Voltage Drop Calculator
Calculate voltage drop in electrical wires and cables for power transmission systems
Calculate Voltage Drop
Distance from source to load
Voltage at the source
Current flowing through the wire
Parallel conductors reduce resistance
Voltage Drop Results
Electrical Properties
Voltage Drop Analysis
Very low voltage drop, excellent performance
Formula: V = 2 × I × L × ρ / (A × n)
Where: V = voltage drop, I = current, L = length, ρ = resistivity, A = cross-sectional area, n = number of conductors
Recommendations
Example Calculation
Household Wiring Example
Wire: 12 AWG Copper wire (3.31 mm²)
Length: 100 feet (30.48 meters)
Current: 15 A (typical household circuit)
Voltage: 120 V (US household)
Type: AC Single-phase
Calculation
V = 2 × I × L × ρ / A
V = 2 × 15 A × 30.48 m × 1.678×10⁻⁸ Ω·m / (3.31×10⁻⁶ m²)
V = 9.16 V × 1.678×10⁻⁸ / 3.31×10⁻⁶
V ≈ 4.64 V (3.87% drop)
This exceeds the 3% recommendation - consider 10 AWG wire.
Voltage Drop Standards
Excellent
Minimal voltage drop
Optimal performance
Acceptable
Within NEC limits
Standard practice
Excessive
Above recommendations
Wire upgrade needed
Common AWG Wire Sizes
Voltage Drop Tips
Minimize wire length when possible
Use larger wire gauge for long runs
Consider parallel conductors for high current
Copper has lower resistance than aluminum
Understanding Voltage Drop in Electrical Systems
What is Voltage Drop?
Voltage drop is the reduction in electrical potential that occurs when current flows through the resistance of conductors. It represents the "loss" of voltage between the source and the load, caused by the inherent resistance of wire materials.
Key Factors
- •Wire Material: Resistivity affects voltage drop
- •Wire Size: Larger cross-section = lower resistance
- •Length: Longer wires = higher resistance
- •Current: Higher current = greater voltage drop
Voltage Drop Formulas
DC/Single-phase AC:
V = 2 × I × L × ρ / (A × n)
Three-phase AC:
V = √3 × I × L × ρ / (A × n)
- V: Voltage drop (volts)
- I: Load current (amperes)
- L: One-way wire length (meters)
- ρ: Wire resistivity (ohm-meters)
- A: Cross-sectional area (m²)
- n: Number of parallel conductors
Consequences of Excessive Voltage Drop
- •Equipment Malfunction: Motors may overheat or fail to start
- •Light Dimming: Incandescent bulbs operate below rated brightness
- •Energy Waste: Power loss as heat in conductors
- •Reduced Efficiency: Equipment operates below optimal performance
Solutions and Best Practices
- Larger Wire Gauge: Reduce resistance with bigger conductors
- Parallel Conductors: Multiple wires reduce effective resistance
- Shorter Runs: Minimize wire length where possible
- Better Materials: Use copper instead of aluminum
- Higher Voltage: Transmit at higher voltage, step down at load
- Load Balancing: Distribute loads across multiple circuits