Ceiling Light all wires same colour, help!

[renegade74]

I'm attempting to fit a new ceiling light in my bathroom but have come across a snag; there is a pair of wires connected & a single wire connected. The trouble is that they are all black so I have no way of knowing which is neutral and live. Can someone kindly advise me which is which. I've looked on the old fitting and it's not labeled at all. Thanks

 

[breezer]

use a meter and find out

 

[renegade74]

I don't have a meter, I was hoping that it would be obvious to an expert that the two wires connected to each other would be one or the other

 

[breezer]

doesnt work like that, they should not ll be the sme colour, but as they are anything could be anything, I suggest you buy a meter, would you expect to hit nails with a scewdriver?

 

[JohnD]

We can't see them, so probably not. Have you got a test meter, and is your house RCD protected? If "yes" and "no" there is a way. Otherwise, buy one for as little as a fiver. Or I suppose you could try a neon screwdriver, though many electricians frown on them.

You don't mention a green and yellow earth wire - is this a 1960's sort of house? And is your light fitting all-plastic? If there is no earth you mustn't use a metal one, and in a bathroom it must be enclosed.

 

[dingbat]

The trouble is that they are all black so I have no way of knowing which is neutral and live. Can someone kindly advise me which is which.

Generally the pair at the lights will be the neutral, with a corresponding pair of lives at the switch. This is the most common way of wiring lighting circuits in single-cored cable.

You don't mention an earth. If your new light requires an earth and you haven't one present then you should not be fitting that light. You really should not be working with mains electricity without any means of verifying what is present... and whether or not it is energised.

 

[renegade74]

Its a 1980's property, here is a picture

 

[breezer]

you never said they were twisted together.

the two that are twisted are neutral, the single is live

i dont like the way ist nbeen done, what is on the end of the reds that are poked into the ceiling?

 

[plugwash]

hmm looks like its standard loop in T&E after all thats just been bunched up into the ceiling. the wire on its own is almost certainly the live.

how are the other wires that are stuffed up against the ceiling joined together?

 

[dingbat]

That is horrible.

It looks like twin and earth. Belay my last post; the two reds together are the permanent lives. the two blacks together are the neutrals and the single black is the switched live.

Turn off the power, then bring both these twin and earth cable into the light fitting, so that the grey sleeving is inside. You need four terminals - one for the pair of reds (which do not connect to anything else in the light itself - you may need to provide an insulated terminal block). The pair of blacks go to the neutral terminal, the single black (which should be sleeved red) goes to the live terminal and the earths... well, I'll leave you to work that one out.

Do be careful that the insulation will not be subject to overheating (most bathroom light fittings are expressly designed to melt insulation!) and if uncertain, you should over-sleeve with heatproof sleeving.

 

[renegade74]

Thanks for the advice, here is a pic of the new fitting. It is chrome so does that have any effect of earthing it.

 

[dingbat]

It is chrome so does that have any effect of earthing it.

Yes, it must be earthed. It is provided with an earth terminal so make sure your circuit earths both go into it.

 

[JohnD]

Yes, as it's metal you must earth it, but the green-covered wires stuffed into the ceiling will be the earth. Your new lamp may have had some heat-resistant sleeving packed with it.

 

[Steve]

the wiring in that lamp - why did they not just connect both lamp wires to the choc block? Those un-nessecary joints look a bit fishy - like what they use in America, though these may be crimp connectors, i cant tell.

And to earth the front plate, the lamp is relying on continuity between the back and the front - 2 screws? The lamps i have wired have had a little metal lug attached to the front plate that feeds into the choc block.

 

[renegade74]

disaster, i've just fitted it, its three x 50w spotlights, tried it with one it came on fine so i attached it to the ceiling then tried it with all three & the main fuse box went bang! & now have no lighting at all in the house, what could i have done wrong!?!