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J IA, First of all you definitely wanna go with 240 volts if the motor is a dual voltage 120/240 or more likely a straight 240 volt for a 5 HP. Thats a decent sized motor for single phase application you know. Next, Ugly's Electrical Refernces Handbook lists 28 amps as the full load current for a 5 HP Single Phase Motor at 230 V. Sooooo assuming its a 240 volt single phase motor I strongly suggest you use 8/2 with Ground (3 conductors, 2 insulated phase wires plus a bare or green insulated equipment ground) Type UF (Underground Feeder) Cable. Unless its a very long run (how far is it???) in which case you might need larger gauge wire to reduce voltage drop, but at 28 amps the 8 Gauge ought to be adequate for a long distance. NOTE: I would NOT try n get by with 10 Gauge Wire..... .... Once you get to the Motor I would use a 2 pole (NEMA 1 Enclosure if indoors NEMA 3R if Outdoors) Safety Switch Disconnect right at the motor but at worst case in sight and within 50 feet from it. You can choose either a 2 pole fuzed or circuit breaker type of Safety Switch Disconnect for the Motor, and if a fused you might get by with a dual element time delay (Slow Blow) fuze or perhaps a 40 amp circuit breaker since motor start up current (approx 6 x run current) might trip a 30 amp breaker. You are permitted to size a motor service circuit breaker at a higher current rating then the Motors Full Load Amps (28) in order to allow for it to start as the Motors Internal Thermal Protection Current Overload (assuming it has a thermal overload protector) ought to trip out to protect the motor if she overheats or overcurrents. In the event the motor had no internal thermal overload protection, then you should use a regular motor combination starter (disconnect plus overload protection) to provde the disconnect PLUS overload protection. See if the motor has some sort of red pushbutton type of thermal overload????? I would use a Rigid Conduit riser up out of the ground to the Safety Switch and then use watertight flexible conduit (Seal Tight) from the Safety Switch to the Motor. Dont forget to bond the bare/green safety equipment ground to the safety switch and conduit and the motor itself. NOTE: I been retired a good while and am rusty on the NEC and havent kept up but believe most of the above to still be accurate but NO WARRANTY LOL Best wishes n God Bless John T Retired Electrical Engineer in Indiana
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