1. What is a Voltage Drop Calculator?

Definition: This calculator estimates the voltage drop in an electrical circuit based on current, conductor length, and resistance.

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

2. How Does the Calculator Work?

The calculator uses the Southwire voltage drop formula:

Where:

• \( VD \) — Voltage drop (volts)
• \( I \) — Current (amps)
• \( L \) — Length of conductor (feet)
• \( R \) — Resistance (ohms per 1000 feet)

Explanation: The formula accounts for both the outgoing and return paths (hence the factor of 2) in a single-phase circuit.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical equipment receives adequate voltage for optimal performance and prevents excessive power loss.

4. Using the Calculator

Tips: Enter the current in amps, conductor length in feet, and resistance in ohms per 1000 feet. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the resistance divided by 1000?
A: Because conductor resistance is typically specified per 1000 feet in wire specifications.

Q2: Does this work for three-phase systems?
A: No, this formula is for single-phase systems. Three-phase calculations use a different formula.

Q3: Where can I find resistance values?
A: Consult wire manufacturer specifications or NEC tables for resistance values of different wire gauges.

Q4: What's an acceptable voltage drop?
A: Typically 3% for branch circuits and 5% for feeder circuits, but check local electrical codes.

Q5: Does temperature affect the calculation?
A: Yes, resistance changes with temperature. Use resistance values appropriate for your operating conditions.