1. What is a Volt Drop Calculator for UK?

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

Purpose: It helps electricians and engineers ensure proper voltage levels at load points according to UK electrical regulations.

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 factor of 2 accounts for the return path in single-phase systems. The formula calculates the voltage drop based on conductor properties and circuit parameters.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical equipment receives adequate voltage, prevents performance issues, and complies with UK wiring regulations (BS 7671).

4. Using the Calculator

Tips: Enter the conductor 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: What's the maximum allowed voltage drop in the UK?
A: BS 7671 recommends no more than 3% for lighting circuits and 5% for other circuits at full load.

Q2: Why is resistivity important?
A: Different materials (copper, aluminum) have different resistivities, affecting voltage drop calculations.

Q3: Does this calculator work for three-phase systems?
A: No, this is for single-phase. Three-phase calculations use a different formula (√3 instead of 2).

Q4: How do I convert mm² to m² for cable area?
A: Divide mm² by 1,000,000 (e.g., 2.5mm² = 2.5×10⁻⁶ m²).

Q5: What's the typical resistivity for copper?
A: Approximately 1.68×10⁻⁸ ohm-m at 20°C for pure copper.