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

Definition: This calculator estimates the voltage drop in a DC electrical circuit based on cable properties and current.

Purpose: It helps electricians and engineers ensure proper voltage levels at the load end of DC circuits, complying with UK electrical standards.

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 for both the outgoing and return paths (hence the factor of 2).

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical devices receive sufficient voltage to operate correctly and helps prevent energy waste and overheating.

4. Using the Calculator

Tips: Enter the conductor resistivity (default 1.68×10⁻⁸ Ω·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 outgoing and return paths in a DC circuit (total cable length is twice the one-way distance).

Q2: What's the typical resistivity value for copper?
A: Copper has a resistivity of approximately 1.68×10⁻⁸ Ω·m at 20°C. For aluminum, use 2.82×10⁻⁸ Ω·m.

Q3: What's the maximum acceptable voltage drop?
A: UK regulations typically recommend no more than 3% voltage drop for lighting circuits and 5% for other circuits.

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

Q5: Does temperature affect the calculation?
A: Yes, resistivity increases with temperature. For precise calculations at different temperatures, adjust the resistivity value accordingly.