Ceiling Light Replacement Woes

Hodge4ever

I've been in the process of replacing the ceiling light fittings in our house (from basic pendants to more modern ones), typically they have all gone to plan apart from the last one! :mad:

I think I may have got a bit cocky and not fully ensured I had noted the way the old light pendant was wired before I took it off

I have 3 red wires, 3 black wires and two earth wires. I was fairly sure that it was originally wired up as follows*;
3 red & 1 black -> brown
2 earth -> earthed
2 black -> blue

On fitting the new light I put them back as above, turned on the power and they light up seemingly O.K, however when I turned it off it blew the lighting fuse. I assumed I had made a mistake with the one black wire so tried;
3 red -> brown
2 earth -> earthed
3 black -> blue

followed by
3 red -> brown
2 earth -> earthed
2 black -> blue
1 black -> terminated

However both of these just left the light on permanently

I tried putting the old light fitting back up using the first scenario(*) however it blew the fuse again when turning off\on.

It's a single switch, single light (penultimate light in the ring) on a loop-in system (pics below). My first thought is that I have merely accidentally picked the wrong 'black' wire, if this is the case, is there an easy way to check? Also would that have been going into the same connector as the 3 red or have a dreamt that up?

I could check the black wires one at a time, but assumed that continually blowing the lighting fuse is really a good idea.

Any advice or links to explain it would be gratefully received.

booty40uk

3 reds on their own.
earths to earths
2 blacks to blue
1 black to brown

the black going to the brown will need to be sleeved with brown sleeving and you'll need to test to find oput which one it is. you'll also need to do something about those terminations into that connector block because they are terrible. you dont want any copper showing.

hth

andy

Hodge4ever

Hi Andy,

Thanks for your input, can I just confirm;
3 reds on their own ->
do you mean attach them together but to nothing else?

the black going to the brown will need to be sleeved with brown sleeving and you'll need to test to find oput which one it is. ->
How do I differnentiate between the three black wires?

I will also shorten the copper as suggested.

Regards,
Matt

YorkshireBoy

Hodge4ever wrote: »

Hi Andy,

Thanks for your input, can I just confirm;
3 reds on their own ->
do you mean attach them together but to nothing else?

Yes.

the black going to the brown will need to be sleeved with brown sleeving and you'll need to test to find oput which one it is. ->
How do I differnentiate between the three black wires?

Do you have some voltage testers or a continuity meter? If not, it's trial and error I'm afraid!

ormus

you need to find the switched live wire first. ( a black wire usually).
once you find that wire, its easy after that.

my quick method is to use 240v tester with someone operating the switch.
WARNING. not recommended to anyone else!
before the elf and safety brigade pile in.

Hodge4ever

Thanks for everyones input, did as suggested starting with connecting the wire I thought was separate to begin with to the brown, tested and it's all working great on the first attempt :j

Just out of curiosity, what are the red wires actually for?

ormus

the light circuit is a ring circuit just like the power sockets.
hence one red in, one red out, to the next rose.
the third red is to the switch. which then returns, via the switched live wire (black with red marker). hence its name.

ormus

KillerWatt

ormus wrote: »

the light circuit is a ring circuit just like the power sockets.

Lighting doesn't make the return back to the CU, if anything it is a radial circuit.

molerat

KillerWatt wrote: »

Lighting doesn't always make the return back to the CU, if anything it is usually a radial circuit but not always.

edited for clarity

I would like to know what happened to the third cpc :eek: