Fitting a double dimmer switch

Jimbob950 · Dec 5, 2021

I have 2 red and 2 black cables. Only 1 red is live. How do I wire this switch?.

telectrix · Dec 5, 2021

a pic. would help. usually the permanent L goes into C or the terminal marked ~. linked to 2nd switch same terminal. then each black (switched L) into L1 of each switch.

Jimbob950 · Dec 5, 2021

telectrix said:
a pic. would help. usually the permanent L goes into C or the terminal marked ~. linked to 2nd switch same terminal. then each black (switched L) into L1 of each switch.

Thanks for your reply. I was thinking of linking up the live with the ~ and connecting with a bridging wire to the corresponding ~ on the next switch.
Then as you say connecting the blacks wire to the L1 connections. Does this mean that I do not use the other red cable which is not live.
The old switch which was fitted, probably 45 years ago was a triple rocker switch but only two working and there were two bridging wire between
some of the terminals.

SJD · Dec 5, 2021

Jimbob950 said:
Thanks for your reply. I was thinking of linking up the live with the ~ and connecting with a bridging wire to the corresponding ~ on the next switch.
Then as you say connecting the blacks wire to the L1 connections. Does this mean that I do not use the other red cable which is not live.
The old switch which was fitted, probably 45 years ago was a triple rocker switch but only two working and there were two bridging wire between
some of the terminals.

Post a photo of how the old switch was wired. You did take one, before removing it, I trust?

Jimbob950 · Dec 5, 2021

telectrix said:
a pic. would help. usually the permanent L goes into C or the terminal marked ~. linked to 2nd switch same terminal. then each black (switched L) into L1 of each switch.

Further to my reply just sent. Does the spare red connect to the ~terminal on the second switch?

Jimbob950 · Dec 5, 2021

SJD said:
Post a photo of how the old switch was wired. You did take one, before removing it, I trust?

Sorry I took one but it is not too good

westward10 · Dec 5, 2021

Jimbob950 said:
Sorry I took one but it is not too good

Put it up it may be better than nothing.

Avo Mk8 · Dec 5, 2021

Jimbob950 said:
I was thinking of linking up the live with the ~ and connecting with a bridging wire to the corresponding ~ on the next switch.

I thought the ~ wavy line symbol was the output of the dimmer (ie feed to the lamp) so may not be good to connect permanent L to it.
Or do dimmers work either way round these days?
Let me know if I've got the wrong end of the ~.

Jimbob950 · Dec 6, 2021

westward10 said:
Put it up it may be better than nothing.

[ElectriciansForums.net] Fitting a double dimmer switch

Avo Mk8 · Dec 6, 2021

Sorry, what with my eyesight and your pictures, I can't make sense of that

Edit: well, looky here, I finally did!!

How many switches are on that plate - sorry, just seen you've said 3!

can you confirm - in your middle photo:
For the switch on the left, the COM terminal is away from us
For the switch in the midfle, the COM is nearest us
For the switch on the right, the COM is away from us
Are they all 2-way switches, each with three terminals?
Update - I think it looks like this:
Can you confirm??

westward10 · Dec 6, 2021

Hard to see but it is a three gang switch with a line in which links across them all but not across all Commons, one is in L2 due to the switch configuration from what I can make out but that is not relevant. Two outgoing lines in the L2s of the outer switches. @Jimbob950 can you confirm the middle Common has no wire connected.

westward10 · Dec 6, 2021

I think the middle common does have a wire in it now I look again as per @Avo Mk8, a pic I didn't see initially but I would say is correct.

Avo Mk8 · Dec 6, 2021

My suggestion is - whichever switch is the one you no longer need, or doesn't do anything, remove that feed to the lamp from the old switch and insulate the end of the wire with a Wago or similar, That's not to be used any more.
Then for your two dimmer switches, connect the live feed presently linking the switches to L1 on each dimmer.
Then connect the dimmer tilda ~ terminals to the remaining two lamp feeds.

Sort of like this (not my art!) - blue and yel representing the two lamp feeds, stating the obvious!

Jimbob950 · Dec 6, 2021

westward10 said:
I think the middle common does have a wire in it now I look again as per @Avo Mk8, a pic I didn't see initially but I would say is correct.

Avo Mk8 said:
My suggestion is - whichever switch is the one you no longer need, or doesn't do anything, remove that feed to the lamp from the old switch and insulate the end of the wire with a Wago or similar, That's not to be used any more.
Then for your two dimmer switches, connect the live feed presently linking the switches to L1 on each dimmer.
Then connect the dimmer tilda ~ terminals to the remaining two lamp feeds.

Sort of like this (not my art!) - blue and yel representing the two lamp feeds, stating the obvious!
View attachment 92666

Jimbob950 · Dec 6, 2021

Avo Mk8 said:
My suggestion is - whichever switch is the one you no longer need, or doesn't do anything, remove that feed to the lamp from the old switch and insulate the end of the wire with a Wago or similar, That's not to be used any more.
Then for your two dimmer switches, connect the live feed presently linking the switches to L1 on each dimmer.
Then connect the dimmer tilda ~ terminals to the remaining two lamp feeds.

Sort of like this (not my art!) - blue and yel representing the two lamp feeds, stating the obvious!
View attachment 92666

Fitting a double dimmer switch

Jimbob950

telectrix

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Jimbob950

SJD

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Jimbob950

Jimbob950

westward10

Avo Mk8

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Jimbob950

Avo Mk8

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westward10

westward10

Avo Mk8

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Jimbob950

Jimbob950

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