AC Motor Calculations

⚡ AC Motor Calculations

Professional Motor Analysis & Design Tool

Motor ID HP Voltage (V) Phase Service Factor Length (ft) Ambient (°C) Max VD (%) Disconnect Mult. Fuse Mult. Breaker Mult. FLC (A) Conductor Size Ground Size Voltage Drop Breaker (A) Fuse (A) Disconnect (A) NEMA Size Overload (A) Conduit Size Actions
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📊 Ampacity Derating Factors (NEC 310.15(B)(3)(a))
Number of Current-Carrying Conductors Percent of Values in Tables Common Applications
1-3 100% Single motor, individual circuits
4-6 80% Two 3-phase motors in same conduit
7-9 70% Three 3-phase motors in same conduit
10-20 50% Multiple motors, control circuits
21-30 45% Large motor control centers
31-40 40% Industrial distribution panels
41 and above 35% High-density installations
Motor Full Load Current (NEC Table 430.250)
Enable HP 208V (A) 240V (A) 480V (A) 600V (A) Actions
Motor Branch-Circuit Protection (NEC Table 430.52)
Enable Type of Motor Non-Time Delay Fuse (%) Dual Element Fuse (%) Instantaneous Trip Breaker (%) Inverse Time Breaker (%) Motor FLA Rating Actions
Conductor Ampacity (NEC Table 310.15(B)(16))
Enable AWG Size THWN-2 (A) XHHW-2 (A) Resistance (Ω/1000ft) Actions
Equipment Grounding Conductor (NEC Table 250.122)
Enable Overcurrent Device (A) Copper EGC (AWG) Aluminum EGC (AWG) Actions
NEMA Starter Sizes
Enable NEMA Size Max HP @ 208V Max HP @ 480V Max Current (A) Actions
Standard Ampere Ratings (NEC Table 240.6(A))
Enable Standard Rating (A) Device Type Common Applications Actions
Conduit Fill (NEC Chapter 9, Table 4 & Annex C)
Enable Conduit Size 40% Fill (in²) Max #12 THWN Max #10 THWN Max #8 THWN Actions