HELP !! Mad dimmer switch.

11 Jan 2003
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United Kingdom
Hi - just bought a dimmer switch from homebase. Inside it's got 3 connectors - L1, L2 and the wavy line with the arrow through it. The instructions that came with it are crap!!

Any offers on how to install it ???


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Ok mate - I will give that a try - thank you!!

If I don't get back to you after trying this - presume that I've fried!!!!


Hmmm - one problem.

Took the old existing switch off - there are indeed 2 wires. However, they are BOTH red!!!!

I read somewhere about the top and bottom of the switch telling you which wires are which ?

Any offers ??


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one is the switch wire and the other is your mains wire. Is there not an additional red sleeving over one of them? if so that is your mains. A testing pen would confirm which is your mains also, youll get one for under a fiver
If you have 2 reds then it will not matter much . The reason your cable has two reds is the electcian who installed it used the correct cable.

The regs changed, previously a cable with red and black (with red sleaving / tape over the black) could be used now you should use twin red, as the electrcian did
Surely though if they're put in the wrong way, the switch won't work ??? Or will blow up!!

I'm presuming one red is the common (permanent) live and the other just a switch wire ??

you are right about one being the live and the other the switch wire but no it will not blow up if it is the wrong way round :D

sorry i have just been testing the "new facilities" The first part of this post is orange, the bit i mention about facilites is green, and this bit is blue, not to mention the switch picture :evil:
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I agree with Breezer - your switch doesn't care which wire is live and which returns to the lamp. All it's going to do for you is connect the two together (via some dimming electronics in your case).

I purchased the same poorly instructed device too! Also from homebase..
I managed to connect it up (by following the instructions ) totally wrong and through pure chance am still alive! Spoke to a few friends and they advised the following:

The device MUST be earthed (IF purchased a metalic version.. Plastic dimmers don't require earthing)

1. Your neutral wire should connect to the arrow with the squibbled line..
normally the black cable..

2. The live connection should connect to L1

3. The dimmer can be earthed by using the yellow and green cable provided to connect to a screw found in the backbox installed in the hole
in the wall.

I managed to get mine working by following these steps.. hope it helps.. :)
i am sorry to say that as it reads you are totally wrong. I understand you are trying to help but you have made one near fatal mistake, you said NEUTRAL, there is no neutral required for any switches (unless it has a separate neon indicator)

As I previously mentioned it makes no difference which way round the switch goes one wire is live the other is switch (live) not NEUTRAL.

Incidentally the comment you made about the earth is also wrong. the wire you put on the earth contact on your switch is actually there to earth the metal back box, what you should do is to connect another wire from this to the earth on the metal switch.

The way your friend told you to do it relys on the screws making contact to earth the back box and this is known to be unreliable at the best of times

Also if you read the post where it mentions both wires are red, i mentioned that the electrician who did it has actually used the correct cable and that the black wire (in your case) should be marked as red. (because it is a switched live, not neutral

I had to point this out to avoid any one from mis understanding
What if you have two Reds and one Black (Both reds go in to the same hole on the old switch).
it does not matter, what you have when changing a switch that was installed by a qualified electrican, so long as you note what goes where before you remove the switch and put them back in the same way on the same type of switch (i.e one way)
Hello everybody.

My dimmer switch is failing.

So, I did something very silly. I removed the plate and had a look at the part number planning on replacing it, but did not switch the electricity off. It was fine, until I held both wires together. My fingers are still tingling.

So, now I know to switch the mains off. Very stupid thing to have done I know. I'm tired.

I have 1 black and 1 red wire, I believe that it does not matter which goes where (L1, L2)? But it is a brass plate. When I removed it, it was not earthed to anything. Shouldn't it be? And how do I go about earthing it?

Thanks in advance, from a very lucky and silly novice.
is there not a small terminal on the back of the switch itself (physically attached to the brass, nothing to do with the switch/) if so after you turn the mains off connect a 1mm wire between this and the metal back box that the switch fits into. there should also be another earth wire at this point which is the incoming earth.

The earth wire should be covered in green sleaving

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