wiring thermostat + earth

Most programmable thermostats are battery operated and only need a line feed in and switched output - ie no neutral. But it does no harm to use a triple and earth with the neutral made off safely. And as you say earth the box, although the thermostat itself doesn't need one.

If it's close enough to the boiler panel to use flex, any three core will do. But certainly 0.75mm will be ok. Use the brown for the live feed and the blue for the switched return, and sleeve the blue cable with brown (or red) sleeving.

At least he had the sense not to use the earth for anything other than its intended purpose. The OP cant be a plumber !

Dave

It is 240v and requires this supply. I've found 4 core x 1mm for 2 quid per metre

I want 8 metres, 16 quid - it is starting to add up. Thats about two hundred quid now on gas/water/electrical fittings. Still my thermostat is groovy!

Cheers all.

Mike W

Is it actually a programmable thermostat or a programmer for the central heating? It's just that the fuse for the central heating usually protects the thermostat, but would be mentioned in the main programmer instructions. And I've not come across a thermostat that requires 4 core plus earth. Programmers for the system do, though.

Yes it is a programmable thermostat, this is the only device to regulate heating (other than TRVs). No It is 4 core including earth. Since it is flex it is not 3 core + earth. All wiring is fed from the boiler. I'm hoping the output is fused. I'll go do some probing.

-- Mike W

The boiler circuit should be fed via an FCU, and that fuse should protect all the wiring.

Why of course. Fused spur off downstairs ring. I meant the 2A fuse on the boilers board.

-- Mike W

That fuse might be just to protect the boiler's PCB, etc. The wiring diagram should show if it's in the feed to external devices.