Motor Full Load Amps — Table, Not Nameplate
A motor circuit uses two different current figures, and mixing them up is the single most common motor-wiring error. NEC 430.6(A)(1) requires conductors and the branch-circuit protective device to be sized from the table full-load current. Only the overload device uses the nameplate. This tool gives you both.
Look up the full-load current
Used only for the overload device.
Table full-load current
Conductors and the breaker use this
430.22 ampacity
17.50 A
Minimum conductor
14 AWG
430.32 overload, from the nameplate
16.25 A
See the breakdown
The table value is 7.7% above this nameplate — normal, because Table 430.250 is deliberately conservative.
The method, explained in plain English
Why the table is conservative
The wiring has to suit any motor of that horsepower installed over the life of the circuit, not just today's. A replacement motor never outgrows conductors sized from the table.
240.4(D) does not apply
240.4(G) routes motor circuits to 430.52, so the small-conductor caps that limit 14 AWG to 15 A elsewhere are off. 12 AWG is still the sensible practical minimum.
Compressors are Article 440
Hermetic refrigerant motor-compressors use the nameplate rated-load current, or the MCA and MOCP marked on the equipment — not these tables.
Use the nearest listed voltage
A 480 V system takes the 460 V column and a 600 V system the 575 V column. The table voltage is the motor's rating, not the system's nominal.
Worked examples
The same 10 HP motor, and the three numbers a complete circuit needs.
10 HP, three-phase, 460 V
The defaults above, with a 13.0 A nameplate.
conductors: 14 × 1.25 = 17.5 A → 14 AWG Cu (20 A at 75 °C)
overload: 13.0 × 125% = 16.25 A
Result: the table reads 7.7% above the nameplate. Use 14 A for the wiring and 13.0 A for the overload — never the other way round.
The same motor on 230 V
Halve the voltage and the current doubles.
conductors: 28 × 1.25 = 35.0 A → 8 AWG Cu
Result: two conductor sizes larger for identical mechanical work. This is why industrial motor loads run at 460 V wherever it is available.
50 HP, three-phase, 460 V
Where the numbers get expensive.
conductors: 65 × 1.25 = 81.25 A → 4 AWG Cu
Result: note that the FLC is not proportional to horsepower — efficiency and power factor both improve with size, so a 50 HP motor draws less than five times a 10 HP motor.
NEC Table 430.250 — three-phase motors
Full-load current in amperes for squirrel-cage and wound-rotor induction motors. These are the values conductors and the branch-circuit protective device are sized from.
| HP | 200 V | 208 V | 230 V | 460 V | 575 V |
|---|---|---|---|---|---|
| 1 | 4.8 | 4.6 | 4.2 | 2.1 | 1.7 |
| 1-1/2 | 6.9 | 6.6 | 6 | 3 | 2.4 |
| 2 | 7.8 | 7.5 | 6.8 | 3.4 | 2.7 |
| 3 | 11 | 10.6 | 9.6 | 4.8 | 3.9 |
| 5 | 17.5 | 16.7 | 15.2 | 7.6 | 6.1 |
| 7-1/2 | 25.3 | 24.2 | 22 | 11 | 9 |
| 10 | 32.2 | 30.8 | 28 | 14 | 11 |
| 15 | 48.3 | 46.2 | 42 | 21 | 17 |
| 20 | 62.1 | 59.4 | 54 | 27 | 22 |
| 25 | 78.2 | 74.8 | 68 | 34 | 27 |
| 30 | 92 | 88 | 80 | 40 | 32 |
| 40 | 120 | 114 | 104 | 52 | 41 |
| 50 | 150 | 143 | 130 | 65 | 52 |
| 60 | 177 | 169 | 154 | 77 | 62 |
| 75 | 221 | 211 | 192 | 96 | 77 |
| 100 | 285 | 273 | 248 | 124 | 99 |
NEC Table 430.248 — single-phase motors
| HP | 115 V | 200 V | 208 V | 230 V | 430.22 at 230 V |
|---|---|---|---|---|---|
| 1/6 | 4.4 | 2.5 | 2.4 | 2.2 | 2.75 A |
| 1/4 | 5.8 | 3.3 | 3.2 | 2.9 | 3.63 A |
| 1/3 | 7.2 | 4.1 | 4 | 3.6 | 4.50 A |
| 1/2 | 9.8 | 5.6 | 5.4 | 4.9 | 6.13 A |
| 3/4 | 13.8 | 7.9 | 7.6 | 6.9 | 8.63 A |
| 1 | 16 | 9.2 | 8.8 | 8 | 10.00 A |
| 1-1/2 | 20 | 11.5 | 11 | 10 | 12.50 A |
| 2 | 24 | 13.8 | 13.2 | 12 | 15.00 A |
| 3 | 34 | 19.6 | 18.7 | 17 | 21.25 A |
| 5 | 56 | 32.2 | 30.8 | 28 | 35.00 A |
| 7-1/2 | 80 | 46 | 44 | 40 | 50.00 A |
| 10 | 100 | 57.5 | 55 | 50 | 62.50 A |
Sources & standards: NEC (NFPA 70) 2023 — 430.6(A)(1) (table values govern conductors and the branch-circuit device), 430.22 (conductors at 125%), 430.32(A)(1) and 430.32(C) (overload from the nameplate), Table 430.248, Table 430.250, 240.4(G), Table 310.16, and Article 440 for hermetic refrigerant motor-compressors. Local amendments override the model code, and the AHJ has final say.
Frequently asked questions
Common questions about motor full-load amperes.
Why does the NEC make me use a table instead of the motor nameplate?
Because NEC 430.6(A)(1) says so, and there is a good reason. Conductors and the branch-circuit short-circuit device have to work for any motor that might be installed on that circuit over its life, not just the one on the shelf today. The table values are deliberately conservative so a replacement motor of the same horsepower never outgrows the wiring. The nameplate is used for the overload device, which is matched to the actual machine.
Which number do I use for the overload device?
The nameplate full-load amperes, per 430.32. That is the one place in Article 430 where the nameplate governs. A motor with a marked service factor of 1.15 or greater, or a marked temperature rise of 40 °C or less, gets 125% of nameplate; everything else gets 115%. 430.32(C) allows an increase to 140% or 130% if the motor will not start on the lower setting.
What if the nameplate reads higher than the table?
It happens on some older or special-purpose motors. It changes nothing about the method: conductors and the branch-circuit device still come from the table under 430.6(A)(1), and the overload still comes from the nameplate. If the nameplate is dramatically higher, check whether the motor is actually the horsepower you think it is, or whether it is a multispeed, torque, or hermetic-refrigerant motor — those have their own rules in 430.6 and 440.
Do these tables cover air conditioners and refrigeration compressors?
No. A hermetic refrigerant motor-compressor is covered by Article 440, and you use the nameplate rated-load current or the branch-circuit selection current where one is marked — not Table 430.248 or 430.250. In practice you follow the MCA (minimum circuit ampacity) and MOCP (maximum overcurrent protection) marked on the equipment nameplate.
How do I convert horsepower to amps if my voltage is not listed?
The tables only list 115, 200, 208 and 230 V single-phase, and 200, 208, 230, 460 and 575 V three-phase, because those are the nominal system voltages the code recognises for this purpose. For an unlisted voltage you use the nearest listed nominal voltage — a 480 V system uses the 460 V column, and a 600 V system uses the 575 V column. That is the standard convention: the table voltage is the motor's rated voltage, not the system's.
Why is 14 AWG allowed on a 10 HP motor?
Because 240.4(G) routes motor circuits to 430.52, which means the 240.4(D) small-conductor caps that limit 14 AWG to 15 A elsewhere do not apply. A 10 HP 460 V motor draws 14 A from the table, so 430.22 needs 17.5 A of ampacity and 14 AWG copper at 75 °C provides 20 A. It is compliant — but 12 AWG is the normal practical minimum, and many specifications and jurisdictions require it.
What is service factor and where do I find it?
Service factor is a multiplier printed on the nameplate as SF — how much above rated horsepower the motor can run continuously without damage. A 1.15 service factor means it tolerates 15% overload. It matters here only because 430.32(A)(1) gives motors marked 1.15 or greater the more generous 125% overload setting rather than 115%.
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