DIY Doctor

New 2 gang 1 way switch

Postby bigdigger » Tue Oct 11, 2011 9:42 pm

Hello I'm new to this forum and would appreciate any help or advice on the following :-
I have recently attempted to change a double light switch that operates 2 sets of lights in the living room independently - until i started to replace it !.
1 switch operates the 2 wall lights and the other switch operates the ceiling light.
On removing the old switch I was horrified to find that the new light switch had totally different parts to the one i was replacing. In the switch casing there are 4 red wires that come out of 4 different white cables that went into the old plug and a common earth wire, i have managed to put the right wires (4 red and 1 earth) in the right holes i think? after many tries and both lights now work as they should except that one light comes on when the switch is in the off position - to get to this stage has taken hours - however when screwing switch to wall using metal ? screws the lights do not work again as they should .
Does the metal screw form part of a circuit when contacting switch and bit you screw it to.The switch is earthed
Any help / advice much appreciated
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Simply Build It

Postby BLAKEY1963 » Thu Oct 13, 2011 8:18 am

Project pages show switching arrangements commononly encountered.
Any deviances from this might need you to get someone locally to help you.

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Postby ericmark » Thu Oct 13, 2011 10:47 pm

As BLAKEY1963 says your best looking in the projects as we can't post pictures and it is so much easier with pictures.

The earth should not effect the working of the lights so the 3.5mm fixing screws should not effect how the switch works. Switch labels are not all the same. Some use the marking Com and others call same terminal L1 so it is hard to detail exactly how to connect.

There are tree basic switches used with lights. The on/off with just two connections although often the same moulding is use as with the others so often there is a hole that looks as if it's a termite but is empty. If these work wrong way around only cure is to physical mount switch other way up.

The next is the two way switch these have three terminals and can still be used as on/off switches. Changing the wire from highest number to second highest number or vice versa i.e. L1 with L2 if there is a com or L2 with L3 if no com will swap which way is on and which is off.

And final there is the intermediate which can be used for all options. Because different makes are marked differently I always check with a meter.

In theory on/off switches will have a single cable feeding them normally a twin and earth. The two way will with one switch of pair have a triple and earth cable and other one will have a twin and earth plus a triple and earth cable both switches of the pair with have the triple and earth cable with same colours to same terminals. The com with a two way set up will only have one wire both other terminals will have two wires with one switch of pair. Not going to go into intermediate switches.

Having said that in years gone by some electricians would borrow lives so they did not need to use triple and earth cable once this happens to work it out become a problem.
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