I have a single 30A 240V circuit run in my shop right now, and I share it by either plugging in my Unisaw or my air compressor. Both have 10 gauge wire going into the tool and were wired that way when I got them. The wire from the panel to the socket is 8/3. The Unisaw is a 2HP unit and the compressor is a 5hp.

I never run them simultaneously, but it would be nice to leave them both plugged in all the time. Is there a problem with multiple 30 amp receptacles on a 30A 240 branch circuit?

This is in a building that was built in 1975, so its all old work.