1. What is a Voltage Drop Calculator (UK)?

Definition: This calculator estimates the voltage drop in electrical circuits based on cable properties and current flow, following UK 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 (Ω·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 lost due to the resistance of the cable over its length.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop estimation ensures electrical devices receive adequate voltage and comply with UK wiring regulations (typically ≤3% for lighting, ≤5% for other circuits).

4. Using the Calculator

Tips:

• Default resistivity (1.68×10⁻⁸ Ω·m) is for copper at 20°C
• For aluminum, use 2.82×10⁻⁸ Ω·m
• Length should be one-way distance (multiplied by 2 in formula for return path)
• All values must be > 0

5. Frequently Asked Questions (FAQ)

Q1: Why is the length multiplied by 2?
A: It accounts for both the live and neutral conductors in single-phase circuits (the return path).

Q2: What's the maximum acceptable voltage drop in the UK?
A: BS 7671 recommends ≤3% for lighting circuits and ≤5% for other circuits at full load.

Q3: How does temperature affect the calculation?
A: Higher temperatures increase resistivity. For precise calculations, adjust ρ for operating temperature.

Q4: What about three-phase systems?
A: For balanced three-phase systems, replace the 2 with √3 (1.732) in the formula.

Q5: 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).