Is this possible?
Cassetta switches in a 3 or 4 way switch config. with two wireless motion/occupancy sensors.
Use:
Entranceway stairs leading to a hallway with a 90 degree turn at top of stairs, then 15' of hallway to another set of stairs (these are parallel to the hallway direction)
Switches: One at entrance way, one at top of second stairway, and a third (possibly) at an intermediary point between.
Thanks in advance