1. What is SWA Cable Voltage Drop?

Definition: This calculator estimates the voltage drop in Steel Wire Armored (SWA) cables based on cable properties and electrical load.

Purpose: It helps electricians and engineers ensure proper voltage levels at the load end of electrical circuits.

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 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 calculation ensures electrical equipment receives adequate voltage for proper operation and prevents excessive power loss.

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 cross-sectional 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 of 2 accounts for the return path in single-phase AC or DC circuits (the total cable length is twice the one-way distance).

Q2: What's the typical resistivity for copper?
A: Copper has resistivity of about 1.68×10⁻⁸ ohm-m at 20°C. For aluminum, use 2.82×10⁻⁸ ohm-m.

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

Q4: What's an acceptable voltage drop?
A: Typically 3% for lighting circuits and 5% for other circuits, but check local regulations.

Q5: How do I convert cable size from mm² to m²?
A: Divide mm² by 1,000,000 (e.g., 10 mm² = 0.00001 m²).