2way light, 1 way light, merging into a pair of 2way

[measureitonce]

Next daft question of the day

I've knocked two rooms into one and at present have two seperate light in the same room. I want both ceiling roses to operate together on 2way switching.

Ceiling rose1 is wired as a 1way to a 2gang 2way switch at the bottom of the stairs (the other gang of the switch is wired 2way for the landing).

Ceiling rose2 is a 2way. one switch near the front door, the other now in the middle of the room where wall used to be.

My thinking is, remove the switch wire from rose1, replace wire from rose2 to the switch in middle of room, and take it from rose2 to the 2gang switch at the bottom of the stairs rechasing as needed. That gives me Rose2 working 2way at the correct switch locations.

How do I then incorporate Rose1 in the mix? Can I just take wiring from rose1 and put it all in a JB, and run T&E from rose1 back to rose2

many thanks

 

[ericmark]

Yes can be done but no you shouldn't do it.

Many years ago electricians would borrow line feeds from another switch to get two way switching from a pair of wires. However this means the supply and return don't take the same route and as a result it transmits 50 Hz giving HiFi, radios and TVs mains hum. It also often means you end up with borrowed neutrals which is against the rules and dangerous.

As to how depends on how already wired.

In general we use three core and earth cable for multi-switching. And the wiring goes switch to switch not lamp to lamp.

So orignal two way switching will have one switch with 5 wires and one with 3 wires. The switch with three wires is swapped for an intermediate switch the wire originally going to com will go to a connector strip and to same colour on new cable. Other four through new switch. New cable goes to old switch connected as before.

 

[measureitonce]

Great info thanks.

I hadn't realised about the switch to switch bit, I thought it was all done at the rose like a 1way. I have now verified that the switch I need to move is the one with 3wires. Can I simply join and extend this to the other switch position, or better to replace complete run switch to switch with a longer length?

How do I go about incorporating the 2nd rose? simply connect to the other rose with length of t&e? and use a jb to join the ring back together where is was connected in the rose?