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

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 minimize voltage drop in electrical circuits.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( A \) — Wire cross-sectional area (square meters)
• \( \rho \) — Resistivity of wire material (ohm-meters)
• \( L \) — Length of wire (meters)
• \( I \) — Current flowing through wire (amperes)
• \( VD \) — Acceptable voltage drop (volts)

Explanation: The formula calculates the minimum wire size needed to maintain voltage drop within acceptable limits for a given current over a specified distance.

3. Importance of Voltage Drop Calculation

Details: Proper wire sizing ensures efficient power transmission, prevents excessive voltage drop that can affect equipment performance, and reduces energy losses.

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 acceptable voltage drop in volts. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical resistivity for copper wire?
A: Copper has a resistivity of about 1.68×10⁻⁸ ohm-meters at 20°C. For aluminum, use 2.65×10⁻⁸ ohm-meters.

Q2: Why is the length multiplied by 2?
A: The factor of 2 accounts for the round-trip path of the current (out to the load and back).

Q3: What's an acceptable voltage drop?
A: Typically 3% of the supply voltage for branch circuits and 5% for feeders, but consult local electrical codes.

Q4: How do I convert the result to AWG or mm²?
A: Use a wire gauge chart to find the standard size with equal or greater cross-sectional area than your result.

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