1. What is a Voltage Drop Calculator?

Definition: This calculator estimates the voltage drop in an electrical circuit based on conductor properties and current flow.

Purpose: It helps electricians and engineers ensure proper voltage levels in electrical installations by predicting voltage loss.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The formula calculates the voltage lost due to conductor resistance over a specific length carrying a certain current.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop estimation ensures electrical devices receive adequate voltage for optimal operation and prevents performance issues.

4. Using the Calculator

Tips: Enter the conductor resistivity (default 1.68×10⁻⁸ ohm-m for copper), length, current, and cross-sectional area. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is there a factor of 2 in the formula?
A: The factor of 2 accounts for the round-trip path of current (both "hot" and "neutral" wires in AC circuits).

Q2: What's the typical resistivity for copper?
A: Copper has a resistivity of about 1.68×10⁻⁸ ohm-m at 20°C. Aluminum is about 2.65×10⁻⁸ ohm-m.

Q3: How does temperature affect the calculation?
A: Resistivity increases with temperature. For precise calculations, use resistivity values at operating temperature.

Q4: What's an acceptable voltage drop?
A: Typically less than 3% for branch circuits and 5% for feeder and branch circuits combined (NEC recommendations).

Q5: How do I convert wire gauge to cross-sectional area?
A: Use standard AWG tables or our Wire Gauge Calculator tool for conversions.