1. What is a Wire Size Calculator?

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

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( A \) — Cross-sectional area (m²)
• \( \rho \) — Resistivity of wire material (ohm-m)
• \( L \) — Length of wire (meters)
• \( I \) — Current (amps)
• \( VD \) — Maximum allowable voltage drop (volts)

Explanation: The formula calculates the minimum wire size needed to maintain the voltage drop within acceptable limits 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 resistivity (default 1.68×10⁻⁸ ohm-m for copper), wire length in meters, current in amps, and maximum allowed voltage drop. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the default resistivity value for?
A: The default 1.68×10⁻⁸ ohm-m is for copper wire at 20°C. Use 2.65×10⁻⁸ 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 acceptable voltage drop?
A: For most applications, 3% of the supply voltage is acceptable (e.g., 3.6V for 120V circuits).

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

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