3 core twin and earth cable what colour should you use as the neutral

telectrix · Mar 5, 2011

we all know what we should do. pity the manufactures don't. if a simple patress can be made with a terminal for the cpc, why can't a fan. and why, when you bring your cable out for the fan on first fix, does the fan turn out to have the only possible cable entry on the other side of the hole.

malcolmsanford · Mar 5, 2011

keefy said:
You seemed to misread my post. I never said cost was relevant to the regulations, but GOOD working practices are relevant to cost. If you spend an extra 10 pence on cables to make a good job then surely that is 10p well spent?

As pointed out, the regulation states that you should not use green / yellow cables for anything else but earthing or bonding, period! Too many people I have been involved with in this industry agree with, or sometimes even influenced, my view on this one for me to start saving a few pennies.

If you are happy to install 2way lighting circuits with 3 core flex then carry on. You would not get away with that on one of my sites.

stop please quoting regs that you obviously no very litte about, your talking about bad practice or working practices, but not what the regulation says. You can not use the colour for any other purpose and you can not use a single core cable for anything other than an earth or bonding conductor, but the reg carries on to say even if you wanted to over mark that single, which leads onto the fact that in a multi-core cable you can over mark it, and use it as you wish.

I'm not happy to use it as strappers you asked to give examples and I did, I didn't say it is what should be done, but can be done.

keefy · Mar 5, 2011

malcolmsanford said:
stop please quoting regs that you obviously no very litte about, your talking about bad practice or working practices, but not what the regulation says. You can not use the colour for any other purpose and you can not use a single core cable for anything other than an earth or bonding conductor, but the reg carries on to say even if you wanted to over mark that single, which leads onto the fact that in a multi-core cable you can over mark it, and use it as you wish.

I'm not happy to use it as strappers you asked to give examples and I did, I didn't say it is what should be done, but can be done.

OK Malcolm you need to calm down a little. You rant on about me not knowing the regulations, but you know nothing of me or my history. I have done a bit of research and as stated before am not on my own when it comes to assuming the first paragraph refers to green / yellow, period and it seems the vast majority of posts say no it should not be done even if they see it as you have stated. However I do concede that once the regulation is studied and understood it can be explained thus:

A single conductor, in trunking say, cannot be used for anything but bonding or earthing due to the fact it may be easily accessible on its own under normal conditions (i.e. conduit box) whereas multicore cable is not as you need to cut it to access the cores. This would seem to lead to the possibility that you may cut the green yellow conductor in said conduit box when making an alteration assuming it was not live as you have isolated only one circuit within the conduit system. This would not be the case with a multicore as you would isolate the whole cable (537.2 refers). Although this is a bit of a revelation for me, knowing where I got my belief from has not changed my opinion on the practice.

It won't be the first time I disagree with the regulations on a safety aspect as I still believe it is not good to use green yellow cores for anything other than earthing or bonding, and that is where I miss read it... and many people, as stated before, agree with me.

You stated that in some cases it maybe called for, but then reeled off dubious examples of where you can get away with it, central heating systems being the main one (bad pipe fitters wiring).

It seemed you had some moral crusade to wage on the use of green & yellow given you thought it was an OK practice, but neglected to consider the fact that you are in a minority, and the naughty electrician in the corner of the tea room.

adslev · Mar 5, 2011

wirepuller said:
I've been in the industry 30 yrs and am not averse to change....However this country has a long and distinguished tradition of implementing daft ideas....and harmonising cable colours has to be up there with the daftest.
Thanks to this piece of genius thinking we now have a situation where blacks and blues could be either phase or neutral...and drab dingy phase colours which are hard to tell apart in low light..and just to let everyone know how silly wev'e been we have to stick silly stickers over every DB pointing out our sillyness.
The UK is an island...there is no overlapping of wiring systems with our european masters...we didnt need to change.

The uk is an island? Ok I live in northern ireland, I have worked in the south of ireland for many years and believe or not they are part of europe so there was overlapping of wiring systems!

Inghamgarry · May 16, 2015

What is 3 core twin and earth cable. It is either 3 core cable, 3 core and earth or twin and earth

Sintra · May 16, 2015

Don't think it's going to matter now as this thread is over 4 years old and I'm sure the op has got his answer.

7029 dave · May 17, 2015

Inghamgarry said:
What is 3 core twin and earth cable. It is either 3 core cable, 3 core and earth or twin and earth

Or even tripple& earth.

Paul.M · May 17, 2015

This thread is that old the 3 core and earth is due it's first EICR lol

baldsparkies · May 18, 2015

We once covered a 6 year old install that had black brown grey wiring taped with red yellow and blue.
The guy had even gone to the trouble of providing a mixed wiring label at the board.
We had a chuckle I must admit.

SteveH40 · May 19, 2015

he'd covered all bases then!

Dan · Oct 4, 2016

Just bumping some threads in the Electrical Wiring Theories and Regulations forum category here on our Electricians Forums. If this specific topic isn't current, just ignore it, it'll drop off the list in no time. However, if it's something you'd like to contribute to, feel free to reply and bring it back into current discussion.