replacing single dimmer with a double dimmer

[robinson14]

Hello I hope someone out there can help me. I have a single dimmer which controls two sets of lights and i want to change this to a double dimmer so the lights at either end of the room can be controlled seperatley. I have two brown wires that go into L1 and two blue wires that are connected by a block and two earth wires in the old switch. The new double dimmer has two L1 two L2 and two com. It is probably so easy to do but i just cant get it working.

Thankyou

 

[breezer]

so if you have 2 wires in L1 what have you got in C?

the way i read it you only have 2 wires in L1 an no other connections in the switch (yes i noted the 2 blue wires in the choc bloc)

I am not going to assume anything

 

[robinson14]

Hello

I have nothing in the com the switch only has two wires in L1 and two blue wires in the bloc and thats it!!

 

[Steve]

And did this switch ever work? The way you describe it, it would never have worked. Ever.

 

[breezer]

I agree with crafty1289, that is why i never assume anything

 

[securespark]

I am going to dare to assume something!

If the two conductors in the same terminal were live loop & switched live, the light would be on all the time, but it is not, from what the OP has said.

So, there must be a missing live feed somewhere? Probably attached to the same cable as one of the neutrals (another assumption!)

 

[robinson14]

i'ld like to apologize i have one brown wire in L1 and one brown wire in com!! Sorry

 

[dingbat]

Now that's settled your questions is easily answered.

You can't do what you want without running in another cable... with all the associated mess that involves.

 

[danlightbulb]

Just worth checking that the blue cables in the choc block are neutral. Cos there is a chance that they are lives from each light looped together to create the parellel circuit.

If thats the case then splitting them and putting a small piece of wire between the coms of each dimmer would work. Its an outside chance but worth a look.

Use a multimeter on the terminals of the choc block to see if they are live.

I say this because its unusual for neutrals to be taken down into a light switch, isn't it? A spark can confirm this (i'm not a spark).

 

[Spark123]

I doubt it, if they are phase wires they should really be sleeved brown. It is becoming a more common practice to run neutrals to light switches; what this sounds more like is a phase, neutral & earth cable has been run to the switch, at the switch the neutrals are connected in block, the earths connected together (and the box?) and the phases are connected across the switch. The wire with switch phase, earth and neutral runs to the light. The other light has likely been connected in parallel to the first.
If the blues are neutral and is connected as you say there will be a direct short across at least one dimmer switch and it will go bang!! So it is a must that before doing anything the function of the conductors as you say needs to be established with a multimeter.

edit; I have put a picture in the wiki under single way lighting re loop in switch; click here