Utilize our Copper vs Aluminum Wire Gauge Sizing Calculator to quickly determine the ideal wire size for your electrical installations. Ensure minimal voltage drop and meet NEC ampacity guidelines based on your load, voltage, distance, and conductor material. Make informed decisions for safe and efficient wiring projects!
Formula:
The primary calculation in determining wire gauge for voltage drop involves a rearrangement of the voltage drop formula. This calculator first determines the minimum required circular mil area (CM) to stay within your specified voltage drop limits, then suggests the appropriate AWG/kcmil size. Ampacity is also considered for safety.
Voltage Drop Formula (Single Phase):
Vdrop = (2 × K × I × L) / CM
Voltage Drop Formula (Three Phase):
Vdrop = (√3 × K × I × L) / CM
To find the required Circular Mils (CM):
Required CM (Single Phase): CM = (2 × K × I × L) / Vdrop
Required CM (Three Phase): CM = (√3 × K × I × L) / Vdrop
Where:
- Vdrop = Maximum allowed Voltage Drop (Volts)
- K = Resistivity of the conductor (Ohms-Circular Mil/foot). Copper ≈ 12.9; Aluminum ≈ 21.2 (at 75°C)
- I = Load Current (Amps)
- L = One-way length of the circuit (Feet)
- CM = Cross-sectional Area of the conductor (Circular Mils)
- √3 ≈ 1.732 (for three-phase calculations)