type of wires for central heating components?

[stevehayes]

just a brief question about central heating wires:

i know a motorized valve uses a 5-core wire. and an immersion heater uses a 2.5mm2 heat resistant flex. but what wires and used for cylinder stats, room stats, pumps, etc? just normal 3 core? any specific size or features?

 

[D_Hailsham]

what wires and used for cylinder stats, room stats, pumps, etc? just normal 3 core? any specific size or features?

NEVER use the yellow/green earth wire as a voltage carrying wire.

Cylinder stats will require a two (S Plan) or three core (Y plan) plus earth, though the earth may not be used.

Rooms stats (not programmers) are the same as cylinder stats.

Programmers may require a 4 core plus earth.

If the blue (neutral wire) is used to carry voltage it should have red tape round the end or a red sleeve.

You can get all the wires from B & Q

 

[stevehayes]

ok thanks for your help! i know on a cylinder stat there are 3 wires used. and they connect up on the stat to C, 1 & 2. if using a brand new wire to connect up the stat and not the original wire is there any colour code that should be used, ie brown for C terminal??!

 

[AlanE]

... red tape round the end or a red sleeve

Brown sleeve now!

 

[D_Hailsham]

is there any colour code that should be used, ie brown for C terminal??!

I don't know of one. Make up your own and be consistent.

Brown sleeve now!

Thanks for the info; that's news to me. When was it changed?

 

[stevehayes]

ok so for example as long as the wires all link up together in the terminal box in the correct way it doesn't matter what colour you use? except obviously for earth!!

thanks a lot for your help.

 

[D_Hailsham]

as long as the wires all link up together in the terminal box in the correct way it doesn't matter what colour you use?

Correct!

As for colours, the only suggestion I would make is that the brown wire should be used to indicate the un-switched live; e.g. from the wiring centre to the C terminal of the HW stat and similarly for the wire to the thermostat. Obviously the correct colours must be used for the supply to the pump, motorized valve and boiler.

 

[gas4you]

When was it changed?

Jan 1st this year I believe was the official start date when red should no longer be used.

 

[stevehayes]

that's a good point-the pump has a 3-core wire too, so are these all standard colour coded wires that come with a new pump?!

 

[D_Hailsham]

that's a good point-the pump has a 3-core wire too, so are these all standard colour coded wires that come with a new pump?!

It does not matter if the pump comes with a three core or you have to provide one, the correct wiring is: Live=Brown; Neutral=Blue; Earth=Green/Yellow.

 

[stevehayes]

of course!! sorry for the stupid question!!! was just curious!!

 

[baxpoti]

... red tape round the end or a red sleeve

Brown sleeve now!

Or marked 'L' (Line)

as per
BS7671:2008 IEE Wiring Regulations 17th Edition Appendix 7 Chapter 3 page 343.

 

[simond]

You can use the green cable in a flexible sheated cable product for phases providing you clearly identify the fact at both ends, eg: brown or blue markers.

I don't consider it best practice, but it is acceptable. Haven't read 17th edition yet.

 

[baxpoti]

You can use the green cable in a flexible sheated cable product for phases providing you clearly identify the fact at both ends, eg: brown or blue markers.

No you can't!


BS7671:2008 Regulation 514.4.2 states
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.

 

[simond]

That was in the 15th edition, never mind the 17th.

However, you are misinterpreting it. Providing both ends are clearly labelled as phase conductors, and it is insulated and sheathed (eg: not the earth out of a twin&e domestic cable) it is acceptable.

Unless there is a specific new line other than the one you list.