2 Separate Lights with 2 Way switching on one

[jmwhooper]

I have some new switches to replace the tired old switches in the hallway and upstairs landing. The downstairs switch is a 2 gang 2 way, upstairs is 1 gang 2 way. I've looked at the existing wiring and am wondering if someone can fill in the blanks based on the diagram below, I'd like to understand more about the layout before changing the switches like for like.

The lighting is wired using junction boxes. Do the wires labeled A1 and A2 join to each other? Do B & C go to the J-boxes and where does the ? go. I've left the earth wires off for clarity.

Thanks in advance

 

[ColJack]

cable B brings power into the switches, and takes a switched live back to the 1 way light..

cable A is the strappers for the 2 way..

cable C is the switch wire to the 2 way lights..

A1 and A2 are the same cable

the ? goes nowhere, they used T+E instead of singles..

 

[jmwhooper]

Wow thanks for the quick reply.

So on Cable B the Red wire to the Com would that be the power and the black to L2 the switch live, or visa versa?

Thanks again

 

[ColJack]

sorry, i'd gone to bed by then...

yes, red is live, black is switched live ( should have red / brown sleeve on it ) that's why they used black out of cable C..

generally, anywhere you see a wire linked across several terminals ( as in you drawing ) then that will be the live feed..

 

[plugwash]

this method should only be used if the lights are on the same cuircuit but its not that uncommon to see it done between cuircuits (so watch out!)

in your case rather than using a single red for the final run to the light they've used the black core of T&E. The red core of the T&E may have been left floating or been connected somewhere depending on who did the installation. Best practice for unused cores is to tie them to earth but make sure its not tied to live at the other end before doing that!