al wrote:

AFAIK, you shouldn't use the lighting circuit at all, as even if you don't,
a future person could attach something of high load and cause a fire.

Strangely.... When we re-wired our on-going project, there was a 2KW
electric fan in the bathroom wired from the lighting circuit.

Only initially realised this when all the downstairs (Bedroom/bathroom)
lights were on and I flicked the heater on full.

When we had an electrician round to quote on re-wiring I mentioned it
and he said it's not uncommon and he's even done it himself on occasions!

He didn't say how long ago mind.