Adding sockets to downstairs ring main.

[henryb1]

Good afternoon all.

If possible I want to add sockets to an exsisting downstairs ring main.

There is a socket avaialble with 2 x 2.5 te connected to it. Would it be possible to use 2 x junction boxes to break into both cables then add 3 new sockets? How do you establish which cable is "supplying" the circuit and which is "returning"?

Thanks in advance x

EDIT to say: I want to do it like the diagram below, but i am concerned about the "supply" and "return" cables.

 

[PrenticeBoyofDerry]

If the junction boxes are easily accessible you can, if the junction boxes are not accessible you either need to avoid making joints, by installing longer lengths of cable from the existing socket outlets or joining your cables using either crimps or solder.

http://www.diynot.com/wiki/electrics:extend_ring

 

[Chri5]

If you break the ring at the CU you should end up with a radial that travels round all the sockets. If you then seperate the 2 x TE cables at the socket one will have zero continuity between N-E and the other will have continuity.

Or working live one will have power the other won't.

Best job is to no have j/b's or crimp joints and feed new TE's out from the last existing socket before the additional sockets and the first existing socket beyond the additional sockets.

 

[electronicsuk]

You say there is a socket available that the ring final runs through, and yet this doesn't seem to match your diagram. Assuming you drew it to reflect the physical layout of the sockets to some extent, should both ends of the ring not be returning to the same socket? All you'd need to do to retain to ring is remove one of the existing cables from the socket you'll be taking the supply from, use crimps or 30A terminal blocks to extend it onto a new section of cable, loop through your new sockets, and return back to the original socket and terminate the new section of the ring into the existing faceplate, along with the one remaining old leg of the circuit. That probably would be better illustrated, but I can't really be bothered to draw it right now.

The above method is preferable to JBs, as the crimps/screw terminals can be pushed into the backbox of the socket (assuming it's deep enough) and yet still remain accessible for inspection by removing the faceplate. It's not quite as neat, however, as taking the feed from one socket and returning to an entirely different socket to complete the ring. And of course, it may mean having excessive cable depending on the physical layout of the circuit.

 

[ban-all-sheds]

Another approach, the feasibility of which depends on what type of sockets you have, and how visible, is to replace a twin socket with two singles in a dual box, thus giving you two separate places to wire the start and end of the circuit extension.

And for any future designs, consider the fact that if you had had a radial you could have branched off from any socket(s) you liked in order to add new ones.

 

[LoveRocket]

And for any future designs, consider the fact that if you had had a radial you could have branched off from any socket(s) you liked in order to add new ones.

Ain't that the truth. That's why it staggers me that people still install rings.

Sorry if I've been on a bit of an anti-RFC campaign today, but they are so awful....

 

[Taylortwocities]

How do you establish which cable is "supplying" the circuit and which is "returning"?

There is no concept of supply and return legs in a ring.

If you take the live conductor. Both legs start at the consumer unit and each leg supplies each socket. So at a socket, if you were to test both live conductors then both will be supplying 230volts. Follow the live conductors on your diagram and you'll see.

AC isn't as easy to explain as DC (eg a torch and battery) but simply you can envisage the 230 volts going out on the live from your consumer's unit and returning on the neutral.

At this point I make a plea to the "wise owls" of this forum not to go into AC theory and phasor diagrams. It would add no value.

Footnote: What you are trying to achieve is detailed on the WIKI. See http://www.diynot.com/wiki/electrics:extend_ring

 

[ban-all-sheds]

Ain't that the truth. That's why it staggers me that people still install rings.

I really think they missed a trick with the 17th.

They could easily have made it so that in installations not intended to be under the supervision of a skilled or instructed person, no new ring finals could be installed.

 

[Taylortwocities]

Perhaps we could start with
"ring final circuits may only be installed by a skilled person".

 

[OwainDIYer]

I like rings. I think they're wonderful. By all means put in a separate circuit for the kitchen, and obviously they have to be appropriate for their intended use, but I like rings.

If for no other reason than 32A rings mandate fused plugs and effectively stop using nasty continental plugs.

 

[ban-all-sheds]

So do 20A radials.

 

[plugwash]

Afaict how big a circuit standard continental plugs are allowed on varies across europe. I beleive some countries allow them on circuits as high as 32A!

Getting back to the subject of rings the thing is despite their theoritical faults they rarely seem to cause any trouble in practice. I put a lot of this down to the fact that we design circuits based on the continuous rating of cables even when they will only see intermittent use.

The thing I don't like about 20A radials is they only allow one big load. IMO that means if you use 20A radials you need a circuit for each habitable room and several for the kitchen.

 

[ban-all-sheds]

Afaict how big a circuit standard continental plugs are allowed on varies across europe. I beleive some countries allow them on circuits as high as 32A!

That's up to them.

Our plugs are fused, and they remain fused when used on radial circuits.

Getting back to the subject of rings the thing is despite their theoritical faults they rarely seem to cause any trouble in practice. I put a lot of this down to the fact that we design circuits based on the continuous rating of cables even when they will only see intermittent use.

The same applies to radials.

The thing I don't like about 20A radials is they only allow one big load.

So?

IMO that means if you use 20A radials you need a circuit for each habitable room and several for the kitchen.

1) So?

2) How many people have a large load in each habitable room?

3) If you use a ring for a kitchen where you postulate several large simultaneous loads how do you ensure compliance with the final proviso of 433.1.5?

 

[LoveRocket]

20a radials are not really great for a kitchen, so why not a 25a or 32a radial on 4mm or 6mm cable?

I agree with Banal on this, and the logic does seem to be flawed:
We all agree that a ring is not good where there's going to be several large loads
We all agree that a 20a radial (on it's own) isn't much good for a kitchen
So the only time we should still install rings is for kitchens!

Hmmmmmmmmm........

 

[PrenticeBoyofDerry]

I like rings. I think they're wonderful.