2 way switch using 3 wire?

[Elidor]

Got a 2 way switch in a bedroom. 1 switch operates the main bedroom light and the other operates a selv transformer with a set of downlights. Bothe sets of lights are in the room. The 2 way switch is cabled with 1 x 3 wire (Blue, Yellow and Red) this single switch wire is cabled out to a junction box in the attic where the red cable is connected to the Line and used as live for both switches. Is this common / acceptable practice or do I need to run a seperate switch wire for each?

 

[DurhamSparky]

the lazy mans switch!!!

not uncommon to find..!

ideal situation would be to have independent power supply to both switches...

 

[johnboy6083]

i dont seeany problems with that. its very common to utilise one feed to a switch, and then seperate switched lives to the fittings.

 

[truckster]

As long as the JB is accessible, no problem.

 

[Elidor]

Well I was thinking if both lights are on at the same time then both circuits are being powered form the same core in the cable, kinda doubled its load. I dont know for sure what size it is ill have to check again when i go back.

 

[truckster]

And the cable coming out of the CU is carrying the load of all the lights on the circuit

 

[Elidor]

of course lol

/shutsup and hides

hehe, Thanks

 

[johnboy6083]

if your switchline is the same size as the cable feeding the whole circuit, then there is no problem. even if it is say a 1mm2, then i doubt your lights will overload this.

obviously for peice of mind, you should carry out some cable calcs if your unsure.

 

[johnboy6083]

truckster has the fastest fingers!!