need help wiring a double light switch

breadbin

i have a kitchen light switch that used to be a dimmer but lately hasnt been working at all and just trips all the time when on so basically i have no light in the kitchen apart from a plug in lamp. the switch controls 12 recessed lights, the first switch the near 6 and the other the farther 6 lights.

i bought a replacement switch, turned off all the power in the house and labelled the wires going into the old switch. i'm not replacing it with a dimmer but an ordinary double switch. i replaced all the wires but its not working, still tripping.

i have 3 brown wires coming into the backbox and an earth, and these are going into L1 on the right side, L1 on the left switch and the last brown is going into the common (on the left side), then there is a small wire connecting both common terminals. does this sound ok? the fact that there is a brown wire going into only one common sort of threw me. the lights come on for a split second before it trips.

i'm guessing i'll have to get an electrician out but maybe someone can spot something straight away before i do and save me a few bob. thanks

meercat

If it is tripping then the fault is not with the switch.
Check the transformer or the wiring at the affected downlights.


The switch wiring connections seem correct.

Irish Steve

You should be able to pin it down a little by only switching one of the 2 on at a time, in theory, with the way you've described the set up, half of the lights should be OK, and the other half has a fault somewhere.

If they are recessed lights, they may be 12 Volt, or mains, if they are 12V, then it's possible that a transformer on one of the lights has failed, if they are mains voltage, it could be that one of the bulbs has failed in a way that's causing a short, so the circuit breaker is tripping when you switch on, so when you know which set of lights works, take all the other bulbs out (use a tissue to handle them if they are 12 V to avoid skin oils contaminating the lamp) and then try turning that section on, if the trip still goes out, it's not a bulb issue, but a wiring or transformer that's causing it.

A quick way to tell if the lamps are 12 V or mains will be to look at the way the bulbs connect, if they are screw in , then they are mains, if they are small pins and push in, then they will be 12 V, and there will be one or more transformers, probably mounted above the ceiling, which may mean removing the lamp holder to get access to the transformer, or transformers. There's no way to know if there is one or multiple transformers, the most likely is one per lamp, but that is not a certainty.

If it's transformers, it may be possible to disconnect one at a time (power off of course) without leaving bare ends around, depending on the way they are connected, (most are a screw connector, or possibly a junction box with terminals or a screw connector block inside it) and if that's the case, then that will allow you to remove one transformer, try the power on again, and if it's a faulty transformer, at some stage, the trip will not blow out, and you can put all the rest of the bulbs etc back, and get a new transformer and fit it. If the supply cable to the transformer is still in a screw connector or junction box, then it will be safe to use the lights until you can get a new transformer.

If it is transformer based and you want to put a dimmer in to the system again in future, make sure that the replacement transformer is suitable for dimmer use, not all transformers can be used with dimmers.

If you end up with no transformers connected and it still blows, then life is becoming seriously complicated, as that means there is some form of wiring fault, but that's unlikely, a bulb or transformer is the most likely suspect.

Hope that helps