Smart Switch Wiring Help

[bash247]

So I've changed many switches in the past with no issues as the number of wires is usually simple to work out but in my recent home, I opened up the socket to replace it with a Sonoff T3-Black and it's completely baffled me with the amount of wires I saw behind it.

In the living room there are two lights which are controlled by the switch I'm trying not replace. On the other side of the room there is another switch that only turns off one of the lights.

Here is the back of the current light switch and the wires.

(Top brown is Common, Left is L1 and right is L2)

Now for the smart switch, I have the Neutral wire (blue, currently not in use) and live (Common wire in old socket). The remaining output is L1 out. Do all the wires go in that? Surely not.

Diagram for the smart switch below.

Thanks

 

[bash247]

are you wanting to keep the other switch or make it redundant?

its wired for 2 way switching so there will be a 'strapper' that goes from there to the other switch

I would like to keep it functioning the way it is personally. The lighting can be bright at times so turning one off is handy.

 

[bash247]

As you enter the room there's a switch that controls two lights (left & right)

On the other side of the room, there's another switch that only switches on/off the left light. If you were to go and turn off the left light using the secondary switch and go back to the main switch and try to turn the lights off. Both lights would "sync".

I tried the wiring today and planned to make the secondary switch redundant for now. Will need to buy a spacer as the switch doesn't fit

 

[bash247]

So I come into the room, turn the lightsswitch you pictured on, and on comes lights A and B, if I go to the other switch and flick it, light B turns off, but not A?, but if I then go back to switch 1 and turn it off, light A goes off and B stays off, if I flick it again both lights A and B come back on?

Sounds most odd, does the reverse work? I.e. use switch 2 to turn on light B and then switch 1 brings light A on as well, but then if you turn switch A off, both go off again?

Can we have a picture of the wiring in switch 2?

This sounds the most accurate. I will open the 2nd switch and show the wiring. I managed to use a spacer to screw the sonoff switch to the wall to hide the exposed wires.

 

[bash247]

Common in that switch isn't your feed. Judging by the the two cables coming in the right hand side that would be your feed in and out and supplying the permanent feed on the grey core and thus your brown with the black core is the cable going to your light(s)

So basically you need the two browns that go with the grey to go to your L in and the other brown that's with the black goes to your L1. The other cores on the three core (brown/black/grey) can be put in connector and left. Don't cut them out.

It's called the Dundonian two way up here because it saves you running an extra cable from the furthest away switch up to the light. This method you take everything to one switch instead.

Mocked up a quick diagram so you can see what I mean.

Should there be more than one image? I can only see one them

 

[bash247]

Apologies for the lack of update but work has been extremely busy. The photo below is the wiring for the second switch.