Wiring 2nd light from one switch

My first post so forgive me if it's already been covered.

I have two landing lights in the house. One works fine, the other doesn't work at all, and never has since we moved in. After a bit of investigation I've discovered:

- the light that isn't working has three (red, black and earth) wires going to the rose, one of which heads (in the loft) in the direction of the switch on the landing, but doesn't get there, instead it finishes at a round junction box with no other wires going in or out (dead end).

- I can't see a way of extending the wire down to the switch as the current wiring to it the appears to have been plastered in rather than running through a conduit.

- the 'loop in' section of the rose is live, which I assume means it is wired into the lighting ring.

- the switch on the landing is a double, the left switch turns the working light on and off and is wired to be a two way switch with the other switch in the hall downstairs. Having opened it up I can see that there is only wiring for one light.

My question is, can I break into the switch wire for the working light and, through a junction box, connect the second light or will this cause a problem as they are both wired into the ring?

I completely rewired our first house, so not a complete electrical virgin, but would understand if the advice is "call in a professional".

Any help gratefully received.

Can't you just take it off the existing working landing light?

breaking into the switch wire will not work....unless by some sheer fluke it is wired in 3 core and Earth and the third  wire is a neutral

I think you mean you have 3 cables going into the non-working light, loop in, loop out and switch cable. It is the switch cable that is terminated in the junction box. So it should be possible to connect the switched live of this cable to the switched live of the working switch cable. But they must be fed from the same fuse or circuit breaker, they should not be fed from different circuits nor should the neutrals be shared from different circuits.

Thanks for the quick reply Rob (and Kerching); yes, you're right, there are three cables (each having red, black and earth wires) going into the non-working light.  The upstairs lighting all comes off the same circuit breaker at the consumer unit.

I guess the worst that can happen is the circuit trips when I turn it back on?

Have you got any test kit?

HPGrover said:

The upstairs lighting all comes off the same circuit breaker at the consumer unit.

Click to expand...

But is the 2 way lighting fed from upstairs or downstairs? Switch off the upstairs lights at the breaker, does your working light ( the one you are taking switch live from) still work?

I don't have any test kit, but can buy if needed.

The working light goes out when I switch off the upstairs lights at the breaker.