Light switches

[Dave]

My wife and I went down to our son's house today so that I could continue to remove light switches from behind open doors (at the hinge side) to the other side, so that they can be switched on upon entering the room.

However, I have come across something that I have not encountered before.

Task to perform, is to transfer the kitchen light switch to the lounge. As above, you have to enter the room, close the door and switch on the kitchen light.

Kitchen light switch is back to back with a second light switch for the lounge. This is a switched dimmer. If memory is correct, it worked from red and black as input/output.

Wires that come into this are yellow, red and black.

The yellow has been isolated and wrapped with sellotape. The red is live and the black (un sleeved) looks like being the feed to the lounge lights from the dimmer switch, as it varies the voltage, depending on where the dimmer switch it set to.

At the kitchen side of this, the light switch is a single pole double throw switch.

Looking from the back of the switch, it has 3 connections. First one is top centre. The others are bottom left and bottom right (SPDT) As it had wires going into all 3 points, my first instinct was to find a second light switch in the kitchen, but both my son and I can not find one.

Top centre has a red wire from it and is live when the kitchen lights are lit.

Bottom left has a blue and black wire that become live when the kitchen lights go on.

Bottom right has a yellow and a paler red wire to it and it is live all the time.

All measurements were taken from earth.

Any ideas anyone?

Dave

[cj]

Hi Dave sounds like you have a 2way switching circuit. You probably have the following :-

1 cable red & black wire (plus earth) going to the light 1 cable red blue & yellow wires (plus earth) heading off to another switch in the kitchen/outhouse/garage etc.

Look for another entrance to the kitchen and try and find a switch or a freshly fitted cupboard hiding one.

If you are sure this does not exist try this.

Turn off power. Remove yellow and blue cables from switch along with the red wire in the top . now take the black wire (bottom left) and put it in the top hole. Turn power on and try the light. If the switch works but is upside down either turn it over or move the red wire from bottom right to bottom left.

as always if you are not sure don't try this get help.

HTH

CJ

[chrisj.doran]

Also signs of a removed pull-cord switch in the ceiling.

Chris

[Dave]

Thanks, I never thought of that.

Dave

[Dave]

That was my first instinct. But I couldn't find another switch.

I can't visualize that, so I will draw it out, so as to get it into my mind. I work better with a circuit diagram.

The only other door is from the back garden and there is no sign of a switch either side of it. That is not to say that there is not one though, so I step with caution.

I'll draw that out as well :-)

I am very confident in my skills with wiring, it was just this strange set up that caused me to step back a bit. I have, in the past, had to work on live wires and I took all the steps to prevent me from killing myself. I am still here :-) If I start to work deep into the wiring, I will get a 3 amp in line fuse into the permanant live until I get to the bottom of this problem.

Yes, it did thanks.

Where does the yellow cable come into this? Also, why a paler red?

Dave

[John Rumm]

Yellow is usually a wire from a three core and earth - historically yellow, red, and blue (same colours as three phase). These days brown, black, and grey. This cable is routinely used for two way lighting control, or any situation you need to carry neutral, live, and switched live in the same cable. See piccy:

paler red is probably just red, but from a different make of cable, or one that has faded a bit over time.

[Dave]

Many thanks for that John. I was aware of the yellow cable but I failed to connect it to a two switched system, as there was no evidence of another switch. I'll take a closer look when I am down at his house (35 miles away,) so it will be a few days before I get back to this problem.

Dave

[Dave]

Having drawn that out, it is clear what you are talking about.

Many thanks

Dave