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double dimmer switch

Postby armytouch » Thu Feb 28, 2008 2:04 pm

hi,i have decided to convert my double light switch to an double dimmer switch in the kitchen one switch turns on under unit lighting and other main ceiling lighting,however on opening the double switch have found 3xred cables and one yellow cable then a choc with black n brown cable connected together.
I have connected 1xred to com and yellow to L1 on one side of dimmer swith,then the other 2 reds to the other side of dimmer switch then linked the com to L1.left the black n brown connected in choc block.
what i get is that one dimmer switch when pressed turns both sets of lighting on,but 1 each dimmer controls each set of lights to dim. I wanted each dimmer switch to control each individual lighting, one for ceiling on and off and dimming,and other for under unit lighting off n on and dimmer control. Each dimmer control inside switch as a com+L1+L2 connection.
Please help.
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Postby ericmark » Thu Feb 28, 2008 9:25 pm

Your cable colours do not seem to make sense. A yellow cable would have a red and a blue with it? A Brown cable should have a blue with it? Using a choc block either points to cross over switch not a simple two way or originally wired like school boy two way switching not standard system used in houses.
On standard wiring of two way switches L1 and L2 connect to live and lamp plus other switch plus com on both switches connect together so with a double two way switch you need at least 5 wires connected to the switches you only list 4 so either you have missed some in your account or it’s not a two way switching system.
Two way = Two switches working the same lamp form two different locations.
Two gang = Two switches moulded into the same switch plate.
Intermediate = A third or more switch used in a two way system.
Sometimes where extra low voltage transformers are used instead of ceiling roses neutrals are brought into the switch box but this is not common so.
• How many cables and how many wires in each cable and what are their colours.
• How was it originally wired.
• How many terminals were used in old switch.
• Was there a link wire used with old switch.
• Do you know colours in other switches that work same lights.
I know something is wrong with your account but not what unless someone else can see what you are doing.

Postby armytouch » Fri Feb 29, 2008 6:18 pm

hi thanks for reply,originally the double switch had an intermediate control from other side of room which was removed.So the double switch controlled one set of lights on one switch and the other lights were controlled by 2 switches in room.when i looked inside double switch there were 1x yellow disconnected plus 1x blue which i take are from the intermediate cables that had been removed.however there are also black and a gray cable connected together in choc could these need placing into the double dimmer switch to control the lighting controls.
If you could list the number and colours of cables needed to control a double dimmer switch then break down in which blocks inside the dimmer each colour should go,for some reason 1 of the dimmer switches is controlling both lets of lights but the dimmers when turned control brightness,i think maybe one of the red cables is from the intemediate part of the old circuit,maybe i can disreguard the intermediate cables which i take it would have been 3 core + earth.thanks
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Postby ericmark » Sat Mar 01, 2008 1:14 am

There is no real standard. All Line cables should be Brown or old wiring regulations Red but this makes it very hard to trace which wire is which so normally twin and earth and triple and earth are used. These should have brown or red sleeves fitted to each cable which could become line but these are often missing. So since they are should be brown or red there is no laid down colour code. Also there is two ways that two way lights can be wired. School boy method and domestic electricians method the latter has the advantage of requiring no choc blocks. Even the switches are not all the sames some using L1, L2, L3 and others using L1, L2 and Common. With the latter switch one is sure of connections but the former really needs a meter to be sure on how it is connected. I have diagrams of how it works on my web site but I am not allowed to give links on this forum it is a web site with same name after the www as I use to log on to this site there was talk about repeating it on this site but it seems a non electrical guy who tested it could not follow it.
Normally two way switches use the triple and earth between the two switches and the same colour goes on to the same switch connection on both switches. On one switch you will double up on the wires going into the L1 and L2 if there is a common on the switch. L1 and L2 may be swapped it will only change if switch up or down for on and if L1 is Line then L2 will be Switch return to lamp. (electrician type wiring not school boy) For a switch without Two way L2 will not be used. Although if you mount switch upside down swapping wire from L1 to L2 does same as rotating switch 180 deg and makes the switch work the right way around. Because your wiring has been messed around I can't really help much more sometimes we are lucky and we can work out what has happened but sorry I can't in your case, maybe one of the other guys on line will make a better job of working it out but I think it is going to require a visit by an electrician. Sorry ericmark

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