New ceiling rose with 2 switches


Postby dcv89 » Sat Jan 19, 2008 3:44 pm

Hi everybody, hope someone can help

I am trying to fit a new ceiling rose for a light that has 2 switches. Each switch controls this light and another light.

I removed the old light and ceiling rose, stupidly not taking notice of how they were connected. Now I cannot get it wired up so that it works.

Basically, there are 4 wires coming from the ceiling. I assume that there is one power in, one out, and one cable to/from each of the switches.

Even if I can identify which are the switch cables, how do I then connect them all up? My ceiling rose has the following: 3 connections for 'Loop', 2 for neutral and 1 for live (as well as the connections for the cable from the lamp ).

I really hope this makes sense! Thanks in advance for your help
dcv89
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Postby ericmark » Sat Jan 19, 2008 6:07 pm

I would look on projects page a picture is better than words. Also many other replies in the forum where others have made the same mistake. But I would not expect the two light switches to be wired back to the lamp. Normally twin and earth from light to first switch and three and earth between both switches. So four wires are likely to be one feed in, two feeds out and the switch wire. I did in true Blue Peter style do a standard answer there was a link which you may find in earlier pages to web site but this is not allowed so here is standard answer.
Regular question:- How does one wire a ceiling rose? The switch wires should be both red or at least have a red sleeve but in practice this is rarely the case. This is how to work out which black/Blue wire is which when all three cables are the same colours. These are:- The feed, The Switch, The next Lamp. Easy way is meter or buzzer across the cables with power all off and flick light switch until switch wire is found but often the DIY man has no meter or buzzer so next method.
Do not use energy saving bulbs as we need to be able to see bulbs working on half power use normal bulbs only. Do not use this method if you have dimmers or discharge lamps in any of the house lights.
1. With power off connect all cables except for neutrals and switch cable i.e. the black or blue are left disconnected. Put one into spare block connecter and other two in the two outer connectors of the ceiling rose i.e. one to each wire feeding lamp. Now turn on power and try if it works jump to 4. If not turn off power.
2. Swap either of two blacks (or blues) connected with one in spare block connecter and then turn on power again. If it works then jump to 4. If not turn off power.
3. Swap the wire in spare block connector with other black (or blue) in ceiling rose. It should now work one switched on again. If not there is another fault not at rose and it is beyond this simple check.
4. Turn off power again and mark cable in spare block connector with black or blue type or some other way to find it again. Then put it in spare hole with other Black (or blue) then turn on power.
5. Test all lights if all work OK then all is done on the other hand you may find odd things happening like with light you have been working on being switched on other lights don’t work and with it off the other lights work as glow only and light you were working on will also start to glow. If this is the case switch off power and swap the two unmarked black (or blue) wires. Now all should work.
So what are we doing? Well we can’t connect any of the three blacks (or blue) together as one is live when switched on so to start with we find out which wire connects to the next rose in circuit by time 1, 2, and 3 have been completed we know this is wire is spare block connector. At this point, we don’t know which of the other two blacks (or blue) is neutral and which is the switch wire. But if we connect the next lamp in series to switch instead of neutral it will do no harm but the next lamp can only get a return through the lamp in the light we have been working on so either the one we were working on will come on dim or the next in line will come on dim which is all to do with what size bulbs are fitted. But we now know exactly which two wires are the wrong way around. So finally we have in the eight holes in rose (earths normally under clamp screw) Feed to lamp, Feed from switch, break, Three live wires at all times all red or brown (one feed, one out to switch and one to next lamp), break, Neutral (in or out), Neutral (out or in), Neutral to lamp.
ericmark

Postby dcv89 » Sun Jan 20, 2008 10:01 am

Thanks for your help Ericmark.

Maybe I should add that when I first took the old rose off, I noticed that there were 2 black wires feeding into the live wire from the light, and 1 black wire feeding into the neutral. Also, one of the red wires and one of the black wires were joined at a connection box. I can't remember how the other wires were configured.

Does this make sense and does this change any of your advice?
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Postby dcv89 » Sun Jan 20, 2008 12:21 pm

Hi, just a quick update

I have used an electricians screwdriver to check which cables are the switched live, and there are 2 of them (ie 2 black cables that show up live when I switch the power on).

So I tried to put both of them in to the live connector in the ceiling rose and the rest of the cables in the right place (reds together, other blacks together) and it still doesn't work.

Any more ideas? Thanks again
dcv89
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Postby ericmark » Sun Jan 20, 2008 12:36 pm

Reading your reply it seems you have some non standard wiring. At which point it becomes impossible to advise even on site one can make errors when working on non standard systems sorry you need to call someone in.
ericmark

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