1. What is Voltage Drop?

Voltage drop refers to the reduction in voltage in an electrical circuit between the source and load. In South Africa, proper voltage drop calculation is essential for electrical installations to comply with SANS 10142-1 wiring regulations.

2. How Does the Calculator Work?

The calculator uses the standard voltage drop formula:

Where:

• \( VD \) — Voltage drop (Volts)
• \( mV/A/m \) — Millivolts per amp per meter (cable specification)
• \( I \) — Current (Amps)
• \( L \) — Cable length (Meters)

Explanation: The formula calculates how much voltage will be lost over a given cable length based on its specifications and the current flowing through it.

3. Importance of Voltage Drop Calculation

Details: In South Africa, voltage drop must be limited to:

• 5% for fixed installations (lighting circuits)
• 3% for other installations (socket outlets)

Excessive voltage drop can cause equipment malfunction, reduced efficiency, and potential safety hazards.

4. Using the Calculator

Tips:

• Obtain mV/A/m values from cable manufacturer specifications
• Use maximum expected current for accurate calculations
• Measure cable length along the actual route (not straight-line distance)

5. Frequently Asked Questions (FAQ)

Q1: What are typical mV/A/m values for South African cables?
A: Common values range from 18-44 mV/A/m for 2.5mm² cables, depending on type (PVC/PVC, XLPE/SWA, etc.).

Q2: How does South Africa's 230V standard affect voltage drop?
A: The 5% limit means maximum allowed drop is 11.5V for lighting circuits (230V × 5%).

Q3: Should I use single-phase or three-phase values?
A: This calculator uses single-phase values. Three-phase calculations require different formulas.

Q4: Where can I find cable specifications for South African cables?
A: Refer to manufacturer datasheets (e.g., Aberdare, South Ocean, etc.) or SANS standards.

Q5: How does temperature affect voltage drop?
A: Higher temperatures increase resistance and thus voltage drop. Calculations should use values for expected operating temperatures.