1. What is a Voltage Drop Cable Size Calculator?

Definition: This calculator determines the minimum cable cross-sectional area required to limit voltage drop in electrical circuits.

Purpose: It helps electricians and engineers select appropriate cable sizes to ensure proper voltage levels at load points.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The formula calculates the minimum conductor size needed to maintain voltage within acceptable limits over a given distance.

3. Importance of Voltage Drop Calculation

Details: Proper cable sizing ensures electrical equipment operates efficiently, prevents excessive power loss, and meets electrical code requirements.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Why is the resistivity value multiplied by 2?
A: The factor of 2 accounts for the round-trip path of current (both the outgoing and return conductors).

Q2: What's a typical resistivity value for copper?
A: Copper has a resistivity of about 1.68×10⁻⁸ ohm-m at 20°C. For aluminum, use 2.65×10⁻⁸ ohm-m.

Q3: What's an acceptable voltage drop?
A: Most electrical codes recommend limiting voltage drop to 3% for branch circuits and 5% for feeder circuits.

Q4: How does temperature affect the calculation?
A: Higher temperatures increase resistivity. For precise calculations, use resistivity values at operating temperature.

Q5: How do I convert the result to AWG or mm²?
A: Use standard wire gauge tables to find the nearest standard size equal to or larger than your calculated area.