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Only 3 wires in light fitting - it doesn't work.

Posted: Fri Jun 15, 2007 1:58 pm
by Howard Hughes
I am changing a light fitting in my son's bedroom and there are only 3 wirse coming out of the ceiling; 1 black, 1 red and 1 without any trunking on it -which I presume is the earth. Connecting red and black to the live and neutral wires on the fitting and the earth to the appropriate terminal - the light doesn't work! Tried changing the bulb etc but no luck - the black wire is live as I've tried it with a current detector. Any ideas how I should wire this up to make it work??? Thanks

Re: Only 3 wires in light fitting - it doesn't work.

Posted: Fri Jun 15, 2007 7:25 pm
by BLAKEY1963
[quote="Howard Hughes"]I am changing a light fitting in my son's bedroom and there are only 3 wirse coming out of the ceiling; 1 black, 1 red and 1 without any trunking on it -which I presume is the earth. Connecting red and black to the live and neutral wires on the fitting and the earth to the appropriate terminal - the light doesn't work! Tried changing the bulb etc but no luck - the black wire is live as I've tried it with a current detector. Any ideas how I should wire this up to make it work??? Thanks[/quote] .

HOWARD
DO WE ASSUME EVERTHING WORKED BEFORE YOU TOOK THIS
LIGHT FITTING DOWN TO CHANGE IT. AND YOU HAVE NOT CHANGED ANY
OTHER LIGHT ?.
IF AS U SAY YOUR BLACK WIRE IS LIVE , IS THERE ANY INDICATION
OF A LIVE CONDITION WITH YOUR CURRENT DETECTOR ON THE
RED WIRE.
IF NOT IT IS POSSIBLE THAT YOUR COLOURS ARE MIXED UP WITH THE
BLACK CONNECTED TO PHASE AND THE RED BEING THE NEUTRAL.
I WOULD ADVISE YOU GETTING AN ELECTRICIAN IN TO CHECK FOR
CORRECT POLARITY WITH YOUR PHASE CONDUCTORS, AND ALSO
CHECK THAT YOUR NEUTRAL CONNECTION , IS CONTINOUS FROM THAT
FITTING , NORMALLY THE BLACK WIRE BACK TO THE NEUTRAL BAR AT
THE MAINS BOARD.
HAVE YOU ISOLATED SUPPLY AND CHECKED SWITCH WIRES IN SWITCH
IF SO , THEN YOU WOULD NEED EXPERT ADVICE

BLAKEY1963

Posted: Sat Jun 16, 2007 9:50 am
by diydoctor
The blackk wire is probably a switched live wire. Please see our project on replacing a light fitting.