1. What is a Whole House Generator Size Calculator?

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

Purpose: It helps homeowners and contractors determine the right generator capacity to power all essential appliances during an outage.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P_{kW} \) — Generator size (kilowatts)
• \( \sum P_{load} \) — Total wattage of all appliances
• \( SF \) — Safety factor (typically 1.25 for residential)

Explanation: The total load in watts 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 your generator can handle all essential loads without being overloaded, while avoiding unnecessary costs for oversized units.

4. Using the Calculator

Tips:

• Add up wattage of all appliances you want to power simultaneously
• Use default safety factor of 1.25 unless you have specific requirements
• Consider both running watts and startup surge watts for motors

5. Frequently Asked Questions (FAQ)

Q1: Why do we need a safety factor?
A: The safety factor accounts for startup surges (especially for motors) and provides capacity for future additions.

Q2: What's included in total load calculation?
A: Include all appliances, lights, and systems you want to power during an outage (HVAC, refrigerator, well pump, etc.).

Q3: When would I change the safety factor?
A: Increase to 1.5 if you have many motor-driven appliances, decrease to 1.1 if only powering resistive loads (lights, heaters).

Q4: How do I find appliance wattage?
A: Check nameplate ratings or use our Appliance Wattage Calculator. Running watts are typically 1/3 of startup watts for motors.

Q5: Should I round up the generator size?
A: Yes, generators come in standard sizes - round up to the nearest available size after calculation.