Lighting Circuit

AD1 · Posted: Sun Oct 02, 2005 12:35 pm Post Subject: Lighting Circuit

hi - hope someone can help.
I have a hall light that is 2 way and need to fit a new pendant - but being a donkey, I did not write down the wiring positions.
I have Earth, Neutral and Live on my pendant. From the ceiling, I have a 3 core wire and a 4 core wire. The 3 core has a black, Earth and Red. The 4 core has blue, earth, red and yellow. I assume the yellow is power. Can anyone pls tell me what joins with what. The switch is 2 way. thanks

plugwash · Posted: Sun Oct 02, 2005 12:41 pm Post Subject:

thats NOT a normal combination!

whats the wiring like at the switch?

ban-all-sheds · Posted: Mon Oct 03, 2005 11:11 am Post Subject: Re: Lighting Circuit

AD1 wrote:

I assume the yellow is power

Why?

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kendor · Posted: Mon Oct 03, 2005 11:27 am Post Subject:

plugwash wrote:

thats NOT a normal combination!

whats the wiring like at the switch?

it is if it's conversion method
3 core and earth between switches.

AD1 it's likely that the red in what you call the 3 core( which is actually twin and earth) is live although some bright spark may have made the black live but it doesn't matter as long as you mark both cores red with tape.
Connections are as follows: at the switch with two cables connect the red from what you call the 4core cable ( which is actually 3 core and earth) to the common terminal on your two way switch, in L1 put the red from the twin and earth cable with the yellow from the 3 core and earth cable.
Connect the remaining black(marked with red tape) and blue wires to L2
at the other two way switch ( just the three cores there)the connections should be as follows:
red to common, yellow to L1 and blue to L2. obviously earths go their respective terminals in the back of the switch boxes.

ban-all-sheds · Posted: Mon Oct 03, 2005 11:46 am Post Subject:

Err - kendor - I suggest you read the Q again - he has T+E and 3C+E at the ceiling rose, not at switches...

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kendor · Posted: Mon Oct 03, 2005 11:49 am Post Subject:

ban-all-sheds wrote:

Err - kendor - I suggest you read the Q again - he has T+E and 3C+E at the ceiling rose, not at switches...

Ban agreed it could be read that way but i have read it again and i beleive he has not been clear in his description and that at the switches he is quoting the cables read again and you might see what i mean.

ban-all-sheds · Posted: Mon Oct 03, 2005 11:58 am Post Subject:

kendor wrote:

Ban agreed it could be read that way but i have read it again and i beleive he has not been clear in his description and that at the switches he is quoting the cables read again

OK.

AD1 wrote:

I have a hall light that is 2 way and need to fit a new pendant

So he's talking about a new light fitting on the ceiling, not a new light switch.

AD1 wrote:

I have Earth, Neutral and Live on my pendant.

So he's got a new light fitting for the ceiling, not a new light switch.

AD1 wrote:

From the ceiling, I have a 3 core wire and a 4 core wire.

kendor wrote:

and you might see what i mean.

Sorry, no....

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kendor · Posted: Mon Oct 03, 2005 12:04 pm Post Subject:

Ok ban "from the ceiling" could mean he's at the switch and two cables disappear up to the ceiling do you see what i mean now? he's not been clear enough in his description and it could be taken bothe ways, so although i'm not disagreeing with your interpretation , i believe he meant the 3C+E and twin and earth are in fact at the switch which he has removed this would seem the logical place to find this arrangement.

ban-all-sheds · Posted: Mon Oct 03, 2005 12:08 pm Post Subject:

Ah well - no point arguing - we'll wait for the OP to respond....

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kendor · Posted: Mon Oct 03, 2005 12:09 pm Post Subject:

yep agreed

AD1 · Posted: Mon Oct 03, 2005 12:25 pm Post Subject:

sorry for the confusion, the wires are dangling from the ceiling. My reference to the switches is that the light is operated by 2 switches (hence 2 way). I assume yellow is power because in new builds I thought that was the lighting power cable - I may be wrong.

I cannot see tape on any of the wires.

thanks

++++++++++++++++++++++++++++

sorry - forgot to add that I am doing nothing at the switches - they are fine.

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Gary0 · Posted: Mon Oct 03, 2005 12:42 pm Post Subject:

I believe the problem was, from which point are the cables dangling from the ceiling. But I think we can assume from the point where your light fitting is/was.

In which case there is something wrong with the way the circuit was wired. Have a check with the diagrams in the sticky thread.

The blue, red, and yellow cable is for connecting between 2 switches, it shouldn't normally go near the light. Although I have seen (and not paid too much attention too) circuits whereby both switch cables end up at the light fitting (rose or junction box) and one core is just connected through. I'll see if I can find the diagram.

Ultimately I think you need to open up the switches and note what cable/core is connected where, to each. If you can work out where they end up, it become less of a task to work out how they need to be wired at the light.

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Darn, checked last week's history on this PC, no dice. May have seen it on PC at home, but in any case I think I've worked out what the diagram must have shown.

The following for interest only, as a possibility, do check out what it is you really have.

If 4 cables came into the rose or junction box at the ceiling then 2 can be accounted for as mains in, and mains out (if this is the end of the run there may not be a mains out as unlike rings one doesn't tend to feed the end back to the c/u).

Remembering that the colours are interchangeable in the following description (although obviously you have to make any changes consistent throughout

consider the following ...

3rd cable goes to one switch, 4th cable to the other.
At both switches yellow (for example) is connected to the common, blue and red to the other two connections.
Back at the rose or jb, yellow from each cable is just connected together so effectively goes from one switch common to the other.

Red (for example) on both switch cables, gets connected to the live at the rose. Blue (for example) on both cables, gets connected together and treated as the 'switched live', and taken to the lamp.

This, of course, assumes that there are cables still up in the ceiling that you are not aware of yet.

Now that may not be what you have, and I'll check the diagram (just in case that description goes bang

) I've just sketched out again, but when you check what you have at the switches, you may find that, that just might be what you started with.

Personally I'd try to rewire it more conventionally if I were you, in any case.

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Well blow me down if it wasn't right here on this site after all !

The cable saving pic here

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ban-all-sheds · Posted: Mon Oct 03, 2005 1:41 pm Post Subject:

plugwash wrote:

thats NOT a normal combination

... for a hall light.

Gary0 wrote:

The blue, red, and yellow cable is for connecting between 2 switches, it shouldn't normally go near the light

...in a hall.

It is reasonably common at the ceiling roses in bathrooms and toilets where a L/SL/N supply is taken to a fan.

PS - Kendor - you owe me a bacon sandwich and 3 illegal acts.

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plugwash · Posted: Mon Oct 03, 2005 4:53 pm Post Subject:

ban-all-sheds wrote:

It is reasonably common at the ceiling roses in bathrooms and toilets where a L/SL/N supply is taken to a fan.

indeed but that would only bee seen if it was a loop in fed rose with a fan spurred off it, he only has one twin and earth cable at his light so it can't be a loop in rose with a fan spurred off it.

kendor · Posted: Mon Oct 03, 2005 9:32 pm Post Subject:

apologies for wrong interpretation of post.
That is indeed a strange setup and i'm trying to think how it could work as a two way circuit unless there is also a cable going between the switches.
reason i say this is because there are only 5 cores involved bar an earth having been used illegally conversion method wouldn't work in this case as the connections are at the rose not at the switch. Alternatively if wired as live, strappers and switchline then there would still need to be more cores.
as suggested unscrewing of switches in order to ascertain what is going on would be necessary now. Also is there a Joint box above from where these two cables come from? this may explain the lack of cores with interconnecting being done before the two cables appear at the rose.