Only wiring on dimmer

Hi, I am just replacing an old dimmer (covered in burn marks). There are 3 red wires. I think there were 2 red in one terminal and 1 red in another. Does it matter which way around they go back if being replaced with a standard switch? I couldn't understand why there were three cables and not two?

Yes it does matter. They go back in the same order they came out with the same ones grouped together.

I take it you assumed wiring is just a case of stick random wires in the holes and it doesn't matter, so you did not bother to mark them in any way so you could put them back as they were?

If you have 3 then it's a safe bet you've a looped live at the switch, get them wrong and you could end up switching more than one light. oops!

It's probably going to have to be trial and error then.  Since there are only 3 wires you will just have to try all 3 possibilities as to which is the single wire.

If you get it wrong, nothing will blow up, but your room light switch might turn lights in other rooms on or off, or may not turn off at all.

just don't do what a local DIYer did recently .............. 2 way dimmer, so he connected the live, switched live AND CPC to the dimmer terminals!

Ok, thank you. It works. I think I guessed correctly. The new switch has L1 and L2. So I used these for two of the red wires which I think were combined in one terminal in the old switch? Also, I noticed on the new switch, there is no earth connection? Only in back box.

cjonesguitar said:

Ok, thank you. It works. I think I guessed correctly. The new switch has L1 and L2. So I used these for two of the red wires which I think were combined in one terminal in the old switch? Also, I noticed on the new switch, there is no earth connection? Only in back box.

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To be honest that doesn't sound right. I guess there is also a "C" as well as L1 & L2.   So you now have three separate connections to your new dimmer(?).

I think you may find some other light in the house doesn't work OR  works only when the circuit you have worked on is OFF.

Don't worry about the earth. Plastic faced dimmers usually don't have one.

Yes that is correct there is C also. I assumed L1 and L2 are connected regardless of switched live or not. Replaced with dimmer with just standard switch... the other option is that I put both into same terminal.

Same comment applies, Just read "Switch" for ""dimmer"" in my comment.

Have you now made two connections into three? Does everything else still work?

Ok, I understand. Tomorrow I will check. 3 connections everything seemed to work. I understand how the two way switch works now.

Later   . .  I tried to remove my own appendix but seem to have a few extra bits left over.....  can someone tell me where they go ? 

Bruspark said:

Later   . .  I tried to remove my own appendix but seem to have a few extra bits left over.....  can someone tell me where they go ? 

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Did you not take some pics and label all the bits first?

randomly connecting nerves to tendons and arteries to mesenteric tissue will eventually get everything working BUT not necessarily how it should be .  You don't really want to be suddenly and randomly defecating in Asda every time you scratch your nuts , do you?

It all worked so put it back together.