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Electrical Motors - Full Load Amps

Full load amps for single and 3-phase 460 volts, 230 volts and 115 volts electric motors.

As a "rules of thumb" amps horsepower rating can be estimated to

  • 115 volts motor - single-phase : 14 amps/hp
  • 230 volts motor - single-phase : 7 amps/hp
  • 230 volts motor - 3-phase : 2.5 amps/hp
  • 460 volts motor - 3-phase : 1.25 amps/hp

Always check nameplate information before designing protective devices, wiring and switch gear. 

Electric motor

Single-Phase Motors - HP and Full-Load Currents

A motor of a given rated horsepower is expected to deliver that quantity of mechanical power at the motor shaft. Be aware that the motor efficiency is not calculated in to the values for kW and amps below. Motor efficiency must be considered to avoid undersized power supply.

Single-Phase Electrical Motors - Full Load Amps
PowerFull Load Current (amp)
(hp)(kW)115 V208 V230 V
1/6 0.13 4.4 2.4 2.2
1/4 0.19 5.8 3.2 2.9
1/3 0.25 7.2 4.0 3.6
1/2 0.38 9.8 5.4 4.9
3/4 0.56 13.8 7.6 6.9
1 0.75 16 8.8 8
1 1/2 1.1 20 11 10
2 1.5 24 13.2 12
3 2.3 34 18.7 17
5 3.8 56 30.8 28

Note that most electric motors are designed to run at 50% to 100% of rated load and that maximum efficiency usually is near 75% of rated load. For a 1 horsepower (hp) motor the load should typically be in the range 1/2 to 1 hp with maximum efficiency at 3/4 hp. 

Typical load ranges:

  • acceptable for a short-period: 20 - 120%
  • acceptable for operating: 50 - 100%
  • optimum efficiency: 60 - 80%  

A motor with a service factor can occasional be overloaded. Overloading will over time reduce motor efficiency.

Three-Phase Motors - HP and Full-Load Currents

Three-Phase Electrical Motors - Full Load Amps
PowerFull-Load Current (amp)
Induction Type
Squirrel-Cage and Wound Motor
Synchronous Type
Unity Power Factor
(hp)(kW)115 V230 V460 V575 V2300 V230 V460 V575 V2300 V
1/2 0.38 4 2 1 0.8
3/4 0.56 5.6 2.8 1.4 1.1
1 0.75 7.2 3.6 1.8 1.4
1 1/2 1.1 10.4 5.2 2.6 2.1
2 1.5 13.6 6.8 3.4 2.7
3 2.3 9.6 4.8 3.9
5 3.8 15.2 7.6 6.1
7 1/2 5.6 22 11 9
10 7.5 28 14 11
15 11 42 21 17
20 15 54 27 22
25 19 68 34 27 53 26 21
30 23 80 40 32 63 32 26
40 30 104 52 41 83 41 33
50 38 130 65 52 104 52 42
60 45 154 77 62 16 123 61 49 12
75 56 192 96 77 20 155 78 62 15
100 75 248 124 99 26 202 101 81 20
  • 1 hp (English horse power) = 745.7 W = 0.746 kW = 550 ft lb/s = 2,545 Btu/h = 33.000 ft lb/m = 1.0139 metric horse power ~= 1.0 KVA

Direct Current Motors - Power and Full Load Currents

DC Electrical Motors - Full Load Amps
PowerDirect Current (A)
(hp)(kW)230 V440 V
1/4 0.19 0.81 0.42
1/3 0.25 1.1 0.56
1/2 0.37 1.6 0.85
3/4 0.56 2.4 1.3
1 0.75 3.2 1.7
1 1/2 1.1 4.9 2.5
2 1.5 6.5 3.4
3 2.2 9.7 5.1
5 3.7 16 8.5
7 1/2 5.6 24 13
10 7.5 32 17
15 11 49 25
20 15 65 34
30 22 97 51
50 37 162 85
75 56 243 127
100 75 324 170
  • for 115V - the amps is twice the amps for 230V

Related Topics

  • Electrical

    Electrical engineering with units, amps and electrical wiring. Wire gauges, electrical formulas, motors and more.

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