usually if its under 1 amp don't worry about it, it counts as a single device on the circuit so 15 amp breaker could have up to 12 (1amp) devices, 80%, such as resi, in comm wiring usually its only 8-10 devices, yes I have seen prints were the bathroom fan was called to be on it's own circuit the as builts showed it was put on with the lighting provided it wasn't 347v lighting of course.