Cantex recommends a 1/2" O ring
We do not make these in metal.
This is a schedule 40.
An unequivocal maybe. The question is does the "standard" (no such thing) 30 amp disconnect have a 3/4" knockout available. Most disconnects have multiple KOs (1/2, 3/4, for sure and sometimes 1" and larger). It just comes down to size and how many.
That's what it's made for.
This should be 3/4 inch mpt.
If it on the bottom or side of the box, none is required. On the top, you may want to use an o-ring to seal. Anything that fits over the threads will work.
This product can be used with both Schedule 40 or Schedule 80 conduit.
If coming from the outside world to the inside world why not? Check your local NEC and find out what version the inspectors use at your building dept..
3/4" standard ko fittings. Or if useing a hole saw I drill a 7/8ths hole and add wd40 for easier installation...