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Replacing old BS646 Dimmer Switch with Modern 1G1W Switch

Postby h2whoa » Tue Dec 15, 2015 11:09 am

Hi all,

Just moved into a house with an old dimmer switch in it, that requires a BS646 3A fuse to work. The fuse has gone, so was thinking I'd just put in a modern 1G1W switch. The front of the existing dimmer looks like this.


The wiring at the back (this house has the old UK wiring colours) has 2 reds in L1 and a yellow in Variable Load.


I'm thinking that all I need to do is put the two reds in the Common of a new switch and the yellow into the L1. Does this seem right to you experts?

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Simply Build It

Postby ericmark » Wed Dec 16, 2015 2:40 am

There is a colour code old red in line and new brown in line, but yellow is not given a function in a single phase system so it is up to the user to work out what it does. Likely you are OK but that is just a guess.

Today dimming switches have some odd wiring, I have seen instructions which state do not connect to mains this is low voltage! Well mains is low voltage clearly they mean extra low voltage but still call it in error low voltage.

So it is a case of carefully reading instructions and working out what they really mean rather than what they say.
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