Calculate Swa Cable Size

SWA Cable Size Formula:

\[ A = \frac{2 \times L \times I \times \rho}{Vd} \]

Cable Length (L):

Current (I):

Resistivity (ρ):

Ω·m

Voltage Drop (Vd):

Cable Cross-Sectional Area (A):

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1. What is the SWA Cable Size Calculation?

The SWA (Steel Wire Armoured) cable size calculation determines the appropriate cross-sectional area of a cable based on voltage drop requirements. This ensures proper electrical performance and safety in power distribution systems.

2. How Does the Calculator Work?

The calculator uses the voltage drop formula:

\[ A = \frac{2 \times L \times I \times \rho}{Vd} \]

Where:

\( A \) — Cable cross-sectional area (mm²)
\( L \) — Cable length (m)
\( I \) — Current (A)
\( \rho \) — Resistivity of conductor material (Ω·m)
\( Vd \) — Permissible voltage drop (V)

Explanation: The formula calculates the minimum cable size required to maintain voltage drop within acceptable limits for a given current and cable length.

3. Importance of Cable Sizing

Details: Proper cable sizing is crucial for electrical safety, preventing overheating, ensuring voltage stability, and complying with electrical codes and standards.

4. Using the Calculator

Tips: Enter cable length in meters, current in amperes, resistivity in ohm-meters (default is 1.724e-8 for copper), and permissible voltage drop in volts. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical resistivity value for copper?
A: The resistivity of copper at 20°C is approximately 1.724 × 10⁻⁸ Ω·m.

Q2: Why is voltage drop important in cable sizing?
A: Excessive voltage drop can cause equipment malfunction, reduced efficiency, and potential safety hazards in electrical systems.

Q3: What factors affect cable sizing besides voltage drop?
A: Current carrying capacity, ambient temperature, installation method, and short-circuit capacity also influence cable sizing decisions.

Q4: How does cable length affect the required size?
A: Longer cable lengths require larger cross-sectional areas to maintain the same voltage drop for a given current.

Q5: Are there standard cable sizes available?
A: Yes, cables are manufactured in standard sizes (e.g., 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95 mm²) and the calculated size should be rounded up to the nearest standard size.