1. What is Whole House Generator Sizing?

Whole house generator sizing involves calculating the total power requirements of your home's essential appliances and systems, then adding a safety factor to ensure reliable operation during power outages.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( P_{total} \) — Total generator power required (watts)
• \( \sum P_{loads} \) — Sum of all appliance power requirements
• \( 1.2 \text{ to } 1.5 \) — Safety factor accounting for startup surges and future needs

Explanation: The safety factor ensures your generator can handle momentary startup surges (which can be 2-3 times running wattage) and provides capacity for future additions.

3. Importance of Proper Generator Sizing

Details: Proper sizing prevents overload (which can damage the generator) and under-sizing (which may leave critical systems without power). A correctly sized generator operates efficiently and lasts longer.

4. Using the Calculator

Tips:

• List all essential appliances you want to power during an outage
• Include both running and startup wattage (if known)
• Use 1.35 safety factor for most residential applications
• Consider future needs when selecting generator size

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 temporary surges (2-3x running watts) when motors start.

Q2: Should I size for all appliances or just essentials?
A: Typically size for essential loads (HVAC, fridge, lights, etc.). Whole-house coverage requires careful load management.

Q3: What safety factor should I use?
A: 1.35 is recommended for most homes. Use 1.5 if you expect significant future additions or have motor-heavy loads.

Q4: How do I find appliance wattage?
A: Check nameplates, manuals, or use a clamp meter. Many appliances list amps - multiply by voltage (120V or 240V) to get watts.

Q5: Should I consider generator fuel type?
A: Yes - natural gas generators typically have slightly less output than propane or diesel units of the same size.