7 1/2 HP Motor Amps — Full-Load Current, Wire & Breaker Size
Full-load current of a 7 1/2 horsepower motor at every standard voltage, with minimum conductor size and maximum breaker and fuse ratings worked out for each.
A 7 1/2 HP motor draws 22 A at 230 V and 11 A at 460 V three-phase; 80 A at 115 V and 40 A at 230 V single-phase.
7 1/2 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 | 25.3 A | 31.6 A | 10 AWG | 70 A | 45 A |
| 208 V | 24.2 A | 30.2 A | 10 AWG | 70 A | 45 A |
| 230 V | 22 A | 27.5 A | 10 AWG | 60 A | 40 A |
| 460 V | 11 A | 13.8 A | 14 AWG | 30 A | 20 A |
| 575 V | 9 A | 11.2 A | 14 AWG | 25 A | 20 A |
7 1/2 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 | 80 A | 100.0 A | 3 AWG | 200 A | 150 A |
| 200 V | 46 A | 57.5 A | 6 AWG | 125 A | 90 A |
| 208 V | 44 A | 55.0 A | 6 AWG | 110 A | 80 A |
| 230 V | 40 A | 50.0 A | 8 AWG | 100 A | 70 A |
7 1/2 HP DC motor
| Armature voltage | Full-load amps | Conductor ampacity (125%) |
|---|---|---|
| 120 V | 58 A | 72.5 A |
| 240 V | 29 A | 36.2 A |
| 500 V | 13.6 A | 17.0 A |
| 550 V | 12.2 A | 15.2 A |
7 1/2 HP two-phase motor
| Voltage | Full-load amps |
|---|---|
| 230 V | 19 A |
| 460 V | 9 A |
| 575 V | 8 A |
7 1/2 HP is 5.59 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
Loading calculator…
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 7 1/2 HP motor draw?
A 7 1/2 HP motor draws 22 A at 230 V and 11 A at 460 V three-phase; 80 A at 115 V and 40 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 7 1/2 HP three-phase motor at 460 V?
Full-load current is 11 A, so conductors need at least 13.8 A of ampacity: 14 AWG copper at 75°C. The inverse-time breaker may be up to 30 A and a dual-element time-delay fuse up to 20 A.
What size wire for a 7 1/2 HP single-phase motor at 230 V?
40 A × 125% = 50.0 A, so 8 AWG copper is the minimum, with a breaker no larger than 100 A. At 115 V the current doubles to 80 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.