Installation & Sizing Guide: Getting the Right Generator for Your Home
Selecting the right size generator and ensuring proper installation are crucial steps in creating a reliable backup power system for your home. A properly sized and installed generator provides peace of mind during outages without unnecessary expense or complications.
This guide covers the essential factors to consider when sizing your generator and what to expect during the installation process.
Part 1: How to Size Your Generator Correctly
Why Proper Sizing Matters
An undersized generator can't handle your power needs and may shut down from overload during critical moments. Conversely, an oversized unit costs more upfront, consumes more fuel, and may run inefficiently. Finding the right balance is essential for reliability and value.
Quick Sizing Guide by House Size
| House Size | Typical Generator Size | What It Powers |
|---|---|---|
| Up to 1,500 sq ft | 8-12 kW | Essentials only (lights, refrigerator, select circuits) |
| 1,500-2,500 sq ft | 14-16 kW | Essentials plus small AC or heat pump |
| 2,500-3,500 sq ft | 18-22 kW | Most appliances including central AC (one zone) |
| 3,500+ sq ft | 24-48 kW | Whole-home coverage with multiple AC zones |
Note: These are estimates. Your actual needs may vary based on specific appliances.
5-Step Sizing Process
List Essential Appliances
Identify what you absolutely need during an outage (refrigerator, heating/cooling, medical equipment, well pump, etc.).
Calculate Running Wattage
Add up the running watts of all appliances you want to power simultaneously.
Account for Starting Watts
Motors need 2-3× more power to start than to run. Include the highest startup requirement in your calculations.
Add 20% Buffer
Include extra capacity for future needs and to avoid running your generator at maximum load.
Consider Load Management
Some systems can automatically prioritize essential items, allowing you to use a smaller generator.
Pro Tip: Use our Generator Sizing Calculator for a precise recommendation based on your specific appliances and needs.
Part 2: The Installation Process
Installing a standby generator is not a DIY project. It requires professional expertise to ensure safety, code compliance, and proper operation. Here's what the process typically involves:
Installation Steps
Site Assessment & Preparation
A professional evaluates your home's electrical needs, selects an installation location that meets code requirements, and prepares the site.
Permit Acquisition
Your installer obtains necessary permits from local authorities. This may include electrical, mechanical, and zoning permits.
Foundation Installation
A concrete pad or composite base is installed to provide a stable, level foundation for the generator.
Generator & Transfer Switch Placement
The generator is positioned on the foundation and the automatic transfer switch is installed near your electrical panel.
Fuel Line Connection
A licensed plumber connects the generator to your home's natural gas line or propane tank.
Electrical Connections
An electrician connects the transfer switch to your electrical panel and wires the generator to the transfer switch.
Inspections & Testing
Local inspectors verify code compliance, followed by comprehensive system testing.
Installation Requirements & Considerations
Location Requirements
- ✓Minimum 18" clearance from building walls
- ✓5' distance from doors, windows, and vents
- ✓Away from overhanging trees or structures
- ✓Level ground with proper drainage
Permit Considerations
- ✓Electrical permits for system wiring
- ✓Mechanical/plumbing permits for fuel connections
- ✓Zoning permits for placement & noise compliance
- ✓HOA approval (if applicable in your community)
Installation & Size Cost Considerations
| Cost Factor | Small System (8-14kW) | Medium System (16-22kW) | Large System (24kW+) |
|---|---|---|---|
| Generator Unit | $3,000-$4,500 | $4,500-$6,000 | $6,000-$12,000+ |
| Transfer Switch | $500-$1,000 | $1,000-$1,500 | $1,500-$2,000+ |
| Installation Labor | $1,500-$3,000 | $2,000-$3,500 | $3,000-$5,000+ |
| Annual Maintenance | $150-$250 | $200-$300 | $250-$400 |
*Prices vary by region, complexity of installation, and specific site requirements
Finding a Qualified Installer
The quality of installation directly impacts your generator's performance, reliability, and safety. Here's how to find the right professional:
Ready to Get Started?
Find qualified generator installers in your area who can provide personalized quotes and professional service.
