3 core and earth sockets

Tactical DIY · 10 Jul 2021

Hello,
My house has 2.5mm 3 core and earth for the sockets. I'm adding an extra couple of sockets and want to make sure I'm using the correct cables.
Can someone confirm where the earth goes and which of the 3 "cores" are used as the live and neutral when wiring a new twin socket?
Thanks

securespark · 10 Jul 2021

Can you post some pictures of your sockets and cables please?

Pictures speak a thousand words.

JohnD · 10 Jul 2021

that's very odd.

What colour are the three cores, and how have you verified they are 2.5mm?

They're not lighting sockets, are they?

photos would be interesting.

Tactical DIY · 10 Jul 2021

It's definitely the "plug" sockets as I took the faceplate off.
The cable is 6243Y 3x1.5+1
Separate wires are

Bare copper with a green and yellow sheath
Grey
Brown
Black

JohnD · 10 Jul 2021

and you are in the UK?

Tactical DIY · 10 Jul 2021

Yeah.
When I took the faceplate off it definitely puzzled me.

Tactical DIY · 10 Jul 2021

securespark said:
Can you post some pictures of your sockets and cables please?

Pictures speak a thousand words.

JohnD said:
that's very odd.

What colour are the three cores, and how have you verified they are 2.5mm?

They're not lighting sockets, are they?

photos would be interesting.

I'll get photo tomorrow when I'm back at the house.
I just noted down the size and colours
The cable is 6243Y 3x1.5+1
Separate wires are
Bare copper with a green and yellow sheath
Green
Brown
Black

Read more: https://www.diynot.com/diy/threads/3-core-and-earth-sockets.574272/#ixzz70F1IRnGeknyhe

JohnD · 10 Jul 2021

might have been wired by an industrial electrician who stole the cable from work.

Although there are conventions for colours, you can't be sure what he has done. You need to look in the CU, and then to test at each outlet.

JohnD · 10 Jul 2021

Tactical DIY said:
The cable is 6243Y 3x1.5+1

that's lighting cable, not for sockets.

Tactical DIY · 10 Jul 2021

JohnD said:
might have been wired by an industrial electrician who stole the cable from work.

Although there are conventions for colours, you can't be sure what he has done. You need to look in the CU, and then to test at each outlet.

That sounds very likely as the previous tenant worked as a spark at a factory.

I'll remove some further faceplates and see what he's done with them.

On speaking with the spark who connected my supply for an outside building, he said as long as you know what wire he hasn't used from the 3 (grey/brown/black) then I will know what he's used as the circuit/ring.

Does that make sense!?

EFLImpudence · 10 Jul 2021

JohnD said:
that's lighting cable, not for sockets.

No such thing.

1.5mm² T(hree)&E may be used for sockets and 1mm² T&E or smaller flex used for lights.

plugwash · 10 Jul 2021

So you are now saying the cable is 1.5mm² not 2.5mm², that is more believable (while 2.5mm² 3+E exists it's not exactly common).

It's not wrong per-se to use 3+E and leave a core unused or doubled-up, but the use of a cable that would normally be used for lighting on socket circuits raises questions of whether there is adequate over current protection. You really need to fully investigate the situation before you can make a plan on how to go forward.

What terminals are the wires connected to in the existing sockets? is there any tape or sleeving applied to identify the conductors? is the use of the colors consistent throughout the circuit?

What fuse or breaker are these sockets fed from?

Is the 3+E present throughout the whole circuit or just for part of it?

Tactical DIY · 10 Jul 2021

plugwash said:
So you are now saying the cable is 1.5mm² not 2.5mm², that is more believable (while 2.5mm² 3+E exists it's not exactly common).

It's not wrong per-se to use 3+E and leave a core unused or doubled-up, but the use of a cable that would normally be used for lighting on socket circuits raises questions of whether there is adequate over current protection. You really need to fully investigate the situation before you can make a plan on how to go forward.

What terminals are the wires connected to in the existing sockets? is there any tape or sleeving applied to identify the conductors? is the use of the colors consistent throughout the circuit?

What fuse or breaker are these sockets fed from?

Is the 3+E present throughout the whole circuit or just for part of it?

That was my mistake with the 2.5. Fat fingers.
It is 1.5.
When I'm back tomorrow I'll check what terminals are used for the relevant colours and let you all know.
I'll also check the breaker, but I'm sure it is a 16a.

Astra99 · 10 Jul 2021

1.5mm² T(hree) & E is rated at 20A clipped direct, so IF the circuit breaker is rated at 16A, there is nothing to prevent 1.5mm² being used for a radial socket circuit, is there?

EFLImpudence · 10 Jul 2021

No, nor is there anything to prevent it being used on a 32A ring.

It satisfies the minimum CCC of 20A (if installation method appropriate).

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3 core and earth sockets

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