Switch wiring

[SimonPaulH]

I have a double light switch socket that I want to replace. I’m happy and competent (and have) to replace basic single switch/sockets but this one is giving me a problem.

Inevitably the switch I’m replacing and the new one aren't the same. The original has 2x common nodes, and L1, L2 and L3.

The new switch has two blocks, each with L, L1and L2.

Obviously Common=L, and L1/2/3 would be matched.
However, there’s a bridge wire in the old switch between one of the Commons and L3. I don’t understand why, and in any case there’s no L3 on the new switch.

see images below

appreciate any guidance here. Thanks in advance

Simon

 

[JohnD]

the new switch is actually easier to look at and understand.

The double switch contains two switches.

Each switch has three terminals, arranged in a triangle. This is because it is a 2-way switch. Wih the tumbler in one position, the electricity comes in* through the single point at the point of the triangle, and goes out through one of the other two. With the tumber in the other position, it still comes in through the point, but now goes out through the other terminal at the wide end of the triangle. It does not matter if the terminals are marked L1, L2, L3; or Com, L1, L2; or 1, 2, 3. They are always constructed with three terminals in a triangle.

In your old plate, one of the triagles is pointing up and the other is pointing down. In your new plate, both triangles are pointing up. but the functions of the terminals at the point, and on the base, are the same.

When you do not need two-way switching, you just use the terminal at the point of the triangle; and whichever of the other two takes your fancy.

* "in" and "out" are notional terms.

 

[SimonPaulH]

Err….ok, thanks John
One switch is for an outside light (actually it’s in the porch), and is the only switch for this light.
The other switch is one of two in the hall for the hall lights

So if I understand correctly, for the two way hall switch I wire one block/triangle on the new switch L, L1 and L2 and the other for the porch light will just be L and either L1 or L2 - I shouldn’t need the bridge wire?

And because I don’t know which wires coming out of the hole do which light, and I’m OCD and want the switch nearest the door to doe the outside light, if I get them the wrong way round I can just swap them over?

 

[JohnD]

I should think the bridge wire is to take power, from the hall light circuit, and provide it to the porch light. That might have been done if the porch light is a later addition. it looks to me like the porch will be the right-hand switch in your pic, because the cable with just red and black is single switching, and the cable with red, yellow and blue is 2-way switching. I can't see where the black one goes.

As you have so many wires, rather than take them all out and reinsert them all (giving room for error) you can just turn the switch over. This will swap left for right.

If the switches and lights work as currently wired, copy all the wires from the old switch to the new one, allowing for the fact that the triangle on the right is upside down. it is a good idea to mark each wire with a fine permanent pen, such as a Stabilo, before you disconnect them.

Draw your own diagram, and call the terminals "Point" "Base 1" and "Base 2"
if you have the triangles correct, it doesn't matter what the markings say.

OOI, does the porch light go out when you turn off the hall light?

 

[SimonPaulH]

Thanks again John
No the porch light is independent of the hall lights

 

[SimonPaulH]

Here’s another shot from a different angle. The porch side switch is on the right as you look at the back of the switch.
So it looks like I’ve got a red to L1 (top right), the bridge from common to L3 ((assume hall switch). Black and yellow both go to L2 and two more reds to L3

 

[EFLImpudence]

So it looks like I’ve got a red to L1 (top right),

Yes. L1 Right switch in new switch.

the bridge from common to L3 ((assume hall switch).

No, it is from L3 to Common.
New L1 Left switch to L Right switch.

Black and yellow both go to L2

New L2 Left switch.

and two more reds to L3

New L1 Left switch.

Just a straight copy but turn the Right switch upside down.

 

[SimonPaulH]

Thanks!

 

[winston1]

Don't forget to put the earth wires (all 3 of them) into the earth terminal.

 

[SimonPaulH]

Don't forget to put the earth wires (all 3 of them) into the earth terminal.

In the current - original old switch - the earth wires are wired into the socket box? Are you saying I should change that and wire them into the switch instead?

 

[EFLImpudence]

Yes, now you have a metal switch.

Just a wire from back box terminal with the other earth wires to the switch would be alright.

 

[SUNRAY]

Doing it this way the shoert red wire can be reused.
In the pink square nothing changes.

 

[EFLImpudence]

D'oh. You'll confuse him now.

 

[winston1]

In the current - original old switch - the earth wires are wired into the socket box? Are you saying I should change that and wire them into the switch instead?

I was saying that but as EFL says an additional gr/ye wire from the backbox to switch is also OK.

 

[SimonPaulH]

Ok thanks all for your help and advice