3 HP Motor Amps — Full-Load Current, Wire & Breaker Size
Full-load current of a 3 horsepower motor at every standard voltage, with minimum conductor size and maximum breaker and fuse ratings worked out for each.
A 3 HP motor draws 9.6 A at 230 V and 4.8 A at 460 V three-phase; 34 A at 115 V and 17 A at 230 V single-phase.
3 HP three-phase motor
| Voltage | Full-load amps | Conductor ampacity (125%) | Min. copper wire, 75°C | Max. inverse-time breaker (250%) | Max. time-delay fuse (175%) |
|---|---|---|---|---|---|
| 200 V | 11 A | 13.8 A | 14 AWG | 30 A | 20 A |
| 208 V | 10.6 A | 13.2 A | 14 AWG | 30 A | 20 A |
| 230 V | 9.6 A | 12.0 A | 14 AWG | 25 A | 20 A |
| 460 V | 4.8 A | 6.0 A | 14 AWG | 15 A | 15 A |
| 575 V | 3.9 A | 4.9 A | 14 AWG | 15 A | 15 A |
3 HP single-phase motor
| Voltage | Full-load amps | Conductor ampacity (125%) | Min. copper wire, 75°C | Max. inverse-time breaker (250%) | Max. time-delay fuse (175%) |
|---|---|---|---|---|---|
| 115 V | 34 A | 42.5 A | 8 AWG | 90 A | 60 A |
| 200 V | 19.6 A | 24.5 A | 12 AWG | 50 A | 35 A |
| 208 V | 18.7 A | 23.4 A | 12 AWG | 50 A | 35 A |
| 230 V | 17 A | 21.2 A | 12 AWG | 45 A | 30 A |
3 HP DC motor
| Armature voltage | Full-load amps | Conductor ampacity (125%) |
|---|---|---|
| 120 V | 25 A | 31.2 A |
| 180 V | 16 A | 20.0 A |
| 240 V | 12.2 A | 15.2 A |
3 HP two-phase motor
| Voltage | Full-load amps |
|---|---|
| 230 V | 8.3 A |
| 460 V | 4.2 A |
| 575 V | 3.3 A |
3 HP is 2.24 kW of shaft output. Wire sizes above are the smallest copper conductor whose 75°C ampacity covers 125% of full-load current; 14 AWG is the practical minimum for power circuits. They do not include voltage drop — on long runs check the voltage drop calculator — or derating for hot locations or crowded conduits. Breaker and fuse values are maximums with the next-standard-size-up allowance applied; smaller devices are fine if the motor starts without tripping.
Motor wire & breaker size calculator
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Other horsepower ratings
- 1/6 HP
- 1/4 HP
- 1/3 HP
- 1/2 HP
- 3/4 HP
- 1 HP
- 1 1/2 HP
- 2 HP
- 3 HP
- 5 HP
- 7 1/2 HP
- 10 HP
- 15 HP
- 20 HP
- 25 HP
- 30 HP
- 40 HP
- 50 HP
- 60 HP
- 75 HP
- 100 HP
- 125 HP
- 150 HP
- 200 HP
- 250 HP
- 300 HP
- 350 HP
- 400 HP
- 450 HP
- 500 HP
Frequently asked questions
How many amps does a 3 HP motor draw?
A 3 HP motor draws 9.6 A at 230 V and 4.8 A at 460 V three-phase; 34 A at 115 V and 17 A at 230 V single-phase. These are the code table values used for circuit sizing; the actual nameplate current is usually a little lower.
What size wire and breaker for a 3 HP three-phase motor at 460 V?
Full-load current is 4.8 A, so conductors need at least 6.0 A of ampacity: 14 AWG copper at 75°C. The inverse-time breaker may be up to 15 A and a dual-element time-delay fuse up to 15 A.
What size wire for a 3 HP single-phase motor at 230 V?
17 A × 125% = 21.2 A, so 12 AWG copper is the minimum, with a breaker no larger than 45 A. At 115 V the current doubles to 34 A.
NECTables.com is an independent reference and is not affiliated with, endorsed by, or a substitute for the National Fire Protection Association (NFPA). NEC® and National Electrical Code® are registered trademarks of the NFPA. Values shown are commonly published engineering data and independent calculations based on the methods of NFPA 70; they are not a reproduction of the Code. Always confirm against the edition adopted in your jurisdiction, including local amendments, and consult a licensed electrician or engineer before doing electrical work.