I never thought it was legal to combine neutrals. I assumed it happened occasionally in those octopus ceiling boxes and gang boxes with 5 switches in them but I thought AFCIs stopped that stuff.
I do think grouping neutrals in multiwire circuits, along with the other ungrounded conductors is a good idea. A tywrap does that.
I guess a related question is how do you identify the neutrals if you have a few ungrounded conductors with 2 or more circuits? Is it legal to put a wrap of colored tape on the white wire to identify it as going with a like colored ungrounded conductor?
