Wired programmable stat cabling specs

[originalracingsnake]

I'm going to fit a Honeywell wired programmer stat to replace the rubbish wireless programmer and stat the boiler came with.

It is a WB Junior combi boiler.

To minimise the amount of channeling in the wall I have to do (it is a 60's build and uses concrete blocks!), what is minimum spec of cable I can use from boiler to control? Twin and Earth seems a bit overkill as the cable only carries a switching voltage/current (or does it?).

Any advice gratefully received.

 

[flameport]

The minimum is 2 cores, so T&E - however this is the absolute minimum and will require you use a battery operated thermostat, or an entirely mechanical one.

A far better choice would be 3 core & earth, which then allows the use of a mains powered stat (line, switched line & neutral).

 

[originalracingsnake]

Twin AND earth is 3 wires, surely?

I am after a cabling spec minimum. I.E., you can use bell wire, or flat speaker cable, or the cable carries 5 amps so it has to be lighting circuit spec.

I thought it was only a switching voltage and current, <2amps and 240v. The ad says it is a 2 wire connection...

http://tinyurl.com/ctznm6z

1.0mm-2.5mm2

1.0mm is less than lighting T&E, what is useable?

 

[flameport]

T&E has 3 wires, but as one of them is the earth, that only leaves 2 for your thermostat.
The wiring must be mains rated, so bell wire, speaker wire and similar is totally unsuitable.

That particular thermostat only requires 2 wires, however plenty of others require 3. The cable in the wall will be there far longer than that thermostat will.
The difference in width between T&E and 3C&E is about 2mm - which will make no difference to the size of the chase at all.

1.0mm is less than lighting T&E, what is useable?

No idea what you mean by 'lighting T&E'.

The correct cable to use is 3C&E 1.0mm cable. It's about 10mm wide.

 

[Dan Robinson]

0.75mm I thought?

 

[originalracingsnake]

Excellent, thank you very much. By lighting T&E, I only meant the lesser spec T&E, rather than the 13 Amp ring main T&E cable.

Thanks again everyone.