Is it permissable to group two or more 3 phase air curtains on one feed? In addition to a blower they of course have a heating element. Also being as the only control is a three position rocker switch with an off position is a disconnecting device required? Thanks

I would think "why not"? So long as your with in the ckt limitations.
As for the disconnect: So long as it is within site of all three, and meets the load requirements. Why not?

In a nut shell, yes and yes.

Rule 28-600(3) permits having more then one air curtain on a single disconnecting means.

Rule 28-602 describes what is permitted as far as a "disconnecting means" is concerned, and no, a three position selector switch is not adequate.

Rule 28-604(5) requires that the disconnecting means be located within 3m of the equipment and in clear sight. I would consider this equipment to be "air conditioning" equipment because of the heating element.

Rick...