Will the circuit breaker in the panel qualify as the disconnect? (within sight and <50 ft). Or, can a disconnect be mounted before the conduit goes underslab?
Another issue I see is that you're going to have a heck of a time finding a suitable cover listed for the purpose for your floor box. Also, a receptacle facing up in the floor of a wood shop can't be too good a thing. A drum sander makes some pretty fine dust. Is this location subject to Article 502?
