On Mon, 5 Feb 2018 17:11:32 +0000
John Rumm wrote:

On 05/02/2018 16:19, Steve wrote:

It can get interesting when the up and down circuits share a
neutral, generally on the landing light.

Yup, although that in itself is a fault that should be fixed since it
brings a shock risk all of its own.



Yeah, a Code 2 (page 14):

https://www.electricalsafetyfirst.or...ce-Guide-4.pdf

Often not discovered until you attempt to put the circuits on separate
RCDs.