How to wire a replacement (three or) four-gang switch (eg a dimmer)
I now feel like I could cure a rainy day! Fixed it, and report it here as it was just so damned simple in the end that others similarly perplexed might benefit from my new-found genius!
I was replacing a four-gang one-way-operating switch, and the dimmer was a potentially two-way one. The lettering on the old switch was confusing (A1, A2 and B, etc), as was the V-shaped arrangement.
But all you have to do for a one-way set-up is this... (after turning off the mains!
)
Each switch in the 'gang' is a separate switch. So it needs an 'in' and an 'out' for the leccy to flow through -- a live and a neutral wire going to it. So in a two-way switch you've got three terminals each: L1, L2 and C.
L is Live, and there's two of them for two-way purposes: that's the L1 and L2. The terminal labelled C is for something called Common, just to confuse you. Ignore whateverthehell 'common' is, and think of it as Neutral.
Your conventionally-coloured cable from the wall has three wires -- a red and a black (or would it be a blue and a brown in more modern homes?), and an earth, probably connected to the back of the metal box.
So you've got one live wire, and you need to connect it to all four switches. Still with me?
So what you do is link all the 'live' terminals of the switches together -- all the things labelled L1 -- with bits of wire. (I assume that you'd link all the L2's together too if it's a two way, but again someone will correct me if not.)
For some reason best known to the manufacturers, this is not done already. You have to provide your own 'strapping' wires.
Get some cable that has either red or brown wire. Someone can correct me if it
must be only one or other of those, but the principle is that you need to indicate 'live'. About half a meter will do, but you'll need more than you might think just by looking at the 'straps' required.
Extract the wire from the cable and, measuring against the switch, cut more than enough to reach from one L1 to the next. Strip the ends and link 'em up, L1 to L1 across the switches.
Then connect the Red (or brown?) live wire from the wall to the first switch, into its first L1 -- into the same terminal as the strap wire.
So each switch now has a live source going in, linked across from the first one by the straps. It now just needs an 'out', the neutral.
The first, normally-coloured neutral (black, or blue?) then goes into the C terminal of the first switch. That first switch is now connected.
Then take that other cable in the wall, the one with the confusing, never-seen-those-colours-on-cables-before colours. Effectively (and I don't care if the terminology is right here), they are all neutrals, one for each light / thing that's separately switched. So put one wire each from there into the C (ie, as above, the 'neutral') terminal of each switch.
As far as I can see, the only difference each one makes is which light etc is then operated by that switch.
Screw it back on the wall and turn the power on again.
As I say, I couldn't quite believe that my thinking-it-through, after being stumped by diagrams that didn't match what I was seeing, had worked.
So I hope I'm not telling anyone anything wrong, but I hope I've described what I did clearly, and it worked for me...
If in any doubt, though, call an electrician. Me, I'm spending the fifty quid I've saved on new light fittings
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