I am not aware of how the Canadian codes treat what we call "multi-wire branch circuits,' or, less formally, 'shared neutrals.'

This is the practice of running a three wire cable from the panel to the first junction box, where the two circuits are separated. Thus, they both use the same neutral for the final run back to the panel.

For such a circuit, the GFCI or AFCI breaker must, necessairily, control both of the 'hot' wires; thus the need for a two-pole breaker.

Here the more current issue relates to a design change in the AFCI's themselves .... no point opening that can of worms here!

It's also not unusual for the room air conditioner or baseboard heat to be a 240v circuit.

Last edited by renosteinke; 07/06/09 03:03 PM.