Numerous possibilities of interference. In my experience, these are not a problem, since the designer has to worry about interference levels that could induce false triggering and instability. All the circuits I have seen use solid state switches to turn things on and off. Proportional temperature control is used. There may be contactors in each of the 2 refrigerant pump circuits, but they only cycle if the on-line one fails.
All circuits are in conduit.
A several line bus at 120 volts ac is used to control this zone lighting, each zone having contactors as indicated above. There are several automatic power switches, and 1 manual switch. These are not likely to be a problem, but in any event the power transfer contactors have snubbers across the coils. Automatically and manually adjusted to keep adequate load on 600 kw generator. This is done with a number of fixed resistors which are switched in and out by relays.