Dimmers and 2-way circuits

[MCrook]

I know that this is a common topic but I am still having problems after reading the other posts. I have moved into a new house a couple of days ago and am in the process of fitting a couple of dimmer switches for the lights. This is where the problem starts.

I went to change one of the 2 two-gang Hallway and dinning room switches with a 2 gang dimmer (there are 2 two-gang switches one in the hall and one in the dinning room). One of the dimmers appeared to be OK, with a single common, L1 & L2 wire. The second dimmer had a common, a two red wires in L2 and a red and a blue wire in L1. The position of all the wires were copied from the original switch. When the power was turned on the Hall stays on no matter what position any switch is in and the dinning room works fine.

When the original two-gang switch was in place, all four switches (two two-gang, one in the hall and one in the dinning room) could operate both lights.

Also, when the dimmer for the Hall is turned on it makes the living room light flicker (new dimmer fitted).

Any Ideas on how to get the dimmer to work on the 2-way switches?

 

[breezer]

i had to read your post several times, am i missing something, but what is in the common?

you said "The second dimmer had a common, a two red wires in L2 and a red and a blue wire in L1." but you have not mentioned the common

 

[spark]

Breezer, I think he must have yellow in the common. If he's got a blue it would make sense that he has a yellow; he must have a twin red+earth and the three core in between the switches.

If you changed it exactly for how it was I don't see you should have any problems. If you have got yellow as the common, just check to see that yellow is connected to common the other end.

In agreement with breezer, your description is not very clear. Are you saying that you have a hall light controlled from both the hall and the dining room and a dining room light controlled from both the hall and the dining room? You haven't tried to fit a dimmer at both ends have you? Somehow you've got the hall, dining room and lounge all involved with a number of switches. Try to rewrite the question so we can understand the installation better.

 

[MCrook]

First of all thanks for the replies. You are right in what you say, in that the hall is controlled from both the hall and the dining room and a dining room light controlled from both the hall and the dining room.

Switch 1 (in dining room) fitted with dimmer:
Common = Yellow
L1 = Red & Blue
L2 = Red & Red

Switch 2 (in dining room) fitted with dimmer:
Common = Yellow
L1 = Red
L2 = Blue

Switch 3 (Hall) fitted with existing on/off switch:
Common = yellow
L1 = Red
L2 = Blue

Switch 4 (Hall) fitted with existing on/off switch:

Common = Yellow
L1 = Red & Red & Red (I did mean to put three red wires)
L2 = Red & Blue

I labelled all wires and took digital photos of all switches before doing anything.


With the current set up:
Switch 1 does not appear to do anything except when turned on makes the living room light flicker. The living room has also been fitted with a dimmer. This had Common = Red, L1 = Red & L2 + Red.

Switch 2 turns on/off and dims the dining room.

Switch 3 does not appear to do anything to the light although when testing the live wires they switch between L1 & L2 when turning the switch on/off.

Switch 3 does not appear to do anything with the number of wires just confusing me.

Also, the Hall light is permanently on no-matter what position any switch/dimmer is in.

Finally I did try replacing the new dimmer (switch 1 & 2) with the old switch and although the light do all go on and off it is not in a logical order with both the hall and dinning room being capable of being turned on/off from any of the four switch depending on the sequence that they are pressed.

I hope that this is a better description, apologies for the last one as it had been a long night and early morning. I hope that you may be able to help.


[/quote]

 

[spark]

You appear to have an extra red at switch 4...hmmm. I'm assuming switches 1 and 3 are supposed to control the dining room lights and switches 2 and 4 are supposed to control the hall lights?

You've also got 3 red cables at your lounge light switch...now either it's all wired in conduit with singles or someone has done some wiring that's not quite in keeping with the norm...Are you sure it's not just red sleeving over a yellow, blue or black cable?

If you've just moved in, can you be certain that it was all working absolutely perfectly before you took it all apart? Either it was wrong in the first place or you've made a mistake somewhere; 2-way switching should not be conditional on the state of the other switch positions.

If it was dodgy from the word go then I would seriously consider getting it looked at by someone who knows what they are looking at. Even then it may take them some time.

Post the photo's on here if you can or e-mail a copy to me (and breezer might not be a bad idea if he doesn't mind) and I'll see what I can see.

 

[MCrook]

Cheers for the help with this one, but I managed to sort it all out. I managed to get a multimeter and a reel of wire and tested each wire individually. Then using a wiring diagram from the web rewired all the switches, including the living room. I have got no idea how they worked at all before I did this as the wires between the switches were mixed up.

The lounge light was just three red wires, A live feed, a feed to the light and a loop to feed a live wire to switch 1. All the others were just muddled up. The switch with the three reds was a live feed, a feed to the light and the extra red I believe either feeds a live to the smoke detector or looping a live to another lighting circuit. I will have the fun of finding that out when I start to look at the other circuits in the house.

Once againg cheers for the help and the offer to look at the photos.