Thanks Ned,

I am not sure it was an over-pressure though and the compressor was
still running above the reset point of the relief. It wasn't until I
turned off the power that a few seconds later the pressure relief
reset. If that's what it is supposed to do. It may just be a faulty
pressure relief valve that suddenly decided to open.

The pressure relief's reset point is lower than the compressor can
maintain pressure when the relief is open and that's why it was still
running. Maybe I need a different pressure relief. I bought the
compressor new back in about '98, so I know it is the factory fitted
relief.

Maybe I need both a switch and relief. I don't have mnoney to just toss
at it so replacing the real culprit is important.

Dave