I want to add a security light to the outside of my garage. I have a single light switch which I would like to change to a double switch- one switch for the security light and the other to remain for the inside garage light. How do I wire the new double switch? i have managed to feed a lighting cable identical to the ones already there down the conduit to the switch. At the moment 2 cables go to the switch and can be traced back to a main box with trip switches. cable 1 has one red wire connected to a COM point (i presume live) while the neutral is linked to the neutral of the other cable via a little block. the earth wires of the 2 cables are aso linked together at the little block. the red wire of the 2nd cable is attached to a L1 point on the switch. My cable is at present taped up and not being used. 