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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> which cable https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1100727958 Message started by reg on Nov 17^th, 2004, 9:45pm

Title: which cable
Post by reg on Nov 17^th, 2004, 9:45pm

I want to replace a pendant light with a track holding 4 halogen lights. It is the last light in a loop in circuit so there are only two cables visable, each with a red and black wire and no earths. I understand one of these cables is the circuit and the other is to the light switch and should be marked as such, but neither has any identification at all. Is there a simple foolproof method to establish which cable is to the light switch? Any hints would be very welcome.

Title: Re: which cable
Post by plugwash on Nov 17^th, 2004, 9:52pm

some of the sparkys here will probablly hate me for syaing this but it really doesn't matter much

if you get the two blacks the wrong way round in the fitting its not doing to break anything or make it dangerous

Title: Re: which cable
Post by supersparky on Nov 17^th, 2004, 10:04pm

if you have a continuety tester, or a torch that will do

kill the power at the fuse board
use the main switch unless you have a meter that you can be sure of telling you its dead(test it on a known live source to prove the unit - you should make sure you have only one main switch and there arnt any hiding)

then get the two cables, seperate their cores out
connect your meter (or between the battery and the bulb if your using a torch) and operate/ get somone to operate the switch.
if the meter shows continuity when the switch is operated, and then dies when its disconnected then thats the cable.

ss

Title: Re: which cable
Post by ban-all-sheds on Nov 18^th, 2004, 9:48am

I wouldn't bother with testing, unless you want to rectify the unmarked-switched-live problem.

Use a junction box, connect the two reds together, keep the blacks separate, wire the track to the two blacks.

I'd be more concerned about the lack of earth - is it just here, or does none of the lighting circuit have an earth?

Does this track require an earth?

Do you have any other lights which need an earth?

Do you have metal switches?

Title: Re: which cable
Post by reg on Nov 19^th, 2004, 12:05am

The light circuit has no earth afraid to say. The house was built around 40 years ago and still has the original wiring. All the light fittings are plastic as is the new track which does not have an earth. Thanks to all you guys for your input which has helped me get the job done

Title: Re: which cable
Post by ban-all-sheds on Nov 19^th, 2004, 12:34am

wrote on Nov 19^th, 2004, 12:05am:

The house was built around 40 years ago and still has the original wiring.

If that's true, you might be due for a rewire...