Standby Generator Size Calculator
Calculate the appropriate size for your whole house standby generator by entering your home's electrical loads below.
House Information
Essential Systems
Additional Appliances
Add Custom Loads
Added Custom Loads
List of the Top 10 Best Standby Generator:
About Standby Generator Sizing
Proper sizing of a standby generator is crucial for reliable whole-house backup power. Our calculator helps you determine the right size based on your specific needs and electrical loads.
Types of Standby Generators
| Generator Size | Coverage | Best For |
|---|---|---|
| 12-16 kW | Partial House | Essential circuits, small homes |
| 20-24 kW | Whole House (Medium) | Average homes up to 3000 sq ft |
| 25-35 kW | Whole House (Large) | Larger homes with multiple HVAC units |
| 38-48 kW | Estate/Commercial | Luxury homes, small businesses |
Typical Power Requirements for Home Systems
| System/Appliance | Running Watts | Starting Watts |
|---|---|---|
| Central AC (3 Ton) | 5,000W | 12,500W |
| Electric Water Heater | 4,500W | 4,500W |
| Electric Range | 8,000W | 8,000W |
| Well Pump (1 HP) | 2,100W | 6,300W |
| Electric Dryer | 5,400W | 5,400W |
Key Considerations for Standby Generator Installation
1. Local Codes and Permits
Before installing a standby generator, consider:
- Building permits required by your municipality
- Electrical codes and inspections
- Zoning restrictions and setback requirements
- Noise ordinances that may affect placement
- HOA regulations and approval requirements
2. Installation Requirements
Key installation factors include:
- Professional installation by licensed electricians
- Automatic transfer switch installation
- Proper foundation and mounting
- Safe distances from buildings and property lines
- Adequate ventilation and airflow
3. Fuel Source Options
| Fuel Type | Advantages | Considerations |
|---|---|---|
| Natural Gas | Continuous supply, clean burning | Requires gas line, dependent on utility |
| Liquid Propane | Clean burning, long shelf life | Requires tank installation, regular refills |
| Diesel | Efficient, long running time | Fuel storage, maintenance needs |
Maintenance Requirements
Regular Maintenance Schedule
- Monthly Tasks:
- Exercise generator for 20-30 minutes
- Check oil level and condition
- Inspect air intake and cooling slots
- Verify proper operation of transfer switch
- Semi-Annual Tasks:
- Change oil and filter
- Check battery condition
- Clean or replace air filter
- Inspect fuel system components
- Annual Service:
- Professional inspection and tune-up
- Spark plug replacement
- Fuel system cleaning
- Transfer switch testing and maintenance
Frequently Asked Questions
How long do standby generators last?
With proper maintenance, a standby generator can last:
- 15-20 years for residential use
- 10-15 years for commercial applications
- Factors affecting lifespan include:
- Frequency of use
- Maintenance quality
- Environmental conditions
- Load management
What is an automatic transfer switch?
An automatic transfer switch (ATS) is a crucial component that:
- Monitors utility power continuously
- Automatically starts generator during outages
- Safely switches home's electrical load
- Prevents back-feeding into utility lines
- Returns to utility power when restored
How much does installation cost?
Installation costs typically include:
- Basic Components:
- Generator unit: $3,000-$15,000
- Transfer switch: $500-$1,500
- Installation labor: $2,000-$5,000
- Additional Costs:
- Permits and inspections
- Site preparation
- Fuel system installation
- Electrical upgrades if needed
What size transfer switch do I need?
Transfer switch sizing depends on:
- Home's electrical service size (100A, 200A, etc.)
- Generator capacity
- Critical circuit requirements
- Whole house vs. partial coverage
How often should the generator exercise?
Recommended exercise schedule:
- Weekly exercise for 20-30 minutes
- Run under load when possible
- Vary exercise time to avoid predictable grid strain
- Consider seasonal adjustments
Safety Considerations
Carbon Monoxide Safety
- Proper placement away from windows and doors
- Installation of CO detectors
- Regular exhaust system inspection
- Adequate ventilation maintenance
Electrical Safety
- Professional installation and maintenance
- Regular transfer switch testing
- Proper grounding system
- Circuit protection verification
Fuel Safety
- Regular fuel system inspection
- Proper fuel storage practices
- Leak detection systems
- Emergency shut-off procedures
Environmental Impact
Consider these environmental factors:
- Emissions:
- EPA compliance requirements
- CARB certification in California
- Clean fuel options
- Noise Pollution:
- Sound level ratings
- Sound attenuation options
- Placement considerations
- Efficiency Measures:
- Load management systems
- Smart technology integration
- Maintenance optimization