Dimmer help for novice please

[Egg90]

Hi. I'm trying to replace a standard double light switch with a double dimmer and am confused about the wiring I found behind the original switch.

The two Commons are bridged from one brown wire. The two L1's have their own brown wire & the L2's are not connected. The spare wires are 3 x blue and a 3 core yellow/green.

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• Egg90
• 19 Feb 2015
• 1

Here is the dimmer. It has a metal front plate, separate ~1 and ~2's, a shared L, and a front plate earth.

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• Egg90
• 19 Feb 2015
• 1

Here is the wiring diagram that came with the dimmer.

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• Egg90
• 19 Feb 2015
• 1

Also I'm a bit worried that the dimmer says Min load 60W. One switch will control a single 42W halogen light and the other will control two 42W halogen lights.

I wont waste your time by explaining what I think I could do, if someone could say how to proceed that would be great.

 

[stem]

The live supply that is presently linked into the two commons, put in the central 'L' terminal (discard the link) and then the other two browns go in the L1 terminals of each switch. If the dimmer works in the opposite way to what you would like, ie starts dim and gets brighter, or starts bright and gets dimmer, swapping the wires from L1 to L2 will change that over.

The diagram shows the option for two way switching, which you don't have.

Some types of dimmer need a certain load in order to work, you are a bit below on one, so it may not work.

The earth wires need connecting to the terminal block on the metal faceplate.

Leave the blues as they are.

 

[Egg90]

Ok thanks very much.

I was thrown by the fact that there were 3 brown wires connected, when from the diagram I was expecting 1 brown & two blue, along with the fact there were blue wires there but not connected, and the difference of labelling between Common, L and L1/2, ~1/2.

Your explanation makes sense, thanks again.

 

[EFLImpudence]

along with the fact there were blue wires there but not connected,

Yes they are - connected together.

The minimum loading is a problem, though (for one of them).

 

[Egg90]

Sweet! Everything seems to work how it should. Is there a danger or issue of one going under the minimum load even if it seems to work fine? Maybe there is just a large tolerance?

 

[stem]

If they are underloaded, sometimes the light may flash when it is dimmed. I'm not aware of any safety issues as a result of underloading a dimmer. Someone will no doubt say if there is. In any event, you are loading it at more than 2 thirds of the minimum rating, and I would imagine that there is a margin on the figure given.

 

[333rocky333]

If the dimmer works in the opposite way to what you would like, ie starts dim and gets brighter, or starts bright and gets dimmer, swapping the wires from L1 to L2 will change that over.

.

I wasnt aware of that

 

[securespark]

I have been fitting dimmer switches for well over 25 years and never heard of this!!

 

[stem]

Must admit, I've not tried it with any dimmer switches recently, but I'm sure I remember swapping the wires over on one of the old rotary only type to do that. Perhaps it changed when they went to push 'on' push 'off' switches.

 

[ban-all-sheds]

Here is the wiring diagram that came with the dimmer.

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• Egg90
• 19 Feb 2015
• 1

1) It assumes a particular way of wiring switches which is not always done.

2) It does not show the earth connected directly to the switch, which it should.

3) It does not show the use of sleeving to indicate blue or black as a line conductor, which it should.

I was thrown by the fact that there were 3 brown wires connected, when from the diagram I was expecting 1 brown & two blue, along with the fact there were blue wires there but not connected, and the difference of labelling between Common, L and L1/2, ~1/2.

You really, really, ought to learn more about how things work before deciding to fiddle with them.

//www.diynot.com/wiki/Electrics:Lighting

 

[securespark]

Must admit, I've not tried it with any dimmer switches recently, but I'm sure I remember swapping the wires over on one of the old rotary only type to do that. Perhaps it changed when they went to push 'on' push 'off' switches.

The rotary type are 1 way only.