1. What is SWA Cable Voltage Drop Calculator?

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

Purpose: It helps electricians and engineers 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 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:

• Default resistivity for copper is 1.72×10⁻⁸ Ω·m
• For aluminum, use 2.82×10⁻⁸ Ω·m
• Length should be one-way distance (multiplied by 2 in formula)
• Cross-sectional area must be in square meters

5. Frequently Asked Questions (FAQ)

Q1: Why multiply by 2 in the formula?
A: The factor of 2 accounts for the return path in single-phase AC or DC circuits (total cable length is twice the one-way distance).

Q2: What's the acceptable voltage drop?
A: Typically 3% for lighting circuits and 5% for other circuits, but check local regulations.

Q3: How do I convert cable size from mm² to m²?
A: Divide mm² by 1,000,000 (e.g., 10 mm² = 0.00001 m²).

Q4: Does this apply to three-phase systems?
A: For balanced three-phase systems, replace the 2 with √3 (1.732).

Q5: What affects resistivity (ρ)?
A: Material type (copper/aluminum) and temperature (higher temp increases ρ).