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- Feb 1, 2015
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The hole appears to be directly over one of the switch contacts. If, for some reason there was an electrical arc inside the switch that burned through the Balelite and pierced the metal on the switch, it shouldn't have gone any further. The switch should have been grounded to the box by virtue of its mounting screws and the arc would have gone to ground. I can't see how it would continue to make a hole in the cover plate.
A more likely scenario is that a hole was drilled in the cover plate and the switch providing a path to ground and possibly damaging the electrical circuit within the switch. I have seen something similar with a lightning strike where lightning came down a television antenna lead and blew a half dollar sized hole in a breaker box. There was an associated fire that totaled the business though.
You didn't say what type of pump you had. If it is a deep well submersible, they are an excellent earth ground and attractive path for a lightning strike. I would agree with Flyinfool. A pump should have a dedicated circuit.
A more likely scenario is that a hole was drilled in the cover plate and the switch providing a path to ground and possibly damaging the electrical circuit within the switch. I have seen something similar with a lightning strike where lightning came down a television antenna lead and blew a half dollar sized hole in a breaker box. There was an associated fire that totaled the business though.
You didn't say what type of pump you had. If it is a deep well submersible, they are an excellent earth ground and attractive path for a lightning strike. I would agree with Flyinfool. A pump should have a dedicated circuit.