Double Dimmer Wiring Problem

petercape · 7 Apr 2005

Hi everybody

I've searched around but can't find somebody with my specific problem. I'm replacing a double switch (2 gang?) with a double dimmer. The wiring in the switch:

Black - 1 way

Red - 2 way

Blue - 1 way

Red - common

Yellow - common

The dimmer switch is marked up differently. Am I right in assuming "one way" is equal to "L1"?

The thing that is particularly troubling me is: the wavy line with an arrow through it. Is that where the red and yellow (common) wires go? (I read it indicates no DC. But does that apply in this case?)

Or as I suspect, have I got the wrong dimmer? If so, could somebody tell me exactly what I need, please?

Many thanks

P.

pna · 7 Apr 2005

There are 2 things to be clear on:
- one gang/ two gang / three gang switches - how many switches there are - each switch operates a separate light
- one way/ two way switching - how many switches operate an individual light. Two way switching is usual for hall/ stair lighting, where two switches both operate the same light.

Is the existing setup two gang and two way?

If you take a look at some of the diagrams in the 'for reference post' these show two way wiring, which should start to make things clearer.

The wavy line is meant to be common.

Big_Spark · 7 Apr 2005

Black - 1 way

Red - 2 way

Blue - 1 way

Red - common

Yellow - common

This implies you have a TWO GANG, TWO WAY SWITCH THAT HAS BEEN WIRED AS A ONE WAY SWITCH AND A TWO WAY SWITCH

If the dimmer only has four terminals then it is a TWO GANG, ONE WAY switch and is no good for what you want to do.

You will need a to buy a dimmer that is TWO GANG AND TWO WAY

Ensure that you keep the cores in their respective terminal or you will mix up two circuits and niether will switch right.

petercape · 7 Apr 2005

many thanks to the both of you for the info and help.

i've managed to get both lights working, but now the living room switch (two gang, two way), which hasn't a dimmer and also controls the landing light, turns on in reverse. i've read elsewhere that it's the red L2 (dimmer) wire i need to move. is that correct? and if so, where does it go?

thanks again.

breezer · 7 Apr 2005

try L1

petercape · 7 Apr 2005

breezer said:
try L1

thanks for the reply, breezer, but L1 has got the blue in one and the black in the other. i checked the note i made of the previous wiring and i've made no mistakes.

could it be the L2 red into the other vacant L2?

thanks again.

mapj1 · 7 Apr 2005

to reverse the sense of a 2 way switch, swap L1 and L2 at one of the two switches (but not both, otherwise, like the man who found he could make his trousers more comfortable to walk in by swapping one leg from one side to the other because he first put both legs in the same side, moving a second leg accross will makes the problem re-appear...)
Whatever you do, don't muddle in any wiring that relates to the switch or dimmer for the bank of lights that are working as intended.

petercape · 7 Apr 2005

mapj1 said:
swap L1 and L2 at one of the two switches

thanks for the reply, mike. forgive my stupidity, but by that do you mean swap the black L1 with the Red L2?

Black - L1

Red - L2

Blue - L1

Red - common

Yellow - common

thanks again.

mapj1 · 7 Apr 2005

Look at the switch, and see if you can deduce which L1 and L2 form a pair with which common - the colours mean very little without knowing what is at the other end - there is no particular guarantee that the origianal wiring followed a particualr convention.
Rememer there are really two identical, but totally independant switches buried in that block of plastic (don't be confused if as they are often fitted '69' to save space though, so the commons of the 2 switches may be on opposing sides)

I'd expect Red+black to be one switch, the one with no second switch

and red blue yellow to be the other, the one with 2 way control.
However, its not guaranteed that he thought the way I would !

On any one switch, to reverse its sense, swap the wires between L1 and L2, and leave common as it was. (obviously to turn over the 1 way switch, as L2 is no connect, L1 becomes no connect instead.)
Come back if still bemused

petercape · 8 Apr 2005

Woo hoo! Thanks, Mike. And, yes, he did think like you (maybe it was you? Spooky).

Thanks again.

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Double Dimmer Wiring Problem

pna

Big_Spark

breezer

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