1. What is a Generator Size Calculator?

Definition: This calculator estimates the appropriate generator size (in kW) needed to power a house based on total electrical load and a safety factor.

Purpose: Helps homeowners and electricians determine the right generator capacity for residential backup power needs.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P_{kW} \) — Generator size (kilowatts)
• \( \Sigma P_{load} \) — Total electrical load (watts)
• \( SF \) — Safety factor (typically 1.25-1.5)

Explanation: The total wattage is converted to kilowatts (divided by 1000) then multiplied by a safety factor to account for startup surges and future needs.

3. Importance of Proper Generator Sizing

Details: Correct sizing ensures reliable power during outages, prevents overloading, and maximizes fuel efficiency.

4. Using the Calculator

Tips:

• Calculate your total load by summing all essential appliances' wattage
• Use 1.25 as default safety factor (adjust up to 1.5 for heavy motor loads)
• Average home needs 5-20 kW depending on size and appliances

5. Frequently Asked Questions (FAQ)

Q1: What's included in total load calculation?
A: Sum of all essential appliances - lights, fridge, HVAC (if powering), well pump, etc.

Q2: Why is the safety factor important?
A: It accounts for motor startup surges (which can be 3x running watts) and future needs.

Q3: What's a typical generator size for homes?
A: Most homes need 5-20 kW. Small homes: 5-10 kW, medium: 10-15 kW, large: 15-20+ kW.

Q4: Should I size for all appliances or just essentials?
A: Typically size for essentials, unless you need whole-house coverage (requires larger generator).

Q5: How do I find appliance wattages?
A: Check nameplates or manuals, or use our Appliance Wattage Calculator tool.