DIY Doctor

Replacing Light Switch With Dimmer Switch and Confused by the Wiring!

Postby jc1303 » Sat Jul 25, 2015 12:22 pm

Ive just moved house and am working my way through the list of DIY projects.
One of the jobs I was looking at doing is replacing the light switch in the living room with a dimmer switch. Ive done a bit of reading up on the internet and most things I read said that there should be a red wire and a black wire attached to the existing switch. Turned the power off, took my switch apart and there are 2 red wires in the common terminal, 2 red wires in the other terminal and 4 black wires not connected to anything!
What is going on?
Can anyone advise how to connect a dimmer switch to this or should I just get an electrician?!?!
Many Thanks
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Simply Build It

Postby ericmark » Sun Jul 26, 2015 7:37 am

It would seem the switch back box is being used as a junction box rather than the ceiling rose, this is common when extra low voltage lighting is used as there is not loop connection in the transformer.

So there should be no problem using just the red wires if the light is of a type able to be dimmed.

Quartz lamps should not be dimmed it causes the quartz to go black as it will not be hot enough. LED and CFL plus any lamp using an electronic transformer has to be matched to the switch. Not only leading and lagging but also make to make.

Personally all dimmers in my house have been removed were all the rage in the 1980's but now the dimmer restricts what lamps can be used.
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