Power Cable Sizing Calculation

Cable Cross-section Formula:

\[ Cross-section (mm²) = \frac{I \times L \times \rho}{V_{drop}} \]

Current (I):

Length (L):

Resistivity (ρ):

Ω·mm²/m

Voltage Drop (V_drop):

Cross-section (mm²):

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1. What is Power Cable Sizing Calculation?

Power cable sizing calculation determines the appropriate cross-sectional area of electrical cables based on current carrying capacity and allowable voltage drop. Proper cable sizing ensures safe and efficient electrical system operation.

2. How Does the Calculator Work?

The calculator uses the cable cross-section formula:

\[ Cross-section (mm²) = \frac{I \times L \times \rho}{V_{drop}} \]

Where:

\( I \) — Current in amperes (A)
\( L \) — Cable length in meters (m)
\( \rho \) — Resistivity of conductor material (Ω·mm²/m)
\( V_{drop} \) — Allowable voltage drop in volts (V)

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

3. Importance of Cable Sizing

Details: Proper cable sizing prevents overheating, reduces energy losses, ensures voltage stability, and maintains electrical safety standards. Undersized cables can cause fires, while oversized cables increase costs unnecessarily.

4. Using the Calculator

Tips: Enter current in amperes, cable length in meters, material resistivity (copper: 0.0175 Ω·mm²/m, aluminum: 0.0283 Ω·mm²/m), and maximum allowable voltage drop. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical resistivity value for copper?
A: Copper has a resistivity of approximately 0.0175 Ω·mm²/m at 20°C.

Q2: What is an acceptable voltage drop?
A: Generally, voltage drop should not exceed 3% for power circuits and 5% for lighting circuits from source to load.

Q3: Does temperature affect cable sizing?
A: Yes, higher temperatures increase resistance. The calculator uses standard temperature values; adjust for high-temperature environments.

Q4: Should I consider future expansion?
A: It's recommended to add 20-25% margin to calculated size for future load increases and safety factors.

Q5: Are there other factors to consider?
A: Yes, installation method, ambient temperature, cable grouping, and short-circuit capacity should also be considered in final cable selection.