I was using a circular saw to cut some 4x8 sheets of 5/8" fiberboard (not
MDF, the less dense stuff). Halfway through my first cut of the day, the
blade wound to a stop and the saw appeared dead. Checking the outside
outlet I was plugged in to I found a huge black scorch above it and half of
the plug was melted. One of the prongs melted off and is stuck in the
socket. This outlet is located outside the house but underneath a protected
entryway. The house is 10 years old and in good repair.

The saw is a 2hp 10amp. The cord is a heavy gauge (was) in good condition,
40 feet long. Not sure the exact gauge of the cord but it's thicker than
the average outside extension cord.

After this incident I plugged the saw into a different outlet (GFCI
protected in the garage) with a shorter but lighter gauge cord and proceeded
without incedent to rip my five 4x8 sheets. The GFCI never tripped.

Is a 40 foot extension cord too long to run a 10amp saw with? If that's not
it, does anyone have any thoughts on what the problem might be? Thanks for
any help.