes are no longer allowed in areas that are not easily accessible, so if the joints are going in to ceiling void and you/electrician has no access to them for inspect/test it's a no no.
The best solution would be to extend you RFC from socket to socket, this may mean removing some floor boards and replacing new lengths of cable to make it work.
Other options are to take a spur from a socket, only one spur per socket is allowed and no spurs from sockets that are already spurs.
Or you could spur a 13A Fused Connection unit from a socket on the existing RFC circuit and run as many sockets from that as practical/logical for the 13A load.

 

[Adam_151]

You can spur from a joint box but each spur may feed only one sockets, but joint boxes must be accessible i.e. not under the floor. The ideal solution would be to add your new sockets to the ring, if you are chopping cables up the wall to your new sockets then you might as well re-route the ring (you might not even have to chop upto the existing sockets, if its in oval tube it'll pull through, if its capping it 'might', if its in the render it won't)

You should put the new sockets at the same height as existing, anything else would look odd. Part M does not require you to put them at 450mm in this situation!

 

[PrenticeBoyofDerry]

Oh yes socket height, personal choice really, you not required to comply to Part M of building controls as Adam_151 has mentioned.
But the socket should ideally be fitted so no stress to the plug/plug flex is given and no worse than the current height of the sockets.
I would consider what they are being used for and install them suitable for that application. So it is easy for you to remove plug or operate switch and the flex of the equipment is not going to cause additional hazards.

 

[LooPrEvil]

Thanks for your most helpful replies PBod & Adam.

As the junction boxes would be under the floorboards making acess difficult, I will therefore add the new sockets to the ring, and maintain the existing height.

 

[Taylortwocities]

There is a guide on how to extend a ring final WITHOUT USING JUNCTION BOXES.

Its in the WIKI

Here's a short cut
//www.diynot.com/wiki/electrics:extend_ring

 

[LooPrEvil]

Thanks TW. That is what I understood was required. As the original wiring is only short runs I am now hoping that in essence, if I can trace how the cable runs to the CU I might as well replace it all with the latest wiring code (brown / blue rather than the existing black / red).

Thanks again to all for your useful advice.

 

[Taylortwocities]

Thanks TW. That is what I understood was required. As the original wiring is only short runs I am now hoping that in essence, if I can trace how the cable runs to the CU I might as well replace it all with the latest wiring code (brown / blue rather than the existing black / red).

Thanks again to all for your useful advice.

You can do, if you wish. There's no point if the existing wiring is in PVC and looks in good condition.
When you have finished you MUST check that you have continuity on all of the ring conductors (eg use an ohm meter to test from one red/brown at the consumer unit to the returning leg and then do this for the black/blues and the earth connection.)
With ring circuits it is important to do this as its easy for one conductor to be disconnected. This means that the circuit will APPEAR functional as the sockets will work; but the circuit can easily be overloaded.

There's a guide to testing ring circuits HERE.

 

[LooPrEvil]

Thanks again TW.

The reason I considered changing all the cables whilst extending the circuit is because I believe it is about 30 years ago when it was last rewired.

In terms of testing the circuit, would one of these be useful:

http://www.maplin.co.uk/mains-socket-tester-9800

 

[Taylortwocities]

In terms of testing the circuit, would one of these be useful:

http://www.maplin.co.uk/mains-socket-tester-9800[/QUOTE]

That won't tell you if the ring is correct and all of the connections are done properly. The lights will come on and tell you there is voltage there but (as outlined above) you will still get a 'good' reading from one of those even if a wire is not connected.

To do it properly you'd need some very expensive test equipment, but as a minimum you'll need one of these:
http://www.maplin.co.uk/domestic-multimeter-37279

 

[LooPrEvil]

Thanks TW.

I bought an RS multimeter years ago, but to be honest I would not know how to use it for testing the circuit. The one I purchased only gets used for the occassional testing of fuses and bulbs etc. It probably has a lot more functionality than that Maplin one has, but has turned out to be a very expensive 'beep' tester, as that is virtually all I use it for (cost about £100 over 20 years ago).

 

[PrenticeBoyofDerry]

You most also place a notice up near the CU/Fuse board stating you have two types of colour cores.

Stating:
This installation has colours to
two versions of BS 7671

Great care should be taken before
undertaking extension, alteration
or repair that all conductors are
correctly identified

http://www.tlc-direct.co.uk/Main_Index/Cable_Accessories_Index/Cable_Colour_Labels/index.html

 

[securespark]

Junction boxes are no longer allowed in areas that are not easily accessible

If you absolutely have to, you could use a JB with the marking MF (Maintenance-Free) on it, as per Amd 1.

Stick to the old height.

You can do spurs, as long as the number of spurs does not exceed the number of sockets on the RF (assuming it is an RFC).

 

[LooPrEvil]

Thanks to all for your advice to date. I had intended using JBs to extend the ring, however I have am taking your advice and will extend from existing sockets as well. At the same time I am also going to replace the existing wiring on the ring as it will not take much additional work (there are only 4 sockets currently on the circuit so I will be breaking into 2 of them anyway so I might as well do them all). I will end up with 9 or 10 sockets on the new ring.

I am hoping to to replace the feeds from the CU if I can trace how they go from upstairs sockets to the CU! This will mean all wiring on the circuit will be blue / brown rather then combined with red / black.

Can I please ask, what is the difference between a single and a double pole 13A switched socket?

Thanks

 

[Taylortwocities]

Can I please ask, what is the difference between a single and a double pole 13A switched socket?

Thanks

The single pole only switches the live, the double switches live and neutral.

There's very little price difference. I would go for DP if you are renewing.