The original post stated exit signs and exit lighting. Unless "exit lighting" means "emergency lighting", this is fine.
Even if the exit signs have "frog eyes", those emergency heads will only illuminate the exit area itself upon a power failure, local or general.
There is no logical reason they can't be on a separate circuit.
That being said, I almost always connect them to the "night light / path of egress emergency lighting" circuit.
In buildings without emergency power, I always try to connect the switched lighting circuits of electrical, mechanical, and communications rooms to these circuits as well, should the owner ever decide to add a generator.
Even if the exit signs have "frog eyes", those emergency heads will only illuminate the exit area itself upon a power failure, local or general.
There is no logical reason they can't be on a separate circuit.
That being said, I almost always connect them to the "night light / path of egress emergency lighting" circuit.
In buildings without emergency power, I always try to connect the switched lighting circuits of electrical, mechanical, and communications rooms to these circuits as well, should the owner ever decide to add a generator.