Em Lighting key switches!

[Crosswire]

OK,
Settle this once and for all please chaps.

When keying off emergency lights, should you switch;

1) just one pole (e.g. the permanent live)
2) two poles ( e.g. both switched and permanent lives)

or

3) three poles ( both lives and neutral also (as some key switches have two poles) ) ?


Thanks

 

[Des 56]

Is here is a mesage here