How Many Amps Does a 0.75 HP three-phase Motor Draw at 240V?

Q: What is 0.75 HP in watts?

0.75 HP equals 559.5 watts of mechanical output (1 HP = 746 W). The electrical input at the terminals is higher because no motor is 100% efficient: at 85% efficiency the input is about 658.24 W.

A 0.75 HP three-phase motor at 240V draws approximately 1.86 amps per line during normal operation (85% efficiency, PF 0.85). Startup current can be 5-7 times the NEC Table 430.250 FLC (16-22.4 A) for a few seconds, which affects breaker and wire sizing.

Common applications for 0.75 HP motors: pool pumps, well pumps, compressor fans, table saws.

0.75 HP three-phase motor at 240V

1.86 Amps per line running

Calculated running current at the motor terminals at the assumed 85% efficiency and PF 0.85, per line on a balanced three-phase circuit. This is a conversion from the nameplate horsepower using those assumptions, not a measured value; a real meter reading depends on the motor's actual nameplate efficiency, loading, temperature, and motor design.

NEC Table 430.250 FLC (code sizing base)3.2 A

Conductor min ampacity (NEC 430.22, 125% of FLC)4 A

Electrical input (HP × 746 ÷ efficiency)658.24 W

Try: 3/4HP at 240V (3Φ) 1/2HP at 240V (3Φ) 1HP at 240V (3Φ) 1/3HP at 240V (3Φ)

Volts

Motor Type

Running Amps (per line)

1.86

NEC Table 430.250 FLC (code sizing)

3.2

Use the running amps for metering and energy calculations. For branch-circuit sizing, AC motors use the NEC Table 430.248 / 430.250 full-load current under NEC 430.6(A)(1); DC motors use the motor nameplate full-load current under NEC 430.6(A)(3), with Table 430.247 as the reference. Three-phase current is shown per line on a balanced circuit.

Formula (three-phase)

I_(A) = (HP × 746) ÷ (√3 × V_L-L × Eff × PF)

(0.75 × 746) ÷ (√3 × 240 × 0.85 × 0.85) = 559.5 ÷ 300.34 = 1.86 A per line

Convert HP to watts: 0.75 × 746 = 559.5W
Denominator: √3 × 240 × 0.85 × 0.85 = 1.73 × 240 × 0.85 × 0.85 = 300.34
Result: 559.5 ÷ 300.34 = 1.86 amps per line

Three-phase current is per line on a balanced circuit. Voltage is line-to-line; the √3 factor comes from the three-phase vector geometry, not a round-trip doubling.

NEC Reference Values

This section lists the Code reference numbers a motor branch circuit is sized from. Final conductor, breaker, disconnect, and overload selection is an install decision a licensed electrician makes against the motor nameplate, the actual install conditions, and the applicable NEC articles, not a decision a conversion page can make for you.

NEC Sizing Base: NEC Table 430.250 FLC

Per NEC 430.6(A)(1), motor branch-circuit conductors, switches, and overcurrent protection are sized from the values in Table 430.248 (single-phase) or Table 430.250 (three-phase), not from the motor nameplate and not from a calculated full-load amps. For a 0.75 HP three-phase motor at 240V, the table value is 3.2 A (the 230V column covers 220-240V under 430.6(A)(1)).

The 1.86 A shown in the hero is the calculated running current at 85% efficiency and PF 0.85, per line on a balanced three-phase circuit. This is a conversion from the nameplate horsepower under those assumptions, not a measured value; a real meter reading depends on the motor's actual efficiency, loading, temperature, and design. Use this figure for energy and metering estimates, and use 3.2 A as the reference FLC when an electrician walks through NEC 430 against the nameplate.

NEC 430.22 Conductor Rule (reference formula)

NEC 430.22 requires motor branch-circuit conductor ampacity of at least 125% of the Code sizing FLC. As a reference calculation against the NEC Table 430.250 value: 3.2 × 1.25 = 4 A. The selected conductor is taken from NEC Table 310.16 at the applicable termination temperature column, with ambient, bundling, and cable-type adjustments applied by the installer. Motor branch-circuit conductors are exempt from the 240.4(D) small-conductor rule via 240.4(G).

NEC 430.52 Overcurrent Protection (code caps)

NEC Table 430.52(C)(1) gives the maximum rating for motor short-circuit and ground-fault protection as a percentage of the Code sizing FLC. The percentage depends on the device type:

Device Type	Maximum % of Table FLC (430.52(C)(1))
Non-time-delay fuse	300%
Dual-element (time-delay) fuse	175%
Inverse-time circuit breaker	250%
Instantaneous-trip circuit breaker	800%

These percentages are maximum caps, not install picks. A real circuit applies the percentage against the Code sizing FLC for the specific device type, rounds up to a standard size per 430.52(C)(1)(a), and is verified against the motor nameplate and the install conditions by the installer. The elevated percentages exist so short-circuit protection does not nuisance-trip on locked-rotor startup inrush.

Locked Rotor (Startup) Current

During the first 2-5 seconds of startup, a squirrel-cage induction motor typically draws 5 to 7 times the NEC Table 430.250 FLC of 3.2 A (roughly 16 to 22.4 A). This is why the 430.52(C)(1) percentages above are so much higher than running current: the short-circuit/ground-fault protective device has to ride through locked-rotor inrush without tripping. Actual LRA is set by the motor's NEMA code letter on the nameplate and should be checked there for a real install.

Current	Amps	Duration
Calculated running current (meter)	1.86 A per line	Continuous at full load
NEC Table 430.250 FLC (Code reference)	3.2 A	Sizing base, not metered
Locked rotor (typical, 5-7×)	16-22.4 A	2-5 seconds

Operating Cost

Motor mechanical output is 559.5 W (0.75 HP × 746). Electrical input at the terminals is higher because no motor is 100% efficient: 559.5 ÷ 0.85 = 658.24 W. At $0.17/kWh, running cost is $0.11/hour or $26.86/month at 8 hours/day. Full breakdown at 658.24 W.

Amps by Motor Efficiency (three-phase)

Motor efficiency directly affects amp draw. A more efficient motor draws less current for the same HP output. Values below are the calculated three-phase running current at 240V per line and PF 0.85:

Efficiency	Amps at 240V (per line)	Watts Consumed	Waste Heat
75%	2.11 A	746 W	186.5 W
80%	1.98 A	699.38 W	139.88 W
85%	1.86 A	658.24 W	98.74 W
90%	1.76 A	621.67 W	62.17 W
95%	1.67 A	588.95 W	29.45 W

Other HP Values at 240V (three-phase)

Running current is the calculated three-phase draw per line at 85% efficiency and 0.85 PF (a conversion from HP under those assumptions, not a measured value). NEC Table FLC is the value from NEC Table 430.250 used for branch-circuit conductor and OCP sizing under NEC 430.6(A)(1). LRA is estimated at 5-7× the NEC table FLC; rows outside the table show n/a because there is no code-authoritative LRA basis for that HP/voltage/phase combination. Row links open each result page in three-phase mode.

HP	Running Amps (calculated)	NEC Table 430.250 FLC	LRA Estimate (5-7× FLC)
1/8 HP	0.3105 A	off-table	n/a
1/6 HP	0.4141 A	off-table	n/a
1/4 HP	0.621 A	off-table	n/a
1/3 HP	0.8279 A	off-table	n/a
1/2 HP	1.24 A	2.2 A	11-15.4 A
3/4 HP	1.86 A	3.2 A	16-22.4 A
1 HP	2.48 A	4.2 A	21-29.4 A
1.5 HP	3.73 A	6 A	30-42 A
2 HP	4.97 A	6.8 A	34-47.6 A
3 HP	7.45 A	9.6 A	48-67.2 A
5 HP	12.42 A	15.2 A	76-106.4 A
7.5 HP	18.63 A	22 A	110-154 A
10 HP	24.84 A	28 A	140-196 A
15 HP	37.26 A	42 A	210-294 A
20 HP	49.68 A	54 A	270-378 A
25 HP	62.1 A	68 A	340-476 A
30 HP	74.52 A	80 A	400-560 A
40 HP	99.35 A	104 A	520-728 A
50 HP	124.19 A	130 A	650-910 A
75 HP	186.29 A	192 A	960-1,344 A

Same HP, Other Voltages (three-phase)

speed 0.75 HP at 120V = 3.73A per line speed 0.75 HP at 208V = 2.15A per line speed 0.75 HP at 220V = 2.03A per line speed 0.75 HP at 230V = 1.94A per line speed 0.75 HP at 400V = 1.12A per line speed 0.75 HP at 480V = 0.9315A per line

Related Calculations

bolt 658W electrical input to amps at 240V payments 658W running cost cable Wire size for 4A at 240V (3Φ) (NEC 430.22 minimum: 125% of 3.2A NEC Table 430.250 FLC)

Frequently Asked Questions

How many amps does a 0.75 HP three-phase motor draw at 240V?expand_more

At the terminals, a 0.75 HP three-phase motor at 240V draws about 1.86 amps per line at 85% efficiency and 0.85 power factor. For NEC branch-circuit sizing use the NEC Table 430.250 full-load current instead: 3.2 A.

What is 0.75 HP in watts?expand_more

0.75 HP equals 559.5 watts of mechanical output (1 HP = 746 W). The electrical input at the terminals is higher because no motor is 100% efficient: at 85% efficiency the input is about 658.24 W.

What does NEC 430.52(C)(1) say about OCP for a 0.75 HP three-phase motor?expand_more

NEC Table 430.52(C)(1) gives the maximum OCP rating as a percentage of the NEC Table 430.250 FLC. The ceilings by device type are 300% for non-time-delay fuses, 175% for dual-element (time-delay) fuses, 250% for inverse-time circuit breakers, and 800% for instantaneous-trip breakers. These percentages are ceilings, not starting points, and 250% is not a blanket motor rule. The actual max for a specific install comes from picking the device type, applying the matching percentage to the 3.2 A NEC Table 430.250 FLC, rounding up to a standard size per 430.52(C)(1)(a), and verifying against the motor startup profile.

What is locked rotor amps for a 0.75 HP three-phase motor?expand_more

Locked-rotor (startup) current typically runs 5-7 times the NEC Table 430.250 FLC for a squirrel-cage induction motor: 16-22.4 A for 2-5 seconds. The exact value depends on the NEMA code letter stamped on the motor nameplate.

Does motor efficiency affect amp draw?expand_more

Yes. A 0.75 HP three-phase motor at 90% efficiency draws 1.76 A at the terminals versus 2.11 A at 75% efficiency. Higher efficiency means lower running amps and lower electrical input wattage for the same mechanical output.

This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.