Electric Motors - 480 Volt Wiring
480 Volt motor wiring data - National Electric Manufacturers Association (NEMA) amps, starter size, motor circuit protection, phase wires, GND and conduit size:
| Motor HP | NEMA amps | Starter Size | Overload | Motor Circuit Protector type HMCP (ampere) | Conduit Size (inches) | Phase Wires (AWG) | GND (AWG) |
|---|---|---|---|---|---|---|---|
| 1/2 | 1.0 | 1 | W30 | 3 | 3/4 | 12 | 12 |
| 3/4 | 1.4 | 1 | W33 | 3 | 3/4 | 12 | 12 |
| 1 | 1.8 | 1 | W36 | 3 | 3/4 | 12 | 12 |
| 1 1/2 | 2.6 | 1 | W40 | 7 | 3/4 | 12 | 12 |
| 2 | 3.4 | 1 | W42 | 7 | 3/4 | 12 | 12 |
| 3 | 4.8 | 1 | W45 | 7 | 3/4 | 12 | 12 |
| 5 | 7.5 | 1 | W50 | 15 | 3/4 | 12 | 12 |
| 7 1/2 | 11 | 1 | W54 | 15 | 3/4 | 12 | 12 |
| 10 | 14 | 1 | W56 | 30 | 3/4 | 10 | 10 |
| 15 | 21 | 2 | W61 | 50 | 3/4 | 10 | 10 |
| 20 | 27 | 2 | W64 | 50 | 1 | 8 | 8 |
| 25 | 34 | 2 | W67 | 70 | 1 1/4 | 6 | 6 |
| 30 | 40 | 3 | W67 | 100 | 1 1/4 | 6 | 6 |
| 40 | 52 | 3 | W69 | 100 | 1 1/4 | 4 | 4 |
| 50 | 65 | 3 | W72 | 100 | 1 1/4 | 4 | 4 |
| 60 | 77 | 4 | W74 | 150 | 1 1/2 | 2 | 2 |
| 75 | 96 | 4 | W77 | 150 | 1 1/2 | 2 | 2 |
| 100 | 125 | 4 | W36 | 200 | 2 | 2/0 | 2 |
| 125 | 156 | 5 | W38 | 250 | 2 1/2 | 4/0 | 1/0 |
| 150 | 180 | 5 | W40 | 400 | 2 1/2 | 4/0 | 1/0 |
- 1 hp = 0.746 kW
- the equipment grounding is sized for copper conductor according section 250.122 - National Electric Code (NEC)
The grounding conductor is sized to safely carry fault current for the short time until the breaker trips - it is also sized to keep the voltage drop due to fault currents in the ground below harmful levels. The motor wiring is sized to continuously carry the full load and to keep the voltage drop at full load during start-up within a few %.
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