spotlight/loop-in problem

[mikk]

Attempting to replace single ceiling light with spotlights (single fitting)Many hours and swear words later it is working (switching on) but not completely off! The lights are still recieving some current because they are still on (though dim)even when the switch is in the off position?? I have connected the 3 lives together, the 2 neutrals to the neutral terminal in the lamp, the swith wire to the brown lamp terminal and all 3 earth wires together whichs run through the terminal block and then screws to the metal bracket. HELP please.

 

[mapj1]

Most likely you have misidentified the switch wires, and it is in series with another fitting. I assume these are filament lamps, not compact fluroescents that can ghost strike off a very small leakages.
Is it one of the configurations in the 'for reference' sections?
If you have a meter you can verify this is true or not.

 

[felix]

Most likely you have misidentified the switch wires, and it is in series with another fitting.

I agree that this is the most likely cause. Assuming that all colours were correct in the first place (a rather bold assumption) you might have done this:

The brown wire on your light is connected to neutral form the fuse box, not switched live.

The blue wire on your light is connected to switched live AND neutral from one or more other lights.

This scenario will give exactly the symptoms you describe plus one more; those other lights will not work if your new light is switched on.

There are three ways of choosing two black (or are yours blue?) wires out of the three available. One is correct, another is (I think) what you've done and the third will put your switch straight across the supply! Start by confirming the swapped wire theory. Look for something that unexpectedly goes off when you switch your new light on.

 

[mikk]

Thanks guys, I think you are right. I tested all three cables across the red and blacks.Only one was live so I (wrongly) concluded that this must be the sw, but the wall switch didnt turn it off, it was live all the time (this should have told me!). I guess all I've done is identify the live feed. I will try swapping around one of the other black 'neutrals'. I will have a 50/50 chance of picking the sw 1st time. will let you know. M.

 

[felix]

You also have a 50/50 chance of connected the switch straight across the supply! Tread carefully because sparks will fly if you switch it on in this state. When my father did this many years ago he blew the electricity board fuse.

 

[mikk]

These MCB's are marvellous things (especially for screwdriver terrorists like me!) It fought me to the very last but I got it right in the end - thanks for your very quick and concise help. Nice Forum.