Roger Mills wrote:
In an earlier contribution to this discussion,
Golan wrote:

I want to move my room thermostat from the bedroom to the hall. What
kind of wire do I need to buy? What is the thickness?

It depends on what it's switching!

If it is a conventional gas or oil fired CH system, it will only take about
3 amps total for boiler control, pump and motorised valves - in which case 1
mm^2 cable is more than adequate.

3 amps ?!? My honeywell wiring centre came fused for 2 ..