Wiring questions - installing new thermostat

[doitall]

Just to conclude, all the sparkies that should know better.

Over sleeving a green and yellow core for heating controls is approved and exceptable by the NICEIC, and Building control, still waiting for NAPIT reply.

Can't wait for the sparks to get home, especially BAS

 

[Spark123]

Exceptable or acceptable??

 

[doitall]

Exceptable or acceptable??

Can always tell when you are loosing the battle. BAS will be as abusive as ever just wait and see.

Napit agrees with the sparks so 2-1 in favour of the heating guys at the moment.

 

[Spark123]

I personally would not do this however there are times where it would be easier to oversleeve an insulated sheathed green/yellow conductor for use as a live.
It is a question of wether or not green/yellow should ever be used for something other than a protective conductor given that it is green/yellow throughout it's length. Most sparks like to think that as a green and yellow it should never be used for anything else which is basically back to our training all those years ago!!

 

[doitall]

Agreed, it's like asking a 100 RGIs a question and you'll get a dozen different answers.

What does it say in the book about using pink, mauve, sky blue pink and a load of wire with different colored stripes down them.

We used to use at least 30 different colours in the control panels

 

[Spark123]

I'm used to that sort of stuff too, the fact is the current edition of the regs (17th edn BS7671:2008 amd 2011) causes some confustion on the matter by mentioning single core conductors.
Prior editions such as the 16th edn (i.e. this scan from the amd 2 of the 1992 regs - yellow cover) made it cast in stone back then that you must never use green/yellow for any other purpose:

Untitled

• Spark123
• 4 Jan 2013
• 2

 

[doitall]

But didn't that change with the Europe directive and harmonisation.

 

[Spark123]

Possibly, however it is something that was drummed into every electrician who was trained in the 16th era which there are still a lot of about!
The punishment for falling foul of it was a megger across the back of the neck

 

[mfarrow]

The current version of BS 7671 uses pretty much the same wording, regarding green/yellow colours.

One can speculate on the purpose of that particular mention, but in reality all we need to know is that the colours are reserved for cpc usage, and for anything else in an electrical installation, we must use another colour. To waiver on the side of caution in this case, I'd probably sheath the entire exposed length.

 

[doitall]

You saying that, there's nothing in the 17th.

I wouldn't use the green and yellow as a phase wire, oversleeved or not, but thats not the point.

 

[doitall]

To waiver on the side of caution in this case, I'd probably sheath the entire exposed length.

Get away if you gonna do that you may as well change the wire for another colour, like yellow or black.

Or do you mean the little bit on the ends.

 

[ericmark]

514.4.2 Protective conductor
The bi-colour combination green-and-yellow shall be used exclusively for identification of a protective conductor and this combination shall not be used for any other purpose.

How can anyone argue about that? It is rather final. It continues:-

Single-core cables that are coloured green-and-yellow throughout their length shall only be used as a protective conductor and shall not be over-marked at their terminations, except as permitted by Regulation 514.4.3.
In this combination one of the colours shall cover at least 30 % and at most 70 % of the surface being coloured, while the other colour shall cover the remainder of the surface.
A bare conductor or busbar used as a protective conductor shall be identified. where necessary, by equal green-and yellow stripes, each not less than 15 mm and not more than 100 mm wide, close together, either throughout the length of the conductor or in each compartment and unit and at each accessible position. If adhesive tape is used, it shall be bi-coloured.

The exception referred to is for a PEN conductor which are never used within the home.

Persimmon Homes had a site just outside Liverpool where the green/yellow had been used as line wiring the tank thermostat must be about 15 years back now and the electrical firm was dismissed over it. As far as I am aware the fault was not corrected so yes one can come across cases where it has been done.

Before that there was a court case where some electrician had placed a lose green wire onto a multi-spade earth terminal it would seem thinking it was an earth wire but it was the normally closed terminal of the main switch so when the heating was switched off it made the case line.

Because he had turned everything on to test this error was missed. It would seem had the occupier been killed straight away then the electrician may have got away with it. However he was called back with reports of getting shocks and still missed finding the fault.

He had a prison sentence as a result. During the summing up there were many points made and I am lead to believe 514.4.5 The single colour green shall not be used. Was one of the results of the court case.

The lack of earth wires was not due to the en-prisoned electricians actions but it was stated as the last person working on the system he should have either corrected the lack of earthing or refused to activate the appliance. It was it seems just plugged in.

I wish I still had the college notes as this was the case sited to us and it was emphasised over and over again to fit a plug on an item in a shop is OK but doing the same job in the home we must test the socket it is being plugged into. Many firms of the day issued the old plug in Martindale tester as a result.

This was all likely 40 years ago or more but like the case of the baby dyeing due to a plastic hot water tank failure it was repeated again and again.

To use green/yellow cable for anything other than earth or a PEN conductor (with blue sleeve) is asking to be detained at her majesties pleasure.

 

[doitall]

What does exemptions in the IEE regulations say.

And as for the nice story, 100% the sparks fault.

 

[matt1e]

mmm interesting thread and I have to admit that at the begining I would have argued the sparkies point
I would never use or condone the use of an earth wire for anything other than earth
But I've got to admit I can find nothing to dispute DIA's argument
(I wish I could, honest) though I can with the other side of it

Prior editions such as the 16th edn (i.e. this scan from the amd 2 of the 1992 regs - yellow cover) made it cast in stone back then that you must never use green/yellow for any other purpose:

Untitled

• Spark123
• 4 Jan 2013
• 2

that scan means exactly what erics quote from the 17th means and its not what you think see below

514.4.2 Protective conductor
The bi-colour combination green-and-yellow shall be used exclusively for identification of a protective conductor and this combination shall not be used for any other purpose.

How can anyone argue about that? It is rather final.

but it's not saying what you think it does
It's saying that a cable identified by the Bi colour combination green and yellow will be a protective conductor and nothing else
It does not say that you can not over sleeve said conductor and use it for a live conductor
then we have

Single-core cables that are coloured green-and-yellow throughout their length shall only be used as a protective conductor and shall not be over-marked at their terminations, except as permitted by Regulation 514.4.3.
In this combination one of the colours shall cover at least 30 % and at most 70 % of the surface being coloured, while the other colour shall cover the remainder of the surface.

A reference to single core cables not multicore

Persimmon Homes had a site just outside Liverpool where the green/yellow had been used as line wiring the tank thermostat must be about 15 years back now and the electrical firm was dismissed over it. As far as I am aware the fault was not corrected so yes one can come across cases where it has been done.

and did they oversleeve the core, or just leave it plain old green/yellow

Before that there was a court case where some electrician had placed a lose green wire onto a multi-spade earth terminal etc etc

irrelevant to this thread

This was all likely 40 years ago or more but like the case of the baby dyeing due to a plastic hot water tank failure it was repeated again and again..

again irrelevant to this thread
Hey I'll admit I've been wrong all these years if need be, I await doitalls replies to his emails with interest. and if he is proved to be correct then you just need to get over it
An apology to him should be on the cards too

one thing puzzles me though, and it's probably one for the sparkies to answer
in the same scenario ie a cylinder stat has been wired using 3core flex
and the earth conductor has been over sleeved and used as a live.
I thought these days earth cables had to be ran in and connected through anyway even to double insulated accessories

Matt

 

[doitall]

Matt,

I'm not looking for anything.

Over the years I have seen thousands, all approved and passed by bodies they should, one assumes know.

Lateral thinking says they would have failed if it was not acceptable.

NICEIC said it is ok, I haven't heard from John at Napit, but some guy email to say no it wasn't, we shall have to see what if anyone else replies.

I think it's a great discussion and clearly quite important as far as the htg guys are concerned.

My gut feeling says it's normal practice and acceptable.