While drilling through drywall in bathroom to install a handicap bar to studs, I later discovered that the microwave oven breaker had tripped. Apparently one of the drill holes had missed a stud and went through PVC pipe in the wall (this was determined later with a tiny scope camera inserted through the drill hole). Although the microwave has been working fine after resetting the breaker, not sure if I should open up the wall to examine or wait and do so only if the microwave breaker trips again. I'm assuming that the breaker would trip before any potential fire might occur due to compromised wire.
I must say that I am very puzzled that there might be wiring to the microwave using electrical PVC conduit instead of cable! I live in California and the house was built in late 1980's. I thought California code called for cable for all electrical wiring within the walls!
The paragraph in italics has been revised. I've attached a photo of the conduit and it doesn't appear to be electrical pvc conduit after all. It seems to be much smaller diameter, 1/2" or so, and possibly not rigid. Hope this helps!