DIY Doctor

ceiling lighting

Postby intrinseca » Sat Jan 05, 2008 5:34 pm

i have a new ceiling light to fit,have taken old ceiling rose down it has 4 cables (containing (4 reds 4 blacks 4 earth) new light has block with earth live neutral loop when i connect wires one way lights will not switch off another way will not switch on please help
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Simply Build It

Postby thedoctor » Sat Jan 05, 2008 5:40 pm

There is a project in the projects section callled replacing a light fitting and the same question has been asked and answered at least 20 times in this forum, please search for the answer or view the project.
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Postby ericmark » Mon Jan 07, 2008 8:09 am

The count seems wrong normally three cables not four. I will guess
Feed in.
Feed out1.
Feed out2.
You need to identify the switch cable as this one will NOT have the black/blue connected to rest doing so would make a direct short. It should have a sleeve on it.
Easy bit first, All earths together (Should have Green/Yellow sleeve on them) This includes new lamp, and all lives together (either red or brown) not new lamp.
You now have four black or blue wires left. The problem one is live and other three are neutral. If you still have the sleeve no problem. One with sleeve goes to new lamp live and other three to new lamp return/neutral.
Otherwise its a long job to work it out. Really best to get electrician if unmarked but I know most people will try so if I didn't have my meter I would use lamp its self. Using a spare block connector for all unconnected wires so they can't touch each other or anything else and switching off power between each test I would start by connecting live to all the reds/brown on temporary basis. Then try all the blacks/blues on lamp until it works should only be one. This is neutral feed so now I would disconnect lamp from reds/brown and connect the blue to the black/blue identified as return/neutral. Now each one of the blacks/blues need to be connected to the brown on new lamp. If all other lights are off only one will work light when switch is used. But if any other lamps are on then some will work dim and one will work correct. Best idea to ensure they are off is to remove bulbs and do make sure there are no energy saving bulbs in the lamps both new and existing in other rooms. Once you are sure you have found switch wire and only when you are 100% sure then all other black/blues go together and switch wire goes to new lamp brown.
An electrician would use his meter and would find the switch wire without needing the power on and it would be a lot easier and safer to get an electrician to do the job. Especially since you have four cables instead of normal three I have assumed the extra one feeds a second lamp off that rose but it could be another switch which would really mess things up. So unless the cables are marked as to which is switch wire I would recommend an electrician. Even if it is marked you should really get it done by an electrician who would normally check the system when complete and fill in a minor works cert to ensure the system is safe. i.e. that those earths are really connected. [/i]

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