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 plus a safety margin. Undersizing can lead to overload while oversizing is inefficient and costly.

2. How Does the Calculator Work?

The calculator uses the generator sizing formula:

Where:

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

Explanation: The safety factor accounts for motor startup surges (which can be 3-7x running watts) and provides headroom for future additions.

3. Importance of Proper Generator Sizing

Details: Correct sizing ensures your generator can handle all essential loads without overload while operating efficiently. Oversizing leads to "wet stacking" in diesel generators and poor efficiency in all types.

4. Using the Calculator

Tips:

1. Calculate your total connected load by adding wattages of all appliances you want to power
2. Choose safety factor: 1.2 for minimal loads, 1.35 for typical homes, 1.5 for heavy motor loads
3. Consider both running watts and startup watts for motors (AC, fridge, etc.)

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between running and starting watts?
A: Running watts are continuous power needs. Starting watts are temporary surges (2-3 seconds) needed when motors start, typically 3-7x higher.

Q2: How do I find my appliances' wattage?
A: Check nameplates or manuals. Alternatively, use: Watts = Volts × Amps (for 120V devices: amps × 120 = watts).

Q3: Should I size for all-house or essential loads only?
A: For whole-house, sum all circuits. For essential circuits only, sum just those loads (typically 5,000-10,000W).

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

Q5: Does generator type affect sizing?
A: Inverter generators handle surges better and can sometimes be sized closer to running loads than conventional generators.