1. What is a Commercial Generator Sizing Calculator?

Definition: This calculator estimates the required generator size in kilowatts based on the total electrical load and a safety factor.

Purpose: It helps facility managers, electricians, and engineers properly size generators for commercial applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P_{kW} \) — Generator size (kilowatts)
• \( \Sigma P_{load} \) — Total connected load (watts)
• \( SF \) — Safety factor (typically 1.25 for commercial applications)

Explanation: The total load is converted from watts to kilowatts, then multiplied by a safety factor to account for startup surges and future expansion.

3. Importance of Proper Generator Sizing

Details: Correct generator sizing ensures reliable power during outages, prevents overload conditions, and optimizes fuel efficiency.

4. Using the Calculator

Tips: Enter the total connected load in watts and safety factor (default 1.25). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is a safety factor needed?
A: The safety factor accounts for motor starting currents, future load additions, and ensures the generator isn't constantly running at full capacity.

Q2: What's a typical safety factor?
A: Commercial applications typically use 1.25-1.5, while critical facilities may use higher factors.

Q3: How do I determine total connected load?
A: Sum the nameplate ratings of all equipment that might run simultaneously, or perform an electrical load study.

Q4: Should I include all building loads?
A: Only include essential loads that need backup power during an outage, unless designing for full building backup.

Q5: Does this account for three-phase power?
A: This provides a basic kW estimate. For three-phase systems, consult an electrical engineer for precise sizing.