Should have checked what went where before taking off....

[DoubleAgent]

'Lo folks

Took a crappy old light fitting off and replaced it with a nice shiny new one... what I didn't do is check what wire went where before I took it off

It seems I have 2 live and 2 neutral coming out of the ceiling instead of one of each as is the case in every light fitting upstairs (Trust me to screw up this one!)

In my new fitting I've got room for....

2 x live
3 x neutral
3 x loop

The old fitting was 2 x live, neutral and loop each

I can't put the lives together as it just trips, if I put a live in the loop all works ok but the light switch won't turn the light off, I'm presuming that live and neutral wouldn't go together in the loop as that would equal either a bang or a trip which I'm not going to attempt.....

Anyone got any ideas ?

 

[RF Lighting]

//www.diynot.com/wiki/electrics:lighting:problems:blackswlive

 

[rebuke]

I would suspect what you have is one cable that is the supply (i.e. permanently live), and one that runs to the switch. This means that one of the blacks is not a neutral, but instead is a switched live - in theory this should be indicated by some red/brown tape/sleeving, however unfortunately this isn't always done...

If you have a multimeter, then with the power off meter between the red and black on each cable, you should find the switch line has a very low resistance when the switch is on, and infinite resistance when the switch is off - the supply cable should always read the same (it will have a resistance as if any light switches are still on you'll get one across the bulbs)...