In article , Richard J Kinch wrote:
Everything seems fine right now, until I throw the disconnect on, at
which point it arcs at the main GFI in the house and trips the breaker
and disconnect hard.

Something to check: a half-high double-pole breaker on the wrong spot in
the panel creates a dead short.

How?

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Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?