1. What is a Wire Size Calculator?

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

Purpose: It helps electricians and engineers select properly sized wires 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)
• \( V_D \) — Maximum allowable 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, reduces energy loss, minimizes heat generation, and ensures electrical safety.

4. Using the Calculator

Tips: Enter the wire material resistivity (default 1.68×10⁻⁸ ohm-m for copper), wire length, current, and maximum allowable voltage drop. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the default resistivity value?
A: The default is 1.68×10⁻⁸ ohm-m, which is for copper at 20°C. Use 2.82×10⁻⁸ ohm-m for aluminum.

Q2: Why is the length multiplied by 2?
A: The factor of 2 accounts for the round-trip length of the circuit (both hot and neutral wires).

Q3: What's a typical allowable voltage drop?
A: For most applications, 3% of supply voltage is recommended (3.6V for 120V circuits).

Q4: How do I convert m² to AWG?
A: Use a wire gauge table to find the closest standard wire size with area ≥ calculated value.

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