1/3 HP Motor Amps — Full-Load Current, Wire & Breaker Size
Full-load current of a 1/3 horsepower motor at every standard voltage, with minimum conductor size and maximum breaker and fuse ratings worked out for each.
A 1/3 HP motor draws 7.2 A at 115 V and 3.6 A at 230 V single-phase.
1/3 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 | 7.2 A | 9.0 A | 14 AWG | 20 A | 15 A |
| 200 V | 4.1 A | 5.1 A | 14 AWG | 15 A | 15 A |
| 208 V | 4 A | 5.0 A | 14 AWG | 15 A | 15 A |
| 230 V | 3.6 A | 4.5 A | 14 AWG | 15 A | 15 A |
1/3 HP DC motor
| Armature voltage | Full-load amps | Conductor ampacity (125%) |
|---|---|---|
| 90 V | 5.2 A | 6.5 A |
| 120 V | 4.1 A | 5.1 A |
| 180 V | 2.6 A | 3.2 A |
| 240 V | 2 A | 2.5 A |
1/3 HP is 0.25 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 1/3 HP motor draw?
A 1/3 HP motor draws 7.2 A at 115 V and 3.6 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 for a 1/3 HP single-phase motor at 230 V?
3.6 A × 125% = 4.5 A, so 14 AWG copper is the minimum, with a breaker no larger than 15 A. At 115 V the current doubles to 7.2 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.