1. What is a Voltage Drop Calculator Over Cable Length?

Definition: This calculator estimates the voltage drop across an electrical cable based on its material properties, length, current, and cross-sectional area.

Purpose: It helps electrical engineers and technicians ensure proper voltage levels at load points in 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 factor of 2 accounts for the return path in DC or single-phase AC circuits. The voltage drop increases with cable length and current, but decreases with larger conductor area.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical devices receive adequate voltage, prevents excessive power loss, and maintains system efficiency.

4. Using the Calculator

Tips:

• Default resistivity (1.68×10⁻⁸ Ω·m) is for copper at 20°C
• For aluminum conductors, use 2.82×10⁻⁸ Ω·m
• For three-phase systems, replace the factor 2 with √3 (1.732)

5. Frequently Asked Questions (FAQ)

Q1: Why is voltage drop important?
A: Excessive voltage drop can cause equipment malfunction, reduced efficiency, and overheating of conductors.

Q2: What's an acceptable voltage drop?
A: Typically 3% for branch circuits and 5% for feeder circuits, but check local electrical codes.

Q3: Does this formula work for AC and DC?
A: This is the DC formula. For AC, additional factors like power factor and skin effect may apply.

Q4: How do I find cable cross-sectional area?
A: For round wires: \( A = \pi \times r^2 \) where r is radius in meters.

Q5: What affects conductor resistivity?
A: Material type and temperature (resistivity increases with temperature).