Having unscrewed the main light fitting from the ceiling of the bathroom, I find it has two live wires and two neutrals. WTF? It's on a normal ceiling mounted pull-switch.
Only thing I can think of is that once upon a time there was a timer attached doing burglar-scaring duties.
Now, I got two mounting holes 2 inches apart - where can I get a light fitting???
Are you sure you have identified the cables correctly? If the light fitting is on a loop in system, with no loop out, you would expect (as well as the cable to the light itself) a live+neutral feed and a switch cable. The switch cable is usually just normal black+red cable, although technically it should be either red+red, or have red sleeving on the black wire to indicate it is a switched live. However, this sleeving is frequently omitted, or is done using red insulation tape that has lost adhesion and fallen off.
Christian.
Do you mean two lives and two neutrals or two reds and two blacks?
If the latter this is normal for the last light on the circuit - a feed and the switch drop.
Two blacks going in to one terminal, a black and a red going to the other. All wired into some sort of terminal block, which has got three reds into it, and the three reds all coming out of one terminal on a terminal block... as far as I can see in the recess.
Doesn't really matter, as long as this is normal, but I'm afraid I don't understand why a lamp needs more than two wires going in to it...
Thanks also to Christian.
If anyone's got a good URL to explain this loop and switch drop stuff, I'll read it before asking any more questions.
This is most likely:
The two blacks will be neutrals, one the supply and one for the light fitting. The red and black will be the switched live, one for the light fitting, one from the switch. There should only be two reds into the other terminal which will be the unswitched supply live, one for the supply and one for the switch. Having 3 reds into this terminal is a bit odd, unless there is an additional neutral somewhere you have missed.
Christian.
Well it's *all* completely hatstand as far as I can see. The lightbulb's got two terminals. I would expect two wires into it. Bit o' ASCII:
----------- switch --------------- live | x lamp |
----------- switch --------------- neutral
is what I would expect.
So what you're saying is you take your mains to the light fitting first and then off to the switch?
On Tue, 23 May 2006 15:50:16 GMT someone who may be Mary Pegg wrote this:-
Assuming that you have left out the wires going down to the lamp itself, these are probably the incoming neutral and the neutral to the next light in the circuit. Another wire, black or more likely blue, will go from this terminal to the bulb holder as well.
This is probably the switched live. The black cable should be sleeved to indicate that it is live, but this is often not done. Another wire, red or more likely brown, will go from this terminal to the bulb holder as well.
Probably the incoming live, the live going to the switch and the live to the next light in the circuit.
Because the switch needs to be connected somewhere and the light is often a good place to do it. Also because there is unlikely to be only one light on a lighting circuit and so the following lights need to be fed from somewhere.
Any electrical retailer. Its called a 'ceiling rose'
Your wiring MAY be just a switched live 'on its way somewhere' or it may be that the icoming mains is one pair, and the other pair simply goes to the switch. In which case simply wiring red to red and black to black will result in a healthy bang when you turn the light on..
Yes.
One way of wiring lighting is for the mains from the consumer unit going to the ceiling rose in one room, from there to the next room and so on.
But the bit of wire down to the lamp isn't connected directly to this live/neutral pair.
Instead only the neutral side is connected directly, the live goes off to the light switch then comes back after the switch and finally down to the lamp.
Uses a lot less cable than zooming from the consumer unit to each switch and then to each ceiling rose!
Yes. It is here with pictures.
This might help:
In message , Andy Wade writes
You need a junction box somewhere to get the feed to the switch and the neutral for the other side of the fitting, so it makes some sense to incorporate that in the ceiling rose. But it's not so convenient when you want to replace a standard pendant fitting and rose with something else.
Hi Mary,
Don't know how you are getting on with your reading, and how confident you now feel about tackling this stuff, but bear in mind a few points.
Whilst it is only permitted (under the new(ish) Part P building regs to use the new wiring colours, that doesn't mean you can't use the old ones - we won't tell honest!
Part P does say that things in a bathroom must be done by a qualified sparky who can self certify the work else you have to get building regs approval.
Also only certain types of fittins are allowed for bathrooms (mostly enclosed I think).
That said, apart from the light fitting I put in our last bathroom, i've yet to see an enclosed fitting in the real world, and even the Daily Wail isn't filled with the pictures of the hundreds of dead bodies resulting from this lack of compliance with current regs.
HTH
Regards
Zikki
****************************************************************************************************** That's Mr Zikki to you Fuzzy!DOD 6809
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It all depends on the zoning. In many bathrooms, the zones will allow standard light fittings.
Christian.
This looks to be the key point in your misunderstanding. Your diagram shows what is known as a two-pole switch - ie it contains 2 linked switches one to switch the line 'pole' & the other the neutral 'pole'..
Double pole switches are used in uk domestic wiring (such as in switches for extractor fans and water heaters) but lighting circuits only rarely use this arrangement.
Normally only the live supply is switched. Live and neutral go to a junction box, which may be a separate fitting or which may be incorporated in the ceiling batten (the loop-in system). A separate live-and-return cable goes to the single pole wall switch from the junction box (or the loop-in combined light batten).
The other factor you may be overlooking is that lighting circuits are normally fed power on a radial circuit. Ie the live-neutral supply runs from one lamp to the next in line, rather than power to each light being fed separately from a hub or star supply point.
HTH
Nope, I meant two wires going in to one terminal on the bulbholder itself.
Anyway, I think the folk here have given me enough Clue and handy URLs for me to figure out what's going on.
Nope, I would appear to have a recessed ceiling rose (IYSWIM) - and I want a replacement light fitting that will go flush to the ceiling and screw into the two mounting points on the recessed rose.
It really /is/ bizarre. It would appear that (at the least) one terminal on the bulb holder is being used as the equivalent of the bottom-right terminal block in the top diagram on this page:
2" holes are standard for electricals so any *decent* British light fitting should have the requisite holes already supplied.
Owain
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