Lots of additional wiring!!
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nad1611
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Lots of additional wiring!!

by nad1611 » Wed Mar 25, 2009 3:33 pm

Hi
Prior to getting an electrician in I thought I'd have a look and see if I could refit a bathroom light. I have the old black and red wiring and know black-blue and red-brown. I presumed it would be a straightforward case of just reinserting these, however having taken down the old light fitting there are lots of wires. There are 4 lots of red and 4 black wires coming through inside grey insulation in pairs, in other words black and red times 4. My new light fitting only has one brown and one blue wire.
This is obviously something I will need help with but out of interest why are there so many and where will they all go into the new fitting?
Thanks

kbrownie
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by kbrownie » Wed Mar 25, 2009 10:46 pm

Hi nad1611,
What you have is a loop in loop out circuit, The black and red pairs are as follows:
1)you will have a in coming live and neutral, feeding it a supply
2)an out-going live and neutral, supply to the next fitting on the circuit
3)A pair of switch wires
4)and some one has took another feed from this to else where by the sounds of it. suppling another peice of equipment.
Firstly, You need to identify your switch wires does any of the blacks have a red flag on it?
KB

nad1611
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by nad1611 » Thu Mar 26, 2009 1:51 pm

thanks kbrownie. This is a very straight forward explanation thanks. Unfortunately none of the wires have a red falg/sleeve on it. Any suggestions?

kbrownie
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by kbrownie » Thu Mar 26, 2009 5:42 pm

A pair the red and black go to your switch, we need to find out which pair.
Do you have a multi meter? and if so do you understand who to work it?
If you do it is a lot easier, if not trial and error. Unless the room is above the loft space in which you can trace the cables.
KB

nad1611
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a small breakthrough

by nad1611 » Thu Mar 26, 2009 8:58 pm

I have had a much closer look at things. Three of the black wires are actually wound round each other where the copper wire is exposed so I can only presume these all went into the same place. But shouldn't they be continuing the circuit and have other wires going from them surely they cant just be in isolation altogether?
Also I remember removing some of the red wires from a ?terminator(is that what it's called) after doing this two of the bedroom lights now do not work so they obviously supplied that. These red wires were made up of two twisted together going in one side of the terminator? and a single red wire entering the other side. This would then only leave one remaining black and a remaining red. Would this description make things any clearer for you to advice?

kbrownie
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by kbrownie » Fri Mar 27, 2009 7:54 am

OH YES!
Right all your reds should be terminated together in a connection block if this termination is not available via ceiling rose or connection to light light.

The Three Blacks (twisted together) go to the connection at the blue flex side of the the light. This will give continuity of the neutrals

The spare black is your switch wire (not a neutral) returning a live feed via the switch make this up with brown or red sleave for future ref. Connect that to the Brown Flex side of light.

The Lights should now work okay. Do you have any earth cables green/yellow sleaved or sometimes left bare? If not don't use metal light fitting unless it is double insulated.
KB

nad1611
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by nad1611 » Fri Mar 27, 2009 10:18 am

[quote="kbrownie"]A pair the red and black go to your switch, we need to find out which pair.
Do you have a multi meter? and if so do you understand who to work it?
If you do it is a lot easier, if not trial and error. Unless the room is above the loft space in which you can trace the cables.
KB[/quote]

I don't have a multimeter but I know how it works and that it can test the live wire which in my case actually looks like a neutral wire. This is what I think is going on;
The two red wires that are wound together I have now returned to the block with the a seperate single red wire now at the other side, the bedroom lights that weren't working are now okay, so this is obviously supply in and supply out to the other rooms and therefore are not connected to the new lamp at all..

The three black wires which are all twisted together therefore should go to the neutral blue in the new light fitting.That then leaves us with one black wire which should be the switch live and should go to the brown live in the new light fitting but I am still left with one red, now if I have this right this red belongs with the other reds and does not need to enter the new light fitting at all?, but should it go with the reds which are going in a pair into the block or with the single one on the other side?

If this isn't right I'll get someone in but I think I have it okay, just need verification!

kbrownie
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by kbrownie » Fri Mar 27, 2009 11:52 am

All reds together as previous post, when you say you have two reds in a connection block and one connected to the other side of connection block, I assume you mean directly opposite, as this will connect all together as they are linked across block. Put the spare red in the block with the single red for ease of termination. The multi meter would have helped us find continuity of the switch wires, so we would be sure that was them.
KB

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