Lethal is the word I would use.

Yes, if it has to be taken from a ring as a spur, take using 2.5 T/E  to an FCU (Fuse Control Unit) then using 1.0 or 1.5 T/E to PIR light WITH cpc (earth). Ya can of course take to a non-switched FCU then onto the switch then onto the PIR if ya want to.

I have yet to come across a PIR light that is Class II (no earth required) but I stand to be told of one, if it has a square within a square symbol on it then it is Class II else it is Calls I and an EARTH is required.

RR

I'm still in the process of trying to sort out minor niggles in my mother's house...

I recently changed the PIR light outside as the glass had broken and the switch was in a stupid position - in the "guest beddroom" and blocked by wardrobe. I got round to removing the old installation yesterday and was quite surprised at what I found. The power to the light was supplied from the back of a double socket and was in 2 core cable. That cable was loose and want under the carpet before going up a wall where it joined the light switch. From there, the wire to the light was 1mm twin and earth. Was this safe?  I can for example see an idiot DIYer like me assuming that the earth on that cable as being an earth when in reality it wasn't connected to anything... The main reason for asking is that light was fitted at the same time as my mother had all the wiring checked and redone when she moved in.

I'd also like to ask about what I've done with the new light. I've run it to a socket but have wired the last bit on flexible cable and fitted a plug with a 3A fuse. Is that OK?  And as well, I wired that to a 5A junction box and from there on ran in 1mm 3 core & earth to make it easy for me to have a "courtesy light" in the porch. It runs R = Live, Blue=Neutral and Yellow=Switched Live from the PIR. It works well but is it allowed?