disabling a 2 way switch

clupton · Posted: Tue Aug 14, 2007 4:11 pm Post Subject: disabling a 2 way switch

Hi
I have a 2 way light in my front room controlled by a switch by one door and a double switch at the other which also has a switch to the kitchen.

I want to know if its possible to disable the switch on the double controlling the front room light and thus allow me to fit a dimmer to the remaining switch for the front room.

If so how do i go about it?

Many thanks for any help

davy_owen_88 · Posted: Tue Aug 14, 2007 4:16 pm Post Subject:

Depending on which switch your live feed and switched live go to, it could be an easy job (just remove the 3-core+e cable from both switches) or a complete pain in the ass.

How many cables are at each switch? A photo would be helpful. Remember to turn off the 'leccy before you remove the switch front.

clupton · Posted: Tue Aug 14, 2007 4:35 pm Post Subject:

single switch in front room has 1 red to common, earth and red to 1 way and blck to 2 way.

Double switch in kitchen has earth, red into com and L1 and nothing in L2 at the top and black into L1 red to L2 and com on the bottom.

hope that makes some sort of sense and hope that doesnt mean pain in the ass way either !!

Albert · Posted: Tue Aug 14, 2007 4:37 pm Post Subject:

Just remember that it is very important to verify the purpose of the cables in the switches, otherwise you will find that you removed the wires from the switch connection and surprisingly one of them is still live...

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davy_owen_88 · Posted: Tue Aug 14, 2007 4:57 pm Post Subject:

Sorry, but I'm not quite following you. Could you post a photo or knock up a quick sketch with paint? All I will say is that it's good that you are getting rid of the 2-way switching because it is currently utilising the earth as a live conductor which is very dangerous.

Steve · Posted: Tue Aug 14, 2007 5:34 pm Post Subject:

Buy a 2-way dimmer

(Yes they exist, why hasnt this been suggested yet?!?!)

davy_owen_88 · Posted: Tue Aug 14, 2007 5:39 pm Post Subject:

Crafty wrote:

Buy a 2-way dimmer

(Yes they exist, why hasnt this been suggested yet?!?!)

I wrote:

All I will say is that it's good that you are getting rid of the 2-way switching because it is currently utilising the earth as a live conductor which is very dangerous.

I can't pretend I knew that at the start but perhaps I'm just psychic and don't know it yet

clupton · Posted: Tue Aug 14, 2007 5:46 pm Post Subject:

Got a sketch on paint - not sure how to post it.

2 way dimmer - ideally im looking to have a a single switch for the kitchen light and a dimmer for the front room and removing the current double switch

davy_owen_88 · Posted: Tue Aug 14, 2007 5:48 pm Post Subject:

You can upload your picture here. When it is done it will give you a couple of boxes with links in. Just copy the one with the link surrounded by [img] [/img] tags.

clupton · Posted: Tue Aug 14, 2007 6:08 pm Post Subject:

Apologies for the crappy diagram and thanks for your help

Steve · Posted: Wed Aug 15, 2007 3:55 pm Post Subject:

Not rubbishy. Seen worse! Easy.

The left switch . . .

The red that feeds both COMs should go to the COM on the new single switch. The top red in L1 also needs to go to the L1 on the new switch. These are the wires for the kitchen light.

You're left with (bottom) L1 and L2 red and black. The wire from bottom L1 simply terminate into a terminal block piece on its own (do same with black at other switch). The wire from bottom L2, put into COM on the new switch.

This should sort it if i've understood your diagram correctly!

Someone said you have an earth being used as a live conductor - i cant see where.

clupton · Posted: Wed Aug 15, 2007 6:05 pm Post Subject:

Thanks for your help.

Just a little confused about the right switch now - so on this one the black wire goes into a block. the 2 red wires then go on my new dimmer switch i have 2 connectors live and load . which one goes where?

clupton

Still following the previous instructions i wired the new dimmer up first and that worked. I then replaced the switch in the kitchen to a single switch. Now this works but the dimmer in the front room doesnt ????

Any help much appreciated

Space cat · Posted: Sat Oct 13, 2007 12:42 pm Post Subject:

You have the old fashioned type of two-way switch wiring and, no, it doesn't use the earth wire for anything other than earth.

The double switch:

That red wire in both COMs on the old double is your live feed. The red wire in L1 top is switched live for your kitchen lights. The red and black in L1 and L2 bottom are part of the two-way switching. You'll find that they are in the same cable and they go to --

The single switch:

Red and black in 1-way and 2-way are the other end of that cable from the double switch. COM is switched live to your front room light. If you've forgotten which is which, the red from 1-way shares a cable with the black in the choc block.

To make your dimmer work you will need a live supply and this can only come from the old double switch box. This is why you have to put the red from the old bottom L2 into COM alongside the one you've already got in there, just like Steve says.

Question: Does the dimmer work when the kitchen lights are on? If so, you have somehow swapped over the two reds that came from COM bottom and L1 top.

PS: Your dimmer is a two terminal device in an AC circuit. It will work either way round but --

To avoid confusion later, you should put the red wire from the old 1-way terminal into Live and the one from the old COM into Load. If you've forgotten which was which already, the red from 1-way is in the same cable as the black in the choc block.

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clupton · Posted: Sat Oct 13, 2007 1:07 pm Post Subject:

Spot on thanks very much, that all works nicely now. Thanks for your help.