1. What is Voltage Drop?

Voltage drop is the reduction in voltage in an electrical circuit between the source and load. In the UK, it's important to calculate voltage drop to ensure electrical installations comply with BS 7671 regulations and that equipment operates correctly.

2. How Does the Calculator Work?

The calculator uses the voltage drop equation:

Where:

• \( VD \) — Voltage drop (volts)
• \( I \) — Current (amperes)
• \( L \) — Length of cable (meters)
• \( R \) — Resistance per unit length (millivolts per ampere per meter)

Explanation: The equation calculates the voltage loss that occurs due to the resistance of the cable when current flows through it.

3. Importance of Voltage Drop Calculation

Details: Calculating voltage drop is crucial for electrical safety and compliance. Excessive voltage drop can lead to equipment malfunction, reduced efficiency, and potential safety hazards.

4. Using the Calculator

Tips: Enter the current in amperes, cable length in meters, and cable resistance in mV/A/m. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the maximum allowed voltage drop in the UK?
A: For lighting circuits, 3% of supply voltage. For other circuits, 5% of supply voltage (BS 7671 regulations).

Q2: How do I find the resistance value for my cable?
A: Refer to manufacturer specifications or standard tables in the IET Wiring Regulations (BS 7671).

Q3: Does voltage drop calculation differ for DC circuits?
A: The same formula applies, but resistance values may differ for DC applications.

Q4: How does temperature affect voltage drop?
A: Higher temperatures increase cable resistance, which increases voltage drop. Calculations should account for operating temperature.

Q5: Can I use this for three-phase calculations?
A: This calculator is for single-phase. Three-phase calculations require a different approach (multiply by √3).