1. What is Generator Sizing?

Generator sizing is the process of determining the appropriate wattage capacity for a home generator based on your electrical loads and a safety factor. Proper sizing ensures your generator can handle all connected devices without overload.

2. How Does the Calculator Work?

The calculator uses the generator sizing formula:

Where:

• \( P_{total} \) — Recommended generator size in watts
• \( \Sigma P_{loads} \) — Sum of all connected electrical loads in watts
• 1.2 to 1.5 — Safety factor accounting for startup surges and future expansion

Explanation: The safety factor accounts for motor startup currents (which can be 3-7 times running current) and provides headroom for additional loads.

3. Importance of Proper Generator Sizing

Details: Undersized generators can overload and fail, while oversized generators operate inefficiently and cost more. Proper sizing ensures reliable power during outages and extends generator life.

4. Using the Calculator

Tips:

• Calculate your total connected load by adding wattages of all devices you want to power
• Choose safety factor: 1.2 for minimal loads, 1.35 for average, 1.5 for heavy motor loads
• For motor loads (AC, fridge, etc.), use the starting wattage if known

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between running and starting watts?
A: Running watts are continuous power needs, while starting watts are the extra power needed for 2-3 seconds when motors start (typically 3-7× running watts).

Q2: Should I size for all loads or just essentials?
A: This depends on your needs. For whole-house coverage, include all loads. For emergency essentials only, calculate just those circuits.

Q3: How do I find my appliance wattages?
A: Check nameplates, manuals, or use a wattage meter. Common references: fridge (600-800W), central AC (2000-5000W), lights (60-100W each).

Q4: What safety factor should I choose?
A: 1.2 for mostly resistive loads (lights, electronics), 1.35 for mixed loads, 1.5 for heavy motor loads (well pumps, air conditioners).

Q5: Should I round up to standard generator sizes?
A: Yes, generators come in standard sizes (3000W, 5000W, 7500W, etc.). Always round up to the next available size after calculation.