2 gang 2 way light switch adding extra switch?

[Mike2512]

Hi there,
I’ve just moved into my first Home and I’m not bad at diy but electrics isn’t my strong point.
In my garage I’ve got a two way two gang switch, one switch controls outside light and the other controls the interior garage lights. I want to put another switch at the other end of the garage for the interior garage lights only but when I took the switch apart the wiring was not what I expected.
The existing double switch has only 3 wires going to it;
Black wire to L2
Yellow wire to other L2
Red wire to Common
And a red link wire between two commons.

Both L1 terminals are empty.
To wire in another switch where would I need to put the new cable, I’m assuming one in L1, one in L2 and One in the common of the switch I want and then of course the earth but I just wanted to make sure before I do this?
Any advice would be greatly appreciated.

 

[EFLImpudence]

Which is the garage switch? Black or yellow wire?

 

[Mike2512]

I think black is the interior garage light

 

[EFLImpudence]

Do you realise the two switches are two triangles, one inverted, NOT the three terminals at either end?

Is the answer still black?

 

[Mike2512]

Yeh I read that, sure the black wire is for the interior light. Yellow is the outside light

 

[EFLImpudence]

Ok. You need to move the single red from COM to L1.

Then run a 3 core and earth cable from this switch to the new switch.
Connect one core to each terminal, it doesn't matter which, along with the black and red already there.
Ensure you connect the same colour to COM at old and new switch. Other than that the colours don't matter.

 

[EFLImpudence]

You should end up with this -

 

[Mike2512]

Excellent thanks for your help.. I’ll give that a go in the morning and let you know

 

[ban-all-sheds]

Mike, when you look at EFLI's diagram, do you understand it, know what's going on inside the switches, and know why the whole assembly does what it does?