⚡ Quick Presets — Common NEC Services EV L2 32A EV L2 40A EV L2 48A 50A Subpanel 100A Subpanel 200A Service 30A Dryer 40A Range 10 HP Motor 25 HP Motor ⚡ Resistive / General Load ⚙ Motor Branch Circuit (NEC 430) Load Amps (A) Load Power (kW, optional) Leave blank if entering amps directly. System Voltage (V) 120 V 208 V 220 V 240 V 277 V 347 V 380 V 480 V 600 V Phase 1Φ Single-Phase 3Φ Three-Phase Power Factor (cosφ) Resistive load = 1.0. Motor load = 0.85 typical. Continuous load (NEC 210.20(A) — 125% rule) Required for EV chargers, solar PV inverters, and any load expected to run > 3 hours. Motor Power (HP) NEMA/IEC Design Letter B — Standard (most common, 250% FLA) A — High torque, normal locked-rotor (250% FLA) C — High starting torque (150% FLA) E — IEC premium efficiency (150% FLA) D — Very high locked-rotor (150% FLA) Motor Voltage (V) 115 V 208 V 220 V 230 V 240 V 380 V 460 V 480 V 575 V 600 V Motor Phase 1Φ Single-Phase 3Φ Three-Phase FLA is looked up from NEC Table 430.250 (3Φ) or 430.6 (1Φ). Per NEC 430.52, inverse-time breaker = 250% of FLA for Design A/B; 150% for Design C/E/D. Recommended OCPD — amperes Running Amps — A Design Amps — A Calculation Details Run current — NEC 210.20(A) 125% rule — NEC 240.4(B) round-up — NEC 240.6(A) standard rating — Enter load values to see the formula. 📊 NEC 240.6(A) Standard OCPD Sizes (click to expand) Standard OCPD (A)Common Use 15General lighting, 14 AWG 20General receptacles, 12 AWG 25Select appliances 30Dryer (small), water heater, 10 AWG 35Limited use 40Range (small), 8 AWG 45Limited use 50Subpanel feeders, 6 AWG, hot tub 60EV L2 48A continuous, 6 AWG 70Limited use 80Subpanel feeders 90Subpanel feeders 100Subpanel feeders, 3 AWG 110Service entrance 125Service entrance, 1/0 AWG 150Service entrance 175Service entrance, 2/0 AWG 200Residential service, 3/0 AWG 225Service entrance 250Commercial service 300Commercial service 350Commercial service 400Commercial service 450Industrial service 500Industrial service 600Industrial service 700Industrial service 800Industrial service Source: NFPA 70 — National Electrical Code 2023, Section 240.6(A). 📊 NEC Table 430.250 — 3-Phase Motor FLA Reference (click to expand) HP208 V230 V460 V 0.52.42.21.1 0.753.53.21.6 14.64.22.1 1.56.66.03.0 27.56.83.4 310.69.64.8 516.715.27.6 7.524.222.011.0 1030.828.014.0 1546.242.021.0 2059.454.027.0 2574.868.034.0 3088.080.040.0 40114.0104.052.0 50143.0130.065.0 60169.0154.077.0 75211.0192.096.0 100273.0248.0124.0 Source: NFPA 70 — National Electrical Code 2023, Table 430.250 (3-phase induction motors, full-load amperes). ⚠️ Reference only. OCPD sizing is NEC-aware but final conductor and breaker sizing must be verified by a licensed electrician and approved by your local Authority Having Jurisdiction (AHJ). Always follow the latest edition of NFPA 70 — National Electrical Code. TL;DR — 本计算器输出内容。 输入负载电流、kW,或马达 HP(NEC 430 分支电路),工具按以下规则返回推荐的标准 OCPD(过电流保护装置 / 断路器):
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