light permanently on

mikesimm · Posted: Wed Aug 16, 2006 6:58 pm Post Subject: light permanently on

Hi In my son's room he had an old 3 light ceiling spot light. One of the bulbs literally blew out of the holder and although I tried to replace it one of the three lights won't work - so as it was 20 years old, I bought a new 4 light spotlight. I wired the old red fron the ceiling into the brown of the light, then the old black from the ceiling to the blue of the light, then attached the earth to the earth on the light. When I switch the power back on, with the light switch off, the light comes on. When I try to switch the light switch on, the fuse blows. There are no visible wires touching. Any ideas ?

fireman22 · Posted: Wed Aug 16, 2006 7:04 pm Post Subject:

did you only have one cable coming out of the ceiling (red black and earth)

mikesimm · Posted: Wed Aug 16, 2006 7:10 pm Post Subject:

No - I had three reds all twisted together, three blacks twisted together and 2 earths twisted together.

Each of the three colours go into separate plastic junction boxes.

fireman22 · Posted: Wed Aug 16, 2006 7:12 pm Post Subject:

no, bet you didnt, are you 100% thats how it was. usually all blacks together two of the red's together on red on its own with the live and neutral of your light fitting into blacks and the red on its own

fireman22 · Posted: Wed Aug 16, 2006 7:14 pm Post Subject:

one red on its own

mikesimm · Posted: Wed Aug 16, 2006 7:20 pm Post Subject:

I'm not 100% sure. Just say a little more about your last post as I reckon it must be that.

Any way I can tell which red is on its own (or doesn't it matter). It would help me if you could clarify, from the wires down from the ceiling, how they should be combined. Really appreciate your help.

fireman22 · Posted: Wed Aug 16, 2006 7:20 pm Post Subject:

sorry mike one eye on football didnt quite read your post correctly,
all reds together two blacks together with neutral of your light fitting with other black to live of your light fitting (you should wrap some red tape around this to show it is the switched live return. when you are switching the wall switch you are putting a dead short accross live and neutral. you may have blown the switch and it may now require replacing

fireman22 · Posted: Wed Aug 16, 2006 7:22 pm Post Subject:

if you look in the refence section (third one down ) scroll down to see pic

fireman22 · Posted: Wed Aug 16, 2006 7:26 pm Post Subject:

you need to identify which is the cable going to the wall switch, if you can get above you may be able to trace it

mikesimm · Posted: Wed Aug 16, 2006 7:27 pm Post Subject:

one eye on the football here too. Crouch should have scored. So I have five wires (three reds and two blacks) to neutral and the other black to the live of the light fitting.

If I understand you right, does it matter which black ?

fireman22 · Posted: Wed Aug 16, 2006 7:32 pm Post Subject:

mike sorry no, three reds together in a connector block, two blacks in a connector block with the neutral of the light fitting and the last black in a connector block with the live of the light fitting. yes the single black must be the black of the cable going to the wall switch ( you should wrap some red tape around it to show it is the switched live return)

mikesimm · Posted: Wed Aug 16, 2006 7:35 pm Post Subject:

thats brilliant thanks - its too dark to work on now so I'll do it in the morning. Thanks a million for your help. Hope england win. If you have sky - Murray's beating Federer.

fireman22 · Posted: Wed Aug 16, 2006 7:36 pm Post Subject:

no worries
paul

mikesimm · Posted: Wed Aug 16, 2006 7:39 pm Post Subject:

sorry Paul - one last thing - the three reds in a connector block - nothing from the light attached to it ?

fender · Posted: Wed Aug 16, 2006 9:15 pm Post Subject:

Try this..

Switch off lighting circuit. ( at the main board )

Separate all the blacks and make sure they are not touching anything or each other.

Turn power back on and see which black goes live / dead as you turn the light switch on and off. The one that does, connect to the live of your light. Put the other blacks back where they were and connect the N of your light to them.

The above assumes you have a mains tester....