1. What is Generator Sizing Calculation?

The generator sizing calculation determines the appropriate wattage capacity needed for a backup generator based on your home's electrical loads. It ensures your generator can handle all connected devices with a safety margin.

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 (20% to 50% margin)

Explanation: The safety factor accounts for startup surges, future additions, and ensures the generator isn't running at full capacity continuously.

3. Importance of Proper Generator Sizing

Details: Proper sizing prevents generator overload (which can cause failure) and underutilization (which wastes money). It ensures reliable power during outages while extending generator lifespan.

4. Using the Calculator

Tips:

• Calculate or measure the wattage of all devices you want to power simultaneously
• Choose safety factor: 1.2 for minimal margin, 1.5 for heavy appliances or future expansion
• The result is the minimum generator capacity you should consider

5. Frequently Asked Questions (FAQ)

Q1: How do I find my appliances' wattage?
A: Check manufacturer labels or manuals. Many appliances list running watts and starting watts (use the higher value for motors).

Q2: What's the difference between running and starting watts?
A: Some appliances (like refrigerators) need 2-3 times more power to start than to run continuously. Always account for startup surges.

Q3: Should I size for all-house or selective circuits?
A: This calculator works for both approaches. For whole-house, sum all circuits. For selective, sum only essential circuits.

Q4: What if I have large motor loads (AC, well pump)?
A: Use the higher safety factor (1.5) and verify the generator can handle the starting surge (locked rotor amps).

Q5: How does generator fuel type affect sizing?
A: Fuel type doesn't change sizing, but propane/natural gas generators typically produce 10-20% less power at higher elevations.