2.5mm or 4mm extended ring

[scoobydoowantsu]

Hi guys,
and lasses if there is any.
I had a reply to one question couple of days ago, which was great.
but went to start work and encountered a problem.

I want to extend a ring around a 4m x 4m bedroom, which currently only has one double socket.
I wish to put 3 more doubles in.
Now,
I have been told the best way would be to split the current double into 2 singles and run a ring around the room.
Thats fine i can do that.
But, i presumed it would be 2.5mm cable, so , bought it.

Only to find out that the original socket in the room has I think 4mm to it.
Can i continue the ring using just 2.5mm to the other 3 sockets and then back to 4mm?
It is just a bedroom, so would only use maybe hair dryer, straightners, and a small TV.
Please let me know if you understand me?

lol
PS I think the house was built in the 70's
simon.

 

[PrenticeBoyofDerry]

I would always use the same CSA size of cable, as the original circuit.

 

[Taylortwocities]

Sounds like it may not be a ring. Could be a 4mm radial

How many cables in that existing socket?
How many conductors in the CPD in the consumer unit for that circuit?
How many amps for that CPD?

* CPD = circuit protective device. ie fuse, cb, etc

 

[scoobydoowantsu]

thank you, thats what i thought someone would say.
Can i ask, what problems can occur with using the smaller csa cable?

Also,
the existing cable is Black and Red, so could it be imperial sizes?

simon.

 

[scoobydoowantsu]

There are currently 6 wires in there, 2 red, 2 black and 2 earth
havent looked in the consumer unit.

 

[scoobydoowantsu]

I looked under the floor boards, and..

one of the cables goes off to another bedroom, the other off in another direction, most likely to another room.

 

[PrenticeBoyofDerry]

There are currently 6 wires in there, 2 red, 2 black and 2 earth
havent looked in the consumer unit.

Still could be either a ring or a radial.
The core colours changed a few years ago, to come in line with euronorm and new legal requirements with part p.
Nothing to do with metric/imperial sizes.

 

[PrenticeBoyofDerry]

I looked under the floor boards, and..

one of the cables goes off to another bedroom, the other off in another direction, most likely to another room.

You need to check back at the CU and see if the breaker protecting the circuit's cable has two red cables in or one.

 

[scoobydoowantsu]

ok.

So if its a ring or a radial, how does that affect what i want to do?
simon.

 

[scoobydoowantsu]

ok, I can check in the morning about the CU
What are the differences whether there is one or two wires?

 

[PrenticeBoyofDerry]

ok, I can check in the morning about the CU
What are the differences whether there is one or two wires?

If there is one cable it's likely to be radial
if two cable chances are it's ring final circuit, but you would need to test the circuit to be sure.
It's not unusual for a breaker to be found protecting two circuits and has been known for a ring final to be protected by two protective devices.
You could also check all the outlets on the circuit and see if you come to one that has just got one set of red,black and earth(CPC) cables. Then it's a radial providing it's not a spur from the circuit.
Confusing is it not!

 

[scoobydoowantsu]

OMG
Thanks guys so far.
So, what you're all telling me is that I CANT just use this socket to create a ring around the room for my 3 extra sockets?
When you sau "test" the circuit, with what?
simon

 

[PrenticeBoyofDerry]

You need to do a continuity test, this will help determine what the circuit is.
http://www.tlc-direct.co.uk/Book/8.4.2.htm

 

[scoobydoowantsu]

Can i please ask how a continuity test will help?
I am not looking for a break in a circuit, i need to know if i can split this double socket into 2 singles and create a ring?
There are 2 pairs of wires there, so i was told i could run a spur, but i need more than just one more socket.
simon

 

[PrenticeBoyofDerry]

We are trying to determine if the circuit is a radial or ring and continuity test will help us do that.
You can run a fused spur without splitting the circuit, but I would try to extend it.
If it was a radial circuit you can find the end socket on the circuit and just extend from there if it is suitably located. if it's a ring we need to break in to it!
You can split the sockets in to double outlets!