On one circuit breaker I have a manual switch. On the second circuit breaker I have a motion sensing switch (using a mechanical relay). I have a number of lights wired in parallel as the load. The lights should turn on as a result of motion or manually turning them on. Unfortunately I can't just wire the two switches in parallel on the same breaker because of physical constraints; I'd have to perform a major renovation to rewire.
It seems I need a sort of DPDT relay like this, which is normally open, has two magnetic coils, and keeps both circuits separate:
Does a relay like this exist? Is this the correct way to solve this problem?
Best Answer
Use a simpler relay
A better plan would be to use a UL-listed SPST relay with a 120V coil driven from the motion sensor, with its contacts in parallel with the lightswitch. (A Functional Devices RIBU1C or RIBU1S will do the trick, provided your lighting load does not exceed 600W.) That way, all your lighting is powered from one breaker, and you don't have to do a bunch of rewiring.
Of course, this requires that your motion sensor power itself through the neutral, or be replaced with one that does, instead of "cheating" and trickling power through the load.