2.5mm or 4mm T&E

Argyll · Post by **Argyll** » Sun Sep 12, 2021 4:36 pm

I'm just about to run rewire my kitchen. I bought a couple of reels of 2.5mm T&E a couple of years ago. I read the norm now is 4mm T&E. Is this correct?

I don't want to run 2.5mm only for the electrician to refuse to make the final connection and sign off as it's 2.5mm T&E.

Neelix · Post by **Neelix** » Sun Sep 12, 2021 5:58 pm

You could use either BUT do find a spark before you start because most of us won’t touch DIY installs

Argyll · Post by **Argyll** » Sun Sep 12, 2021 11:34 pm

I'm stripping it all down to the bare brick mate so I'll get him in to inspect it before I dot and dab.

Good to know I can still use 2.5mm

ericmark · Post by **ericmark** » Mon Sep 13, 2021 8:09 pm

There are three things which mean a ring final needs 4mm cable, one going through insulation, two the earth loop impedance will not be low enough for the trip size, and three the line - neutral loop impedance is not low enough for volt drop.

The other is when radials are used.

There can be three signatures on an installation certificate, one for design, one for installation, and one for inspection and testing, however as far as I am aware there are no longer any scheme providers who permit their members to do third party testing. The English Part P law allows it, but not the Welsh one, but the scheme providers it seems did not like the idea, so would not permit it.

Scotland completely diffrent again.

It seems some scheme providers did for a time allow it, but seems now down to two, has to be two or it would break the closed shop rule and scheme providers would become illegal.

No one really cares if work is registered unless something goes wrong, and if something does go wrong, an electrician breaking the rules will be caught out, so seems little point breaking the rules.

Argyll · Post by **Argyll** » Wed Sep 15, 2021 5:54 pm

It'll be a ring circuit. My pals a sparky so I'll get him to check it albeit I think he's 12th edition.

Neelix · Post by **Neelix** » Wed Sep 15, 2021 9:50 pm

Wow, 12th edition. How old is he?

ericmark · Post by **ericmark** » Wed Sep 22, 2021 2:13 am

Neelix wrote: ↑Wed Sep 15, 2021 9:50 pm Wow, 12th edition. How old is he?

Trading 1950 to 1954 at that time 7 year apprenticeship so would need to be born 1930''s. I would say likely 12th edition is when the ring final started?

Argyll · Post by **Argyll** » Wed Sep 22, 2021 2:17 pm

Maybe it's later than that then. he's around his early 60's.

Someone-Else · Post by **Someone-Else** » Wed Sep 22, 2021 3:13 pm

12th Edition came out before he was born, I guess he would be 14th or 15th edition.

Bob225 · Post by **Bob225** » Wed Sep 22, 2021 5:01 pm

2.5 is fine for a ring plus you will never get 2x 4mm into a double socket without a fight and/or a deep pattress, iirc 2.5 has a drop of 15mv per meter

12th edition is 1950, so he may even be 11th ed.

Neelix · Post by **Neelix** » Wed Sep 22, 2021 7:30 pm

Bob225 wrote: ↑Wed Sep 22, 2021 5:01 pm 2.5 is fine for a ring plus you will never get 2x 4mm into a double socket without a fight and/or a deep pattress, iirc 2.5 has a drop of 15mv per meter

12th edition is 1950, so he may even be 11th ed.

I have to disagree with this - it depends on whose accessories you are using.