1. What is a Southwire Wire Size Calculator?

Definition: This calculator determines the minimum wire cross-sectional area needed based on electrical 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 of wire (m²)
• \( \rho \) — Resistivity of conductor 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 acceptable voltage drop over a given length at a specific current.

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:

• Default resistivity is for copper (1.68×10⁻⁸ ohm-m)
• For aluminum, use 2.65×10⁻⁸ ohm-m
• Typical voltage drop limits are 3% for branch circuits, 5% for feeders

5. Frequently Asked Questions (FAQ)

Q1: Why is the resistivity multiplied by 2?
A: The factor of 2 accounts for the round-trip length of the circuit (both hot and neutral wires).

Q2: How do I convert the result to AWG?
A: Use a wire gauge table to find the smallest standard wire size with area ≥ calculated value.

Q3: What's a typical voltage drop allowance?
A: For most applications, 3% voltage drop is recommended for branch circuits.

Q4: Does this account for temperature effects?
A: No, for high-temperature environments, use resistivity values at operating temperature.

Q5: How does wire material affect the calculation?
A: Different materials have different resistivities - copper is most common, aluminum requires larger sizes for same current.