DICEGEORGE wrote
DICEGEORGE wrote

I seem to recall reading somewhere that in 2 way switching
for house lighting its a good idea to have a neutral wire
parallel to the lives to cut down on interference, is this so?

Nope.

In which case I need 4 core and earth not 3 core and earth.
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

http://www.theiet.org/forums/forum/m...threadid=28561
says:

Paul1966

Posts: 1538
Joined: 21 December 2004

The key point is that whatever current flows in one direction along a
conductor in a
cable should also flow in the opposite direction along another conductor
in that cable.

That isnt what happens with quite a bit of lighting wiring, and it works
fine anyway.

In a single 2C(+E) cable running to a light, the instantaneous current at
any
moment in L is counteracted by an equal current in N flowing in the
opposite
direction. In a 2C switch loop, both conductors are live, but the
instantaneous
current flowing to the switch at any instant in time is balanced by an
equal
current flowing in the adjacent conductor back from the switch.

Yes, but that doesnt matter with lighting circuits.

This principle just extends to 3C cable and multi-way switching.
You might have three conductors in the cable, but for any given
combination of switch positions only two will be carrying current,
and those currents will be flowing in opposite directions.

Yes, but that doesnt matter with lighting circuits.