1. What is a Voltage Drop Calculator?

Definition: This calculator estimates the voltage drop in an electrical cable based on the material's resistivity, cable length, current, and cross-sectional area.

Purpose: It helps electricians and engineers ensure proper voltage levels at the load end of electrical circuits.

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 cable (meters)
• \( I \) — Current flowing through cable (amps)
• \( A \) — Cross-sectional area of conductor (m²)

Explanation: The formula calculates the voltage loss that occurs due to the resistance of the conductor over its length.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop estimation ensures electrical devices receive adequate voltage for optimal operation and prevents excessive power loss in cables.

4. Using the Calculator

Tips: Enter the resistivity (default 1.68×10⁻⁸ ohm-m for copper), cable length in meters, current in amps, and conductor area in m². All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is there a factor of 2 in the formula?
A: The factor accounts for both the "go" and "return" paths in a single-phase AC or DC circuit.

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 2.82×10⁻⁸ ohm-m.

Q3: What's an acceptable voltage drop?
A: Generally, voltage drop should be less than 3% for branch circuits and 5% for feeder and branch circuits combined.

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

Q5: Does this work for three-phase systems?
A: For balanced three-phase systems, replace the factor 2 with √3 (about 1.732).