Generator Wire Size Calculator

Wire Size Formula:

\[ A_w = \frac{I \times L \times K}{V_{drop} \times \sigma} \]

Current (I):

amps

Length (L):

feet

Factor (K):

(constant)

Voltage Drop (V_drop):

volts

Conductivity (σ):

Ω⁻¹·mm²/m

Wire Size (A_w):

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1. What is a Generator Wire Size Calculator?

Definition: This calculator determines the appropriate wire size (cross-sectional area) for generator installations based on current, distance, and allowable voltage drop.

Purpose: It helps electricians and engineers select the correct wire gauge to ensure safe and efficient power transmission from generators.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ A_w = \frac{I \times L \times K}{V_{drop} \times \sigma} \]

Where:

\( A_w \) — Wire cross-sectional area (mm²)
\( I \) — Current (amps)
\( L \) — Length of wire (feet)
\( K \) — Conversion factor (12.9 for single-phase, 21.6 for three-phase)
\( V_{drop} \) — Allowable voltage drop (volts)
\( \sigma \) — Conductivity of copper (58 Ω⁻¹·mm²/m)

Explanation: The formula calculates the minimum wire size needed to maintain voltage drop within acceptable limits for a given current over a specific distance.

3. Importance of Proper Wire Sizing

Details: Correct wire sizing prevents excessive voltage drop, reduces power loss, minimizes heat generation, and ensures safe operation of electrical systems.

4. Using the Calculator

Tips: Enter the current in amps, wire length in feet, factor (default 12.9 for single-phase), allowable voltage drop (default 3V), and conductivity (default 58 for copper). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical allowable voltage drop?
A: For most applications, 3% voltage drop is acceptable (3.6V for 120V systems, 6V for 240V systems).

Q2: When should I use the three-phase factor (21.6)?
A: Use 21.6 when calculating wire size for three-phase generator systems.

Q3: What conductivity value should I use for aluminum wire?
A: Use approximately 35 Ω⁻¹·mm²/m for aluminum conductors.

Q4: How do I convert mm² to AWG?
A: Refer to wire gauge conversion charts (e.g., 2.5mm² ≈ AWG 14, 4mm² ≈ AWG 12).

Q5: Does this account for ambient temperature?
A: No, for high-temperature environments, consult NEC ampacity tables for derating factors.