Light fitting help

[Ian]

Hi...

Hopefully someone can offer me some advice.

I bought some 240v 50hz 50w haligen spot lights to fit in my kitchen. My intention was to put up a plasterboard ceiling with three spot lights chained together sourced off the existing socket.

The ceiling is currently solid concrete and has one standard light fitting in the middle. I disconnected the light fitting to find in total nine wires. They are:

Three live wires twisted together, put in a connector block, taped up and pushed into the back box. i.e. not connected to the light. Three Earth wires the same as the live above. Two Neutral wires twisted together and connected to the light fitting One Live wire connected to the light fitting.

Why so many cables ?, should I just connect the new lights to the same wires as the existing one and forget about the others?

By the way the new lights do not need to be earthed.

Any help would be much appreciated. Ian.

[usenet]

Basically, yes. This same question must come up just about once a week on this newsgroup!

The normal way of wiring lighting is to 'chain' a feed (i.e. live and neutral) unswitched to all the light fittings. Then take a pair from the fitting to the switch for that fitting.

At your fitting you thus have:- Three red/live wires, two are the 'chain' (one from previous fitting, one to next) and one is the feed to the switch. Two black/neutral wires together are the 'chain'. One black wire by itself (should be marked red to indicate it is live) is the switched live from the switch. The earth/CPC wires are the chain and the switch earths all connected together.

Leave everything connected as it is and connect your new lights to the same wires as the old light was connected.

OK, just leave the earth wires connected together as they are at present.

[Ian]

Chris,

Thanks for your help. I've taken another look at it and with your help it all makes perfect sense now!

The live feed from the switch is actually red rather than black with a red mark for some reason. I've looked at the switch and there are two reds and one green. guess they ran out of black wire!

Got one more question about amp ratings but I'll post that seperately..... thanks again.

Cheers, Ian.

[Bob Mannix]

Sometimes light switches were wired with two single core cables (grey outer red inner sheath). This avoided the "black with a red mark possible confusion (so you couldn't find a live black wire somewhere) but just causes more confusion and was more fiddly to wire up and didn't transfer the earth to the switch. It's possible it dates from the 1960's

[usenet]

That's actually 'very correct', both wires to the switch should be read really as they're both live. It's just that in the real world not many electricians have T&E cable with two red wires so the compromise solution is to use normal black and red with the black wire marked to indicate that it's live.

[Lurch]

On Fri, 13 Aug 2004 08:00:33 +0100, "Bob Mannix" strung together this:

Quite true but in this case it sounds more like a new installation with twin and earth with two reds in it like this;

[Andrew King]

I had exactly the same problem with an old light fitting I was replacing, only my black switch live cable didn't have red bands, I also needed to unwire all the cables from each other to fit it all in the new light, so I lost which cable did which from the old fitting.

When it came to figuring which black cable was switch live I couldn't remember, so i resorted to turning the electricity back on and testing them with an electric screwdriver..!!

It was the first light fitting that I've ever done, and I was shaking for about a day afterwards... the moral of the story is, always check that your switch live cable has a red band on it before proceeding..!

Andrew.