Full Load Amps (FLA) is the current a motor draws at full rated horsepower and voltage. NEC Tables 430.248 (single-phase) and 430.250 (three-phase) list FLA values used for branch circuit sizing — these are used for conductors, OCPD, and starter sizing, even if the motor nameplate shows a different number.

Do I use the nameplate FLA or the NEC table value?

For sizing conductors and OCPD, use NEC Table 430.248/430.250 values. The nameplate FLA is used for overload relay sizing (NEC 430.52 says overloads are set to 115-125% of nameplate FLA, not table FLA).

What size conductor for a motor branch circuit?

NEC 430.22 requires branch circuit conductors at 125% of motor FLA (from Table 430.248 or 430.250). For a 5 HP, 460V three-phase motor (FLA = 7.6A): 7.6 × 1.25 = 9.5A minimum. Select the next conductor that meets or exceeds 9.5A at your termination temp rating.

What size OCPD for a motor?

Per NEC 430.52, OCPD sizing depends on type: Inverse time breaker = 250% of FLA; Time-delay fuse = 175% of FLA; Non-time-delay fuse = 300% of FLA. Always round up to the next standard size, with a 400% absolute maximum for inverse time breakers.

Why does voltage matter for FLA?

For the same horsepower, higher voltage means lower current (P = V × I × √3 for 3-phase). A 10 HP motor at 460V draws about 14A while the same motor at 230V draws about 28A. Always match the FLA table to the system voltage.

Motor FLA Calculator — NEC 430.248 / 430.250

Full load ampere lookup per NEC Tables 430.248 and 430.250. Select horsepower, phase, and voltage to get FLA — plus branch circuit conductor and OCPD sizing.

Phase

Voltage

Motor horsepower

OCPD type

Full Load Amps (NEC Table)

—

Min. conductor (125%)

—

NEC 430.22

Max OCPD size

—

NEC 430.52

Overload relay (125%)

—

Use nameplate FLA × 1.25

NEC Table 430.250 — Three-Phase Motor FLA Reference

HP	208V	230V	460V	575V
1/2	2.4	2.0	1.0	0.8
3/4	3.5	2.8	1.4	1.1
1	4.6	3.6	1.8	1.4
1-1/2	6.6	5.2	2.6	2.1
2	7.5	6.8	3.4	2.7
3	10.6	9.6	4.8	3.9
5	16.7	15.2	7.6	6.1
7-1/2	24.2	22.0	11.0	9.0
10	30.8	28.0	14.0	11.0
15	46.2	42.0	21.0	17.0
20	59.4	54.0	27.0	22.0
25	74.8	68.0	34.0	27.0
30	88.0	80.0	40.0	32.0
40	114.0	104.0	52.0	41.0
50	143.0	130.0	65.0	52.0
60	169.0	154.0	77.0	62.0
75	211.0	192.0	96.0	77.0
100	273.0	248.0	124.0	99.0
125	343.0	312.0	156.0	125.0
150	396.0	360.0	180.0	144.0
200	528.0	480.0	240.0	192.0

NEC Table 430.248 — Single-Phase Motor FLA Reference

HP	115V	230V
1/6	4.4	2.2
1/4	5.8	2.9
1/3	7.2	3.6
1/2	9.8	4.9
3/4	13.8	6.9
1	16.0	8.0
1-1/2	20.0	10.0
2	24.0	12.0
3	34.0	17.0
5	56.0	28.0
7-1/2	80.0	40.0
10	100.0	50.0

How motor branch circuit sizing works

Motor branch circuits live under NEC Article 430, which has its own rules that differ from standard branch circuits. There are three separate sizing decisions: the conductor, the overcurrent protection device (OCPD), and the overload relay.

Branch circuit conductors — NEC 430.22

Conductors must be sized at 125% of the motor FLA from Table 430.248 or 430.250 — not the nameplate. This means a motor with 28A FLA requires conductors rated for at least 35A continuous (28 × 1.25). The 125% is already built into the conductor ampacity column you pick from NEC Table 310.16.

Min conductor current = FLA (table) × 1.25 Example: 10 HP, 460V, 3Ø → 14A × 1.25 = 17.5A → use #12 AWG copper (20A @60°C)

Overcurrent protection — NEC 430.52

Motor OCPD is sized larger than the conductor to allow the motor to start without tripping. The maximum sizes by device type:

Inverse time circuit breaker: 250% of FLA
Time-delay (dual-element) fuse: 175% of FLA
Non-time-delay fuse: 300% of FLA
Absolute maximum (breaker): 400% — if the next standard size above 250% exceeds 400%, you must use 400% or less

Always round up to the next standard fuse or breaker size. Standard breaker sizes: 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250A.

Overload relay — NEC 430.32

The overload protects the motor winding from sustained overload, not from short circuits. Set it to nameplate FLA × 1.25 (or × 1.15 if the motor has a 1.0 service factor). The overload relay is what actually trips if the motor is overloaded — the OCPD handles short circuits and grounds.

Frequently asked questions

Table FLA vs. nameplate FLA — which do I use?

Table values for conductors and OCPD (NEC 430.22 and 430.52). Nameplate values for overload relays (NEC 430.32). The table values tend to be higher, which is why motor branch circuits look oversized — that's by design.

What if I can't find my HP in the table?

Interpolate — or size up to the next HP. NEC 430.6 says to use the table value for the HP rating that most closely applies. When in doubt, go up.

Do I need a disconnect at the motor?

Yes. NEC 430.102 requires a disconnecting means within sight of the motor and controller. "Within sight" means visible and within 50 feet. A lockable safety switch or motor-circuit switch is typical.

Can the motor branch circuit also serve other loads?

Generally no. NEC 430.53 permits multiple motors on one circuit under specific conditions (all under 1 HP, or all small motors with a single OCPD), but for most installations each motor gets its own branch circuit.

What's a service factor?

Service factor (SF) is a multiplier on the motor nameplate indicating how much overload the motor can sustain. SF 1.15 means the motor can operate at 115% of rated load continuously. Used only for overload relay sizing — conductors and OCPD always size to 100% FLA.