Re: Exterior egress lighting
In my area most want dual lamps. Weird thing is that they are ok with a two lamp fixture with one ballast. IMO that doesn't meet NEC.
As for monitoring the interior or exterior lighting, I don't monitor the interior circuits to determine when to cut on the exteriors. Code requirement is that emergency fixtures be supplied from the circuit that supplies the normal lighting for the space. IMO interior lighting is not in the same space as the exterior lighting.
"In this house, we obey the laws of thermodynamics" - H. Simpson.