Motor Cable Size Calculator
Determine the optimal cable size for your motor applications based on current and material.
Motor Cable Size Calculator
Compliant with IEC and NEC Standards (Simplified)
Results:
Motor Current (A): 0.00
Recommended Copper Cable Size: N/A
Recommended Aluminum Cable Size: N/A
How to Use the Calculator
Input Motor & System Details
- Enter motor power (kW or HP) and select unit.
- Select system type (AC/DC) and phase (for AC).
- Input system voltage (V) and power factor (PF for AC).
- Enter the total cable length in meters.
Understand Cable Sizing Logic
- For motors less than 5kW and cable length less than 50m: Copper cables are sized at 3.5 Amps/mm², Aluminum at 2.5 Amps/mm².
- For motors 5kW or more: Copper cables are sized at 2.5 Amps/mm², Aluminum at 1.5 Amps/mm².
- The calculator provides a recommended minimum cable size based on these current densities.
Interpret Your Results
- View the calculated motor full-load current.
- See the recommended minimum cable cross-sectional area (mm²) for both Copper and Aluminum conductors.
- Always consult local electrical codes and a qualified electrician for final design and installation.
Motor Cable Sizing Fundamentals
Motor Full-Load Current (FLC)
The first critical step is calculating the motor's Full-Load Current (FLC). This current dictates the minimum current-carrying capacity required for the cable to safely operate without overheating.
- AC Single Phase: I = P / (V × PF)
- AC Three Phase: I = P / (√3 × V × PF)
- DC: I = P / V
Current Density
- Current density refers to the amount of current flowing through a unit cross-sectional area of a conductor (Amps/mm²).
- Higher current density requires larger cable sizes to prevent overheating and ensure safe operation.
- This calculator uses simplified current density values based on motor power and cable length for practical recommendations.
Key Factors for Cable Sizing:
1. Motor Full-Load Current (FLC)
2. Cable Length
3. Conductor Material (Copper/Aluminum)
4. Permissible Current Density (Amps/mm²)
Calculation Formulas (Simplified)
Motor Power Conversion (HP to kW):
P_kW = P_HP × 0.7457
AC Single Phase Current (A):
I = (P_kW × 1000) / (V × PF)
AC Three Phase Current (A):
I = (P_kW × 1000) / (√3 × V × PF)
DC Current (A):
I = (P_kW × 1000) / V
Required Cable Area (mm²):
Area = Current / Amps_per_mm²
Example Calculation
Consider a 3-Phase AC Motor:
Motor Power: 4 kW
Voltage: 400V
PF: 0.8
Cable Length: 30 meters
Current (I) = (4000) / (√3 × 400 × 0.8) ≈ 7.22 A
Since Power (4kW < 5kW) and Length (30m < 50m):
For Copper: Use 3.5 A/mm²
Min. Copper Area = 7.22 A / 3.5 A/mm² ≈ 2.06 mm²
Recommended Copper Cable Size: 2.5 mm²
For Aluminum: Use 2.5 A/mm²
Min. Aluminum Area = 7.22 A / 2.5 A/mm² ≈ 2.89 mm²
Recommended Aluminum Cable Size: 4 mm²
Results: Current = 7.22 A | Copper: 2.5 mm² | Aluminum: 4 mm²