confused as to what wire is switched live


Postby Meeki » Wed Aug 20, 2008 5:04 pm

Hi, I have stupidly removed a ceiing light fitting and ceiling rose without marking the cables, in order to install a track light fitting. coming from the ceiling I have 3 cables each containing 1 red, 1 black and 1 earth wire

Having read previous articles on here of similar situations it would seem that I am thankfully not the only fool to have performed this and so I went out and bought a DI-LOG DL114 multi tester to be able to perform a continuity test on each pair of red and black wires to find the live neutral

however on performing the above test 1 pair of wires bleeps with the electrical power of when the light switch is turned on,this I assume is the switched live and therefore needs to connected to the live on the light fitting, 1 pair dosent bleep, which I assume identifies 1 of the neutral wires which needs to be connected to the neutral wire on the light fitting, however the other pair bleeps whether the light switch is on or off and that is where I am confused and unsure as to where to put this neutral wire

Any help would be greatly appreciated as what I thought would be a 5 minute job is now turning into a long distance operation

Regards


Meeki
Meeki
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Postby ericmark » Thu Aug 21, 2008 8:47 am

Looking at my diagram to how lights work http://www.ericmark.talktalk.net/lights.bmp the first lamp will emulate the one you are testing nicely.
Assuming fuse removed.
The feed wire would show as open circuit (No beep)
The switch wire would change according to switch position.
The the feed to other lamps would have no beep if other lights in house turned off but if any light is turned on then it will beep and it will be connected by the bulb.
If you did same test on a mid circuit lamp then either feed in or or feed out could cause beep.
But since we are connecting like to like for feed in and feed out this does not matter as long as switch wire is identified.
Thank you lucky stars it was not the bathroom with even more wires!
Does that help! Any comments welcome it may help me explain to others.
Eric
ericmark

Postby Meeki » Thu Aug 21, 2008 10:07 am

[quote="ericmark"]Looking at my diagram to how lights work http://www.ericmark.talktalk.net/lights.bmp the first lamp will emulate the one you are testing nicely.
Assuming fuse removed.
The feed wire would show as open circuit (No beep)
The switch wire would change according to switch position.
The the feed to other lamps would have no beep if other lights in house turned off but if any light is turned on then it will beep and it will be connected by the bulb.
If you did same test on a mid circuit lamp then either feed in or or feed out could cause beep.
But since we are connecting like to like for feed in and feed out this does not matter as long as switch wire is identified.
Thank you lucky stars it was not the bathroom with even more wires!
Does that help! Any comments welcome it may help me explain to others.
Eric[/quote]

Many thanks, having clarified which wire is switch wire ie:- the one that beeps according to switch position, on = beep, off = no beep,(with electrical mains off ) I have wired this opposite the live feed from the new light in the 3 way block provided with new light, put the other 2 neutrals, feed in and feed out, together, and wired these opposite the neutral feed from the new light , wired the earths similarly and put all 3 reds from the ceiling into a block on their own and hooray we have light upstairs in the house again after a night of darkness, the wife has forgiven me and all lights in the house work properly and the blocks sit nicely in the track light mounting tray which means no need to make a big hole in the ceiling

once again many thanks, and as I have seen you have suggested before on this site, I will in future take a photo of the existing wiring before removing it or attempt to mark it etc as wired or just persuarde the other half to keep the lights that we have !!!
Meeki
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Joined: Wed Aug 20, 2008 4:45 pm

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