1. What is a Wire Size and Voltage Drop Calculator?

Definition: This calculator determines the required wire cross-sectional area based on electrical current, wire length, material resistivity, and acceptable voltage drop.

Purpose: It helps electricians and engineers select proper wire sizes to ensure safe and efficient electrical installations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( A \) — Cross-sectional area of wire (m²)
• \( \rho \) — Resistivity of wire material (ohm-m)
• \( L \) — Length of wire (meters)
• \( I \) — Current flowing through wire (amps)
• \( V_D \) — Acceptable voltage drop (volts)

Explanation: The formula calculates the minimum wire size needed to limit voltage drop to an acceptable level for a given current over a specified distance.

3. Importance of Proper Wire Sizing

Details: Correct wire sizing prevents excessive voltage drop (which can cause equipment malfunction), reduces energy loss, and minimizes fire hazards from overheating.

4. Using the Calculator

Tips: Enter the wire material resistivity (default 1.68×10⁻⁸ ohm-m for copper), wire length in meters, current in amps, and maximum acceptable voltage drop in volts.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical resistivity value for copper?
A: Pure copper at 20°C has ρ ≈ 1.68×10⁻⁸ ohm-m. For aluminum, use 2.65×10⁻⁸ ohm-m.

Q2: Why is the length multiplied by 2 in the formula?
A: The factor of 2 accounts for the round-trip path of current (both "hot" and "neutral" wires in AC circuits).

Q3: What's an acceptable voltage drop?
A: For most applications, 3% of supply voltage is recommended (e.g., 3.6V for 120V circuits).

Q4: How do I convert m² to AWG wire size?
A: Use an AWG conversion chart after calculating the area. The calculator provides the area in m².

Q5: Does this account for temperature effects?
A: No, for high-temperature environments, use resistivity values at the expected operating temperature.