Wire Size Calculator Southwire

Southwire Equation:

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

Length (L):

Current (I):

Resistivity (ρ):

Ω·m

Voltage Drop (Vd):

Wire Size (A):

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1. What Is The Southwire Wire Size Calculation?

The Southwire wire size calculation determines the appropriate cross-sectional area of electrical wire needed to maintain acceptable voltage drop levels over a specified distance, ensuring efficient power transmission and electrical safety.

2. How Does The Calculator Work?

The calculator uses the Southwire equation:

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

Where:

\( A \) — Wire cross-sectional area (mm²)
\( L \) — Length of the wire (m)
\( I \) — Current flowing through the wire (A)
\( \rho \) — Resistivity of the wire material (Ω·m)
\( Vd \) — Acceptable voltage drop (V)

Explanation: This equation calculates the minimum wire size required to maintain voltage drop within acceptable limits, considering the wire's length, current load, material properties, and maximum allowable voltage drop.

3. Importance Of Proper Wire Sizing

Details: Proper wire sizing is critical for electrical safety, preventing overheating, minimizing energy loss, ensuring equipment operates correctly, and complying with electrical codes and standards.

4. Using The Calculator

Tips: Enter wire length in meters, current in amperes, resistivity in ohm-meters (copper is typically 1.68×10⁻⁸ Ω·m), and acceptable voltage drop in volts. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is voltage drop important in wire sizing?
A: Excessive voltage drop can cause equipment malfunction, reduced efficiency, and potential safety hazards by causing wires to overheat.

Q2: What is the typical resistivity value for copper wire?
A: Copper wire typically has a resistivity of approximately 1.68×10⁻⁸ Ω·m at 20°C.

Q3: How does wire length affect the required size?
A: Longer wire runs require larger wire sizes to maintain the same voltage drop percentage, as resistance increases with length.

Q4: What are acceptable voltage drop limits?
A: Most electrical codes recommend voltage drop not exceed 3% for branch circuits and 5% for feeder circuits to ensure proper equipment operation.

Q5: Does this calculation account for temperature variations?
A: The basic calculation uses standard resistivity values. For precise applications, temperature correction factors may need to be applied as resistivity changes with temperature.