150715-0959 EDT
crazybott19:
I quickly looked at the data on the WSD PDT 2P at
http://www.sensorswitch.com/OnlineCatalog.aspx?sn=WSD PDT 2P
and it looks interesting.
You need to do some bench testing. Connect a new motion sensor in the two wire mode (default) to a 100 W incandescent load. Does it work correctly?
What voltage are you switching in the circuit where failures occur? What is your load in the circuit where failures occur?
Disassemble one of your failed motion sensors. Where, around what componets, does the failure appear to have occurred? An MOV is a likely failure if excess voltage was applied relative to its breakdown voltage. MOVs are likely a round disc 3/8" to 1/2" in diameter.
Since the WSD PDT 2P apparently has electromechanical relays for the output contacts these are not likely the cause of the failue unless you switched a dead short for the load.
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