Line voltage wall thermostat wiring.

[johnnyuk]

Hi all

I'm in the process of replacing some 1970s underfloor heating line voltage sauter wall thermostats with new mechanical replacements (of which there seem to be incredibly few in existence - sauter were very unhelpful with suggestions!).

Anyway I have found a replacement (T4360B1015 for interest), but had a question about wiring.

There is only a single 2.5mm twin and earth wired into the back of the original thermostats. CPC is obviously just CPC, but the other two cores are unmarked - one is black and one is red (1970s colouring).

Aren't these really line and switched line? ie shouldn't the black wire be sleeved red to indicate it's switched live? Or is it possible that these wires are genuinely line and neutral?

Sorry if that is a dumb question.

 

[brianmoooore]

If it's a single T&E to an old mechanical 'stat, then it'll be live and switched live. Sleeving wires of the wrong colour was unheard of in 1970 (when I started). The thinking then was that if you were too stupid to realise that the black was a switched live, then you probably shouldn't be touching things anyway. Darwin's law was big back then.

 

[johnnyuk]

If it's a single T&E to an old mechanical 'stat, then it'll be live and switched live. Sleeving wires of the wrong colour was unheard of in 1970 (when I started). The thinking then was that if you were too stupid to realise that the black was a switched live, then you probably shouldn't be touching things anyway. Darwin's law was big back then.

Brilliant. Thanks Brian much appreciate the advice.