1. What is a Copper Wire Voltage Drop Calculator?

Definition: This calculator estimates the voltage drop in copper wires based on length, current, cross-sectional area, and copper's resistivity.

Purpose: It helps electricians and engineers ensure proper voltage levels in electrical circuits by accounting for resistance in copper wiring.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( VD \) — Voltage drop (volts)
• \( \rho_{cu} \) — Copper resistivity (Ω·m, default 1.68×10⁻⁸)
• \( L \) — Wire length (meters)
• \( I \) — Current (amperes)
• \( A \) — Cross-sectional area (m²)

Explanation: The factor of 2 accounts for the round-trip path of the circuit (both hot and neutral wires).

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop estimation ensures electrical devices receive adequate voltage, prevents energy waste, and maintains system efficiency.

4. Using the Calculator

Tips: Enter wire length in meters, current in amps, cross-sectional area in m², and copper resistivity (default 1.68×10⁻⁸ Ω·m). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is copper resistivity important?
A: Copper's low resistivity (1.68×10⁻⁸ Ω·m) makes it an excellent conductor, but voltage drop still occurs over long distances or with high currents.

Q2: How do I find the cross-sectional area?
A: For round wires, use \( A = \pi r^2 \) where r is the radius. AWG sizes have standard cross-sectional areas.

Q3: When is voltage drop a concern?
A: Generally when the drop exceeds 3% for branch circuits or 5% for feeder circuits (NEC recommendations).

Q4: Does temperature affect the calculation?
A: Yes, copper's resistivity increases with temperature. For precise calculations, adjust resistivity for operating temperature.

Q5: Why the factor of 2 in the formula?
A: It accounts for both the "hot" and "neutral" wires in a typical circuit (the round-trip path of current).