1. What is a Voltage Drop Calculator?

Definition: This calculator estimates the voltage drop in electrical circuits according to South African standards.

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

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 drop in a two-wire circuit (hence the factor of 2) based on conductor properties and current.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical equipment receives adequate voltage and complies with SANS 10142-1 wiring regulations.

4. Using the Calculator

Tips: Enter the conductor resistivity (default 1.72×10⁻⁸ ohm-m for copper), length in meters, current in amps, and cross-sectional area in m². All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is voltage drop important?
A: Excessive voltage drop can cause equipment malfunction, overheating, and reduced efficiency.

Q2: What's the maximum allowed voltage drop in South Africa?
A: SANS 10142-1 typically allows 5% voltage drop for lighting circuits and 3% for other circuits.

Q3: What resistivity values should I use?
A: Copper is typically 1.72×10⁻⁸ ohm-m, aluminum is 2.82×10⁻⁸ ohm-m at 20°C.

Q4: Does this account for temperature effects?
A: No, for precise calculations, adjust resistivity for operating temperature.

Q5: How do I convert mm² to m² for conductor area?
A: Divide mm² by 1,000,000 (e.g., 2.5mm² = 2.5×10⁻⁶ m²).