Calculate Cable Size

Cable Size Formula:

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

Length (L):

Current (I):

Resistivity (ρ):

Ω·m

Voltage Drop (Vd):

Cross-Sectional Area (A):

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1. What is the Cable Size Formula?

The cable size formula calculates the required cross-sectional area of an electrical cable based on length, current, resistivity, and allowable voltage drop. It ensures proper electrical performance and safety in wiring installations.

2. How Does the Calculator Work?

The calculator uses the cable size formula:

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

Where:

\( A \) — Cross-sectional area (mm²)
\( L \) — Length of the cable (m)
\( I \) — Current flowing through the cable (A)
\( \rho \) — Resistivity of the conductor material (Ω·m)
\( Vd \) — Allowable voltage drop (V)

Explanation: The formula calculates the minimum cross-sectional area needed to maintain voltage drop within acceptable limits for a given current and cable length.

3. Importance of Cable Size Calculation

Details: Proper cable sizing is essential for electrical safety, preventing overheating, ensuring efficient power transmission, and maintaining voltage stability in electrical systems.

4. Using the Calculator

Tips: Enter cable length in meters, current in amperes, resistivity in ohm-meters, and allowable 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 is approximately 1.68 × 10⁻⁸ Ω·m at 20°C.

Q2: Why is voltage drop important in cable sizing?
A: Excessive voltage drop can lead to inefficient operation of electrical equipment and potential damage to motors and other devices.

Q3: What factors affect cable size selection?
A: Current carrying capacity, voltage drop limitations, installation method, ambient temperature, and cable material all influence cable size selection.

Q4: How does cable length affect size requirements?
A: Longer cable runs 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., 1.5mm², 2.5mm², 4mm², 6mm², etc.) and the calculated size should be rounded up to the nearest available standard size.