Dimmer switch

[spwbarton]

Hi,
I am trying to install a new double dimmer switch to replace a normal double light switch, but the old wiring / new switch is confusing me.
My old switch has L1, L2 and Com, but the new switch only has L1 and Com. The connections to the old switch are:
L1: Red and Blue
L2: Red and Yellow
Com: Red
Plus there is a single red wire running between the two L2s.
Can anyone tell me how I might configure the new switch?
The picture shows the old switch, from left to right, L2, L1, L2, L1 (2x Coms are hidden from view).
Thank you

 

[PrenticeBoyofDerry]

Have you a picture of the terminals on the new dimmer. Sounds like you have purchased a dimmer with one way functions only and not two way.

How are the second ways, switched on other switch plates?

 

[spwbarton]

Hi - thanks for your help - image of the new switch attached.

 

[PrenticeBoyofDerry]

Yes the switch you have purchased is for one way function only. You need a two way switch to replace a two way switch.

 

[spwbarton]

Thank you very much!

 

[ban-all-sheds]

Also, please note that if you do this, then switching the light on using the (other) 2-way switch, not the dimmer, it will come on at whatever brightness the dimmer was set to, so you might have to walk over to the dimmer to adjust it. Not much of a problem if it's in the same room - could be a bit of a pain if it's on a different floor.

 

[spwbarton]

Hi,
I had one further question - I have the two way switch now and all looks good. However, on the old switch there is a red wire running between the two L2s. (In the first picture posted it is the left-most wire on each side.) Does anyone know what this is for and whether it is necessary? I am struggling to get it to fit with all the other wires.
Thank you

 

[PrenticeBoyofDerry]

It is to connect the permanent live across both switch gangs, without it one of the gangs will not get power, thus not work.

 

[ban-all-sheds]

It is to connect the permanent live across both switch gangs, without it one of the gangs will not get power, thus not work.

So what's wrong with, or being done by the red from the twin red cable that's in the L2?

 

[spwbarton]

I'm not sure - both lights / dimmers now working fine (but without the red cable that connected permanent live across the L2s, which I could not get to fit). Thanks for your help.

 

[ban-all-sheds]

The connections to the old switch are:
L1: Red and Blue
L2: Red and Yellow
Com: Red

It does look like it from the photo, but just to confirm - both gangs of the switch are like that?


What is the wiring like at the lights which these switches control?

 

[spwbarton]

Both gangs are the same, yes.

Wiring at the lights is standard but a bit tatty (old house) and old colours.

 

[PrenticeBoyofDerry]

So what's wrong with, or being done by the red from the twin red cable that's in the L2?

I don't know, was not part of the installation. When a link is put across two gangs, it would suggest that that link is perm/com live.

 

[ban-all-sheds]

Indeed.

But in that case one of the reds in the cables to/from the switch would have to not be a permanent live.

However it seems that they both are:

both lights / dimmers now working fine (but without the red cable that connected permanent live across the L2s

What kind of numpty puts a link in which is utterly pointless?

 

[PrenticeBoyofDerry]

What kind of numpty puts a link in which is utterly pointless?

One that is ignorant and likes to confuse the issue.