Mrs. S comes down from North Carolina to her 2 million dollar week-end home in Charleston SC. She calls, "No Heat" I arrive and she tells of the main 200 amp on her second panel tripping, the heat breaker sparking, and the computer upstairs doesn't work. "OK I'll look", up the stairs to the attic..... and I stand there for 5 minutes wondering why I am not standing in a bed of coals.
A cheap plastic disconnect was attached to the joist and burnt off, all that's left is the wires and the lugs. It looked as if one of the lugs cracked and sparked.
The wood behind the box was acctually charred 1 inch deep. Why it didn't burn I'll never know.
I serviced this unit in January and checked the connections all tight. My former employer did this install three years ago. Then sold me a portion of the company. This was one of them. I remember thinking at the time of the install, "these are cheap disconnects" and "the electritions are off duty firemen so I guess they are OK". Not again, they get switched or no start up.
Here is the box
got the attic light wire too, thus no computer power.