Voltage Drop Calculator
Calculate voltage drop in DC/AC electrical circuits based on wire size, current, length, and material. This tool helps electricians and engineers ensure proper voltage levels in wiring installations.
Voltage Drop Results
| Voltage Drop (V): | 0 |
|---|---|
| Voltage Drop (%): | 0 |
| Voltage at Load (V): | 0 |
| Wire Resistance (Ω): | 0 |
| Power Loss (W): | 0 |
About the Voltage Drop Calculator
Our voltage drop calculator helps you determine the voltage loss in electrical circuits based on wire size, current, length, and material. Voltage drop is an important consideration in electrical installations to ensure proper operation of equipment and compliance with electrical codes.
How to Use the Calculator
- Select the system type (DC, AC Single Phase, or AC Three Phase)
- Choose the wire material (Copper or Aluminum)
- Select the wire size (AWG)
- Enter the circuit voltage (V)
- Enter the current (A)
- Enter the wire length (ft)
- For AC systems, enter the power factor (default is 0.85)
- Click "Calculate" to see the results
Voltage Drop Formulas
The calculator uses standard electrical formulas for voltage drop calculations:
DC Voltage Drop:
Voltage Drop (V) = 2 × I × R × L / 1000
Where:
I = Current (A)
R = Resistance (Ω/kft)
L = Length (ft)
AC Single Phase Voltage Drop:
Voltage Drop (V) = 2 × I × (R × cosθ + X × sinθ) × L / 1000
Where:
I = Current (A)
R = Resistance (Ω/kft)
X = Reactance (Ω/kft)
cosθ = Power Factor
L = Length (ft)
AC Three Phase Voltage Drop:
Voltage Drop (V) = √3 × I × (R × cosθ + X × sinθ) × L / 1000
Where:
I = Current (A)
R = Resistance (Ω/kft)
X = Reactance (Ω/kft)
cosθ = Power Factor
L = Length (ft)
Wire Resistance Values
The calculator uses standard resistance values for copper and aluminum wires at 75°C (167°F):
| AWG Size | Copper (Ω/kft) | Aluminum (Ω/kft) |
|---|---|---|
| 14 | 3.07 | 5.01 |
| 12 | 1.93 | 3.15 |
| 10 | 1.21 | 1.98 |
| 8 | 0.764 | 1.24 |
| 6 | 0.491 | 0.795 |
| 4 | 0.308 | 0.498 |
| 3 | 0.245 | 0.396 |
| 2 | 0.194 | 0.313 |
| 1 | 0.154 | 0.249 |
| 0 (1/0) | 0.122 | 0.197 |
| 00 (2/0) | 0.0967 | 0.156 |
| 000 (3/0) | 0.0766 | 0.124 |
| 0000 (4/0) | 0.0608 | 0.0983 |
Recommended Voltage Drop Limits
For branch circuits, the National Electrical Code (NEC) recommends a maximum voltage drop of 3% for optimal efficiency. For feeders and branch circuits combined, the recommended maximum is 5%.