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Extra black cable on lighting pendant

Postby Lyn123 » Tue May 27, 2008 10:52 pm

I am trying to replace the rose pendant on my landing and I stupidly removed the old fitting without making a note of the position of the cables.

The house is three stories and the hall light on the ground floor and the light on the top floor landing are controlled together by either the switch on the landing or one in the hall.

I have three pieces of flec comming in (1.5mm red, blue and earth). I know one of these must be the feed in , feed out and switch but am not sure which is which. First question how can I find out.

I also have a singe black wire comming in. It looks like 1.5mm neutral cable but from memory was twined together with a red cable. Second question what on earth is this.

Currently none of the cableas are connected and none of the top floor lights or downstairs hall light work.

I have checked the fuse box and there is only one 5amp fuse which when switched off turns all the lights off.

Help we are currently in the dark upstairs.

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Simply Build It

Postby ericmark » Wed May 28, 2008 8:33 pm

We would normally "Ring out" the cables. This means with power off we connect a buzzer (Normally built into meter) on each set of cables until we locate to switch wires.
Trial and error can't be used as wrong switch wire identified can cause a direct short.
If it were not for your extra black wire there is a long winded way to work it out I have explained it in posts before but it seems people reading the posts have not found them easy to follow so I think you really need a spark.
The switch wires would normally be marked with red tape or sleeve.
There is a project section that may help.
I will post the instructions below since it's only a cut and paste job but I don't think in your case it will be much help.

All best Eric

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.

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