1. What is a Wire Size and Length Calculator?

Definition: This calculator determines the maximum length of wire that can be used while maintaining acceptable voltage drop based on wire properties and current.

Purpose: It helps electricians and engineers design electrical systems with proper voltage levels at the load.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The formula calculates the maximum length before voltage drop exceeds specifications, considering both out and return paths (hence the factor of 2).

3. Importance of Wire Length Calculation

Details: Proper wire sizing ensures adequate voltage at the load, prevents overheating, and maintains system efficiency.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Why is resistivity important?
A: Different materials (copper, aluminum) have different resistivities, affecting how much voltage drops over distance.

Q2: What's a typical voltage drop allowance?
A: For most circuits, 3% of supply voltage is common (e.g., 3.6V drop on a 120V circuit).

Q3: How do I find wire cross-sectional area?
A: For round wires, A = π × (diameter/2)². AWG sizes have standard area values.

Q4: Why the factor of 2 in the formula?
A: It accounts for both the outgoing and return paths in a circuit (total wire length is 2×L).

Q5: Does this include safety margins?
A: No, consider using 80% of calculated length for additional safety margin.