Power Cable Size Calculator

Cable Size Formula:

\[ Cable\ Size = \sqrt{\frac{Power \times Length \times 1000}{V \times Drop\ \% \times k}} \ (approx),\ Ampacity-based\ sizing. \]

Power (watts):

Length (m):

Voltage (V):

Drop % (%):

Constant (k):

Cable Size (mm²):

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1. What is the Power Cable Size Calculator?

The Power Cable Size Calculator helps determine the appropriate cable cross-sectional area based on electrical parameters to ensure safe and efficient power transmission while minimizing voltage drop.

2. How Does the Calculator Work?

The calculator uses the cable size formula:

\[ Cable\ Size = \sqrt{\frac{Power \times Length \times 1000}{V \times Drop\ \% \times k}} \]

Where:

\( Power \) — Electrical power in watts (W)
\( Length \) — Cable length in meters (m)
\( V \) — Voltage in volts (V)
\( Drop\ \% \) — Maximum allowable voltage drop percentage (%)
\( k \) — Conductivity constant (depends on material and temperature)

Explanation: This formula calculates the minimum cable cross-sectional area required to limit voltage drop to acceptable levels while considering ampacity requirements.

3. Importance of Cable Size Calculation

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

4. Using the Calculator

Tips: Enter power in watts, length in meters, voltage in volts, maximum voltage drop percentage, and the conductivity constant. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical value for constant k?
A: For copper conductors at 75°C, k is approximately 0.0217. For aluminum, it's around 0.035. Always consult manufacturer specifications for precise values.

Q2: What is an acceptable voltage drop percentage?
A: Generally, 3% for branch circuits and 5% for feeder circuits is acceptable, but local electrical codes may specify different requirements.

Q3: Why consider both voltage drop and ampacity?
A: Voltage drop ensures proper equipment operation, while ampacity prevents cable overheating. Always use the larger size from both calculations.

Q4: How does temperature affect cable sizing?
A: Higher temperatures reduce current-carrying capacity. Derating factors must be applied for installations in high-temperature environments.

Q5: Should I round up the calculated cable size?
A: Yes, always round up to the next available standard cable size to ensure safety margins and account for future load increases.