Final answer:
a) Yes, the NEC does allow a 2-pole switch to be used as the disconnect for a 3.3 KVA, 240-volt, single-phase air compressor as long as the switch is properly rated for the load.
Step-by-step explanation:
The National Electrical Code (NEC) does permit a 2-pole switch to be used as the disconnecting means for a 3.3 KVA, 240-volt, single-phase air compressor, provided that the switch is rated for the load. The disconnect must be capable of breaking the load current of the air compressor, which includes both the running current and any additional current from starting or stopping the equipment. NEC states that the disconnecting means for motors must have an ampere rating of not less than 115% of the full-load current of the motor it serves. As long as the voltage and current rating of the switch are both adequate for the air compressor's requirements and it is accessible to the users, it would be permissible to use the switch as the disconnecting means.