Wiring 4 gang switch

[williamglossop]

I want to change a 2 gang switch for a 4 gang switch. At the moment - there are 2 t&e cables at the switch from junction boxes in the first floor - live and switched live.

Would it be acceptable to use the 2 t&e cables as 4 switched lives? I have attached a diagram of what I propose doing. I cant get another two t&e cables into the wall, but I can get a single core cable in to provide the line in.

I have omitted the earths at the switch and would propose to wire 4 lighting circuits from two junction boxes as shown, using single core & earth to carry the neutral and earth through to the two junction boxes.

 

[ban-all-sheds]

Would it be acceptable to use the 2 t&e cables as 4 switched lives?

Yes.

I can get a single core cable in to provide the line in.

Insulated and sheathed single core, I hope, not conduit cable...

 

[sparkwright]

An alternative method may to replace one of the T&Es for a 3 core+E cable.

 

[oldbutnotdead]

The first bit of the plan (use the 2 t & e as 4 switched live) is fine with some sleeving on the black (blue) cores. Not sure where you are getting your 1 core plus e from, you can get sheathed single core which will do the job (tho t & e will probably be cheaper).

Hopefully you've only omitted the cpc from your drawing for clarity, do terminate them at the switch and don't be tempted to use cpc as L or N.

 

[williamglossop]

http://www.electricaleurope.com/Mobile/MobileSearchResults.aspx?Search=6241y

Yeah, I've shown the brown sleeving on the blue switched lives.

And yes, I'm using single core double insulated cable.

 

[SimonH2]

One thing to watch for is creating magnetic loops. OK the effect will be very small for a lighting circuit, but once you split the cables like that, there's the scope for creating a loop of cable that creates a magnetic field.*
One case I've seen was many years ago, where electricians had been working on an RFC and a conductor had come out of the back of a socket. The result was that either L or N wasn't a loop. I got called because the accounts department in the office above the shop couldn't read their computer displays at times. When the curtain fan heater over the shop door switched on, the magnetic field created made the displayed image "wobble" enough to make them unreadable.
Actually I have seen worse - when they were extending the offices they welded the steelwork joints, and used the steelwork for the welding earth return. The magnetic field from that was enough to take the image off the screens altogether

* EDIT: As drawn, the circuit from the first JB, down the single, back up a SL, and back to the N in the first JB forms a single turn coil. Current through the connected light fitting then causes an AC magnetic field.
The normal T&E switch drop has the flow and return currents in fairly closely spaced parallel conductors so the magnetic fields cancel.

 

[Risteard]

Oldbutnotdead single & earth is readily available here. However there is no need for that assuming that there is already an adequate cpc connection at the switch. Insulated & sheathed single is fine.

 

[Taylortwocities]

Insulated & sheathed single is fine.

= Double insulated.

 

[ban-all-sheds]

Oh not again...

 

[Risteard]

Insulated & sheathed single is fine.

= Double insulated.

It really doesn't.

Can you tell me what the insulating properties of the sheath are?

Thought not, because it hasn't been tested for them.

 

[Risteard]

And yes, I'm using single core double insulated cable.

Insulated and sheathed actually.

No cable has double insulation.