1. What is the 3-Phase Wire Size Formula?

The 3-phase motor wire size formula calculates the minimum cross-sectional area of wire needed to safely carry current over a specified distance while maintaining acceptable voltage drop. Proper wire sizing is critical for motor performance and safety.

2. How Does the Calculator Work?

The calculator uses the 3-phase wire size formula:

Where:

• \( A \) — Cross-sectional area of wire (mm²)
• \( I \) — Current in amps
• \( L \) — Length of wire in meters
• \( \rho \) — Resistivity of wire material (Ω·m)
• \( Vd \) — Maximum allowable voltage drop in volts

Explanation: The formula accounts for current requirements, distance, material properties, and acceptable voltage drop to determine minimum wire size.

3. Importance of Proper Wire Sizing

Details: Correct wire sizing prevents excessive voltage drop (which can cause motor overheating and reduced efficiency), minimizes power loss, and ensures safe operation by preventing overheating of conductors.

4. Using the Calculator

Tips: Enter current in amps, length in meters, resistivity in Ω·m (default is for copper), and desired maximum voltage drop. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical resistivity value for copper?
A: Copper resistivity is approximately 0.00000172 Ω·m at 20°C (default value in calculator).

Q2: What's an acceptable voltage drop for motors?
A: Generally 3% or less of supply voltage is recommended (default 3V assumes 100V system).

Q3: Does this account for temperature effects?
A: No, for high temperature environments, use adjusted resistivity values or consult standards.

Q4: How does this differ from single-phase calculation?
A: Single-phase uses different constants and typically requires larger wire for same current/distance.

Q5: Should I round up the calculated wire size?
A: Yes, always round up to nearest standard wire size available in your region.