Two cables from ceiling light socket

[ChilliBob]

Hey guys,


Hoping you can help, I took a light down from our kitchen as we want to replace it. I was a little hasty and didn’t take a photo of the wiring, a rookie mistake! Looking at it now I’m slightly confused, coming from the celing there are two cables, each has blue, brown and yellow/green.


The yellow/green (earth) is twisted together to form one cable. From memory the two brown were shoved into the same socket on the light, however, I can’t remember the blue, I *think* each blue cable had its own socket (the light fitting had more than three terminal sockets if that’s the right phrase).


The new light I have has three sockets, so obviously the earth goes to the earth, however, do I just put two live and neutral in each of the other respective sockets?


If not I guess I may need to use one of these? http://www.diy.com/departments/bq-white-15a-6-way-cable-connector-strip/178058_BQ.prd but I’m not 100% sure how?


I have my Dad coming round to assist and he seems to know what I’m talking about (he’s not seen it yet) but I thought the opinion of others on here would certainly be valuable too.


Thanks

 

[bernardgreen]

Almost certianly this is what you have in the wiring.

One cable is the feed bringing power from the fuse box ( consumer unit ) this will be Permanent Live ( brown ) and Neutral (blue )

The other cable will be to the switch,

The brown will take Live to the switch so needs to be connected to the brown that is Permanent Live
The blue will be the Switched Live back from the switch. It should have a brown sleeve on it.

Neutral from the consumer unit goes to the blue or N terminal in the new light fitting

Switched Live goes to the Brown or L terminal in the new light fitting

( Yes the two blues go to the light fitting )

The two browns join together in a fourth terminal block and do NOT connect to anything other than themselves. Permanent Live from consumer unit connected to Permament Live going to the switch.

Providing there are only 2 cables and no other lights controlled by the switch the above should work and it does not really matter if you cannot identify which cable is from the consumer unit as it will work if the cables are wrongly identified. but only if there are only two cables

 

[ChilliBob]

Thanks for the quick and detailed explanation. My new light has three connection sockets, whilst the one I took down had more sockets, I'm thinking that this means it won't work unless I get something extra (or else). The new light simply has Live, Neutral and Earth.

So I can connect the combined earth, leaving 4 cables and 2 sockets... it sounds like I'm supposed to put a blue from each into the remaining live and neutral (which seems to go against the grain), which means I have nowhere to put my two browns. Hmm!

 

[bernardgreen]

You will need to buy ( or scrounge ) a terminal block to join the two browns together.

From Maplins for example

http://www.maplin.co.uk/p/5a-terminal-blocks-3-pack-l97ar

which is a pack of 3 strips each of 12 terminal, 36 when you only need one. It can be a good idea to replace the existing 3 terminal strip in the new fitting with a 4 terminal strip but if you do ensure the earth connection from terminal block to lamp fitting is maintained.

or a local garage or car parts shop may have them in smaller quantities.

 

[ChilliBob]

Ah right, like the thing from B&Q that I linked to, my Dad may have some knocking around, however, I think my girlfriend may be in B&Q this evening

If I don't replace the existing block in the light (which without looking (it's packaged up and I'm at work!) is probably glued in place how would I go about this? I'm trying to think if/how I connect the two blocks together. I'm sure my Dad will know what the deal is when he sees it but I thought I'd try to educate myself a bit first!

I think he said it would be a connection from a light somewhere else so all the cables would need to be connected so that other lights worked too. Which also makes sense I guess.

 

[ChilliBob]

I've been pondering this, if I understand you correctly I think I need to do this:

Place the twisted earth into the earth socket.
Place a blue cable into the live socket.
Place the other blue cable into the neutral socket

Place both brown cables together into a terminator block, just cut a 1 length section from a block, screw both in from the same end.

Does that make sense?!

 

[bernardgreen]

Yes it does make sense. You can put the two browns both into the same end or one into each end of the terminal Whichever make it easier to fit the terminal block into the avialable space.

And it is terminal not socket. Plugs go into sockets, wires go into terminals.

 

[ChilliBob]

I did think my terminology might be a bit off there, thanks for the correction. Whilst I don't need to know this I guess, are the two browns connected together like this to 'complete the circuit' so to speak? I suppose the fact that they were all connected to the same block before is kind of irrelevant if the two browns were going into the same terminal, and there was nothing on the other side of the terminal.

 

[PBC_1966]

Whilst I don't need to know this I guess, are the two browns connected together like this to 'complete the circuit' so to speak?

Yes. Power is coming into the fitting on one cable - Brown live, blue neutral. If you just connected those wires directly to the light, the light would work, but you'd have no way to turn it on and off.

The second cable runs to the switch, and needs to be connected so that the switch interrupts the live feed to the light. Hence the incoming brown live from the supply is connected to the brown wire in the cable which goes to the switch. The blue coming back from the switch is then not a neutral but a switched live, and connects to the live terminal on the light fixture. It's common to put a piece of brown sleeving or tape around that blue switch wire to identify it as live.

The same arrangement exists with cables more than about 10 years old, with red in place of brown and black in place of blue.

 

[securespark]

Deleted for being mean.

 

[Echo the husky]

Deleted for being mean.

It wasn't that mean! You merely asked a question!

 

[ChilliBob]

Ah I'm curious what the mean question was! Oh well, never mind! I've attached a picture of the cables, as someone said above there is indeed the sheath on on of the neutral cables, so that would seem to tall which is good.

Also it looks like the holes from a light before the one I removed may fit the same centers, which would be nice

 

[securespark]

Deleted for being mean.

It wasn't that mean! You merely asked a question!

Thank you, but on reflection, I felt it was unnecessary.

 

[securespark]

That wiring is well cooked!! One giveaway is the cracked skim on the plasterboard showing it has got hot over the years.

The others are discoloured pvc insulation and sleeving and cracked insulation.

You will have to see if you can pull any slack gently out of the void.

If not, you will need to access the space above and joint it out with a MF junction box.

 

[ChilliBob]

Thanks for that, I did notice they were a bit tatty, they're pretty long so I think I can snip some junk of them and get clean wires. The bathroom is above, with freshly layed tiles, on top of ditcromatting and plywood! Access from above is a no go!