Dimmer Swicth - Haven't a Clue. Please Help

[stealth1701]

Hi
I'm hoping one of you experts out there can help me fit a dimmer switch.
My set-up is as follows.

I have a room with two lights at either end of the room (the wires for both lights come into the same switch box. What I want to do is fit a double dimmer switch so that I can choose whether to have one or both lights on and can dim each one individually.

I went to Homebase and bought a Decor Dimmer Switch - two rotary knobs with a push on/off action.
Inside the switch are two identical grey units side-by-side with one turned the opposit way to the other (ie upside down). Each of the units has an L1, L2 and squiggly line with an arrow going through it (ie there are a total of 6 terminals I can push wires into)

OK, on my wall there are two grey plasic sleeves each having a number of wires coming out. One sleeve has two red coated wires coming out and an earth (which is connected to the metal plate in the wall). The other sleeve just has a single red coated wire coming out of it.

The question is, where do I stick each of these wires given the configuration described above (L1, L2 & ->)

Hope I have described this in enough detail and really hope someone can help.
Thanks in advance
Mat

 

[pdcelec]

The answer is in the "Sticky- For Reference" on the index page

 

[Adam_151]

Take the red from the T&E to one of the commons (wiggly line with arrow), and use a another put of red cable as a jumper to the other common, then put the black (which you should put a bit of red sleeving on)from the T&E in one of the L1 connections, and the red from the DI single in the other L1.

If the switch is metal, then take the earths to the front, then take another earth from that to the backbox.

If the controls work the opposite lights than what they should, then swap round the wires in the L1 conenctions.

 

[ban-all-sheds]

Take the red from the T&E to one of the commons (wiggly line with arrow), and use a another put of red cable as a jumper to the other common, then put the black (which you should put a bit of red sleeving on)from the T&E in one of the L1 connections, and the red from the DI single in the other L1.

All very well, but:

on my wall there are two grey plasic sleeves each having a number of wires coming out. One sleeve has two red coated wires coming out

Mat - you will need to identify which wire is the permanent live - did you make a note of which ones went where on the old switch, or do you own a multimeter?

 

[Adam_151]

Oh ****, I can't read

 

[kendor]

one thing to point out is the terminal marked with the arrow through a sine wave(squiggly line) is the dimmer output the arrow denotes variable.

 

[ban-all-sheds]

Mat - if you didn't make a note, and don't have a meter, you should do this:

1) Look at the info in For Reference so that you understand how light switches are wired

2) Refit the old switch and try the two combinations of connecting the twin red and see which one works and which one doesn't, and then mark which wire is which.

You can't do any harm with getting the wires in a normal switch mixed up, but if you do the same with a dimmer and accidentally get the two in series this might not be a good thing...

 

[stealth1701]

Hmmm. Thanks for all the replies, but I'm still none the wiser really. OK so the squiggly line is a variable output right? and L1 & L2 refer to live inputs I assume? So The fact that I have 3 wires and 2 lights, how does that work? You obviously can't have an input and output for each light correct (since there is only 3 wires)?
I'm really confused - would appreciate any detailed advise so I don't have to go and pay an arm and a leg for an electrician to come out! I feel i'm missing some vital piece of information here that would help me do this
Any other suggestions?
Cheers
Mat

 

[pdcelec]

The answer is still in the "Sticky- For Reference" on the index page

 

[Lectrician]

The TWO core cable contains a LIVE FEED.

Put his into the L1's (yes both of them!), use a short length of cable to link from one L1 to the other. This way, both L1's now have the constant feed.

The other red from the 2 core cable will be the switched live for one light, and the single red will be the switched live for the other. Put these in the two squiggle terminals seperately. These are the 'outputs'.

Forget about the L2, this would be for two-way switching.

It's a pitty you have a twin red cable. These are fairly rare, it is more common to see a twin cable with red and black, and the black having a little red sleeve on to identify it as a live. If you did have red and black, the red would be the constant live, and the black the sw live. BUT, as you have a red/red cable, you need to determine which is constant live, and which is switch!

 

[stealth1701]

I looked at the "sticky for reference" pages but cant see the answer to my specific question. can you put a hyperlink to the page you are refering to. thanks

 

[Lectrician]

posted at same time!

 

[ban-all-sheds]

I looked at the "sticky for reference" pages but cant see the answer to my specific question. can you put a hyperlink to the page you are refering to. thanks

//www.diynot.com/forums/viewtopic.php?p=36621#36621


The part of that post headed "CEILING ROSE WIRING - STEP BY STEP" - shows how ceiling roses are wired, and how with a single switch you have one cable which brings permanent live to the switch and takes switched live from it to the light. Your cable that does this is (probably) the twin red one, like the Lounge Switch in the diagram.

So obviously if you have a 2-gang switch to control 2 lights, one way is to link the permanent live feed at the switch from one COM to the other one, and use a single core cable to take the 2nd switched live to the 2nd light.