Wiring a PIR

[bongos]

Ah, that's the big question. I'm now coming around to see that 2 of the wires are + & - supply and the 3rd one is the switched feed to the lamp, which I'm guessing has its own + & - supplies?

I think you're getting yourself mixed up with DC voltage here. Your house has AC.

You have brown/black/grey and an earth supplied from somewhere in your house. These should have been correctly sleeved to identify line and neutral cores by the person who installed the original light but it seems that they haven't bothered. You will need to find the other end of this cable where it goes to a light switch/FCU and take a photo of what you have there.

It is common to have brown as permanent live, black as switched live and grey as neutral but you must confirm this is the case before connecting up your new light.

Find that switch!

 

[Tallyman]

Thanks again. When I referred to + & - it was just shorthand for live & neutral. Anyway, I'm leaving it til after the bank holiday so I can start getting into roofspaces (it's the gable end of a bungalow) & trace/replace the wire(s). At least I now know what the wires are each for - even contacted the manufacturer's helpline who admitted they could have been clearer about connecting to the L1 terminal - it's not mentioned at all! So thanks again for all input (no pun intended!)