I am constructing a wood working shop that is about 40 feet from my cabin in NC. The plan is to feed 240v 30amp from the main panel using 10/3 grounding outdoor wire. A subpanel will be installed in the shop with breakers for lights and outlets. The shop will contain a sander, grinder, drill press, lathe, small vacuum system, bandsaw and two fluorescent lights. Outlet wiring is planned to be 12/2 and lighting 14/2. the question is, is the plan sound and are there any suggestions for improvement?

The plan is to have the wire above ground with a post about half way between the shop and the house. How does that alter the response?

I would use #8 or even #6 copper wire for the 40 foot feeder to reduce voltage drop. This will help with the motors starting. Expect to get larger equipment later, and motors cannot tolerate much voltage drop.

Use a min of #10 green wire for the feeder equipment ground wire.

If you use UF or any kind of direct burial cable , the trench must be a minimum of 24" deep, and backfill must be without stones , rock , or debris.

Spend a bit more money on materials and use rigid conduit with THWN insulated wire, will only need to be min 6" to the top of the conduit, will save your back digging.

Now you can install a 60 amp feeder, ready for more or larger equipment. A 5 HP air compressor, a popular item in work shops, need a min of 28 running amps at 240 volt alone.

All 120 volt receptacles should be ground fault protected. You would not want to be working alone and get shocked by short in a machine.

Install a spare 1" conduit, for future telephone, data, etc.

Those are my suggestions.