Home Generator Installation: What Size Do You Need?

Texas homeowners face severe weather year-round. Hurricanes hit the Gulf Coast. Ice storms strike up north. Power outages can last for days. In fact, Texas had 210 weather-related outages from 2000 to 2023, according to the Texas Tribune. That’s more than any other state. Many families now invest in home generator installation to keep the lights on. But choosing the right size is critical. An undersized unit won’t power your needs. An oversized unit wastes money and fuel. This guide explains home generator installation sizing so you can pick the perfect unit for your home.

Why Generator Size Matters

Choosing the correct size for your home generator installation is vital. Here’s why:

Undersized generators cause problems:

• They can’t power all your appliances
• Voltage drops lead to flickering lights
• Equipment may shut off unexpectedly
• The unit can overheat and break down
• Your generator’s lifespan gets cut short

Oversized generators waste resources:

• Higher upfront costs
• More fuel burned than needed
• Engines run at low load (bad for diesel units)
• Money wasted over time

A properly sized generator supplies reliable power without strain. It keeps your devices running safely during outages. It operates efficiently without waste. Home generator installation sizing is the foundation of a successful backup power system.

Home Generator Size Guide: How to Calculate Your Power Needs

Follow these steps to determine the right size for your home generator installation:

List Your Essential Appliances

Start by listing what you want to power during an outage:

• Refrigerator
• Lights
• Wi-Fi router
• Phone chargers
• Air conditioning
• Water heater
• Well pump
• Medical equipment

Be realistic about your must-have items. For whole home generator installation, include nearly everything. For portable units, focus on critical circuits only.

Find Running and Starting Watts

Check each appliance’s wattage. Look at labels or manuals for this info.

Common running wattages:

• Refrigerator: 600-800 watts
• Central AC: 2,000-4,000 watts
• LED lights: 10-20 watts each
• Wi-Fi router: 10-50 watts

Motor-driven appliances need extra power to start. Starting watts can be 2-3 times the running watts. For example:

• Central AC runs at 3,500 watts
• But needs 7,000 watts to start

If your generator can’t supply that surge, the appliance won’t start at all.

Add Up Total Wattage

Calculate your total running load. Add the single largest starting surge on top. Then add a 20-30% safety buffer.

Why the buffer matters:

• Prevents running at 100% capacity
• Improves fuel efficiency
• Allows for future appliance additions
• Gives headroom on hot Texas days

For example, if you need 15 kW, shop for an 18-20 kW unit.

Reference Typical Sizes

Use this home generator size guide for comparison:

Small homes or essential circuits only:

• 7-10 kW generators
• Powers fridge, lights, small AC

Medium to large homes:

• 20-22 kW generators
• Runs most appliances including central HVAC

Large luxury homes:

• 30-45 kW generators
• Powers multiple AC units and heavy loads

Most homes need 10-30 kW capacity. When in doubt, consult a licensed electrician for accurate load calculations.

Portable vs. Whole Home Generators

Your choice affects the home generator installation sizing you’ll need.

Portable Generators

These smaller units power essential items only.

Capacity: 3,000-7,500 watts Cost: $500-$2,500 Fuel: Gasoline or propane

Pros:

• Affordable upfront
• Flexible and movable
• Store until needed

Cons:

• Manual operation required
• Need frequent refueling (6-18 hours)
• Must run extension cords
• Noisy with exhaust fumes
• Outdoor placement required

Best for short outages and partial home backup.

Standby Generators (Whole Home)

A whole home generator installation provides seamless backup power.

Capacity: 10-30+ kW Cost: $7,000-$15,000 installed Fuel: Natural gas or propane

How they work:

• Permanently installed outside your home
• Connected to electrical panel via Automatic Transfer Switch (ATS)
• ATS detects outages in seconds
• Generator starts automatically
• Switches back when grid power returns
• No manual operation needed

Benefits:

• Powers entire home or large portions
• Runs indefinitely on home gas supply
• No refueling during multi-day outages
• Works even when you’re away
• Life continues normally during blackouts

The investment brings convenience and peace of mind. For families working from home or with vulnerable members, standby generators are worth it.

Installation Requirements

Home generator installation must be done correctly for safety and reliability.

Professional Installation Required

Don’t DIY this project. Standby generators need:

• Licensed electricians for wiring
• Plumbers for gas line connections
• Proper load calculations
• Transfer switch installation
• Code compliance verification

Improper installation risks equipment damage and safety hazards.

Permits and Codes

Expect to obtain permits for whole home generator installation. Requirements include:

• Electrical permit
• Plumbing permit (if gas line installed)
• City inspection upon completion
• National Electrical Code (NEC) compliance
• Proper unit placement and clearances
• Transfer switch to prevent backfeeding

Texas Senate Bill 1202 (effective Sept 1, 2025) requires faster permitting. The City of Alvin notes this helps homeowners get quicker approvals.

Site Preparation

Your generator needs:

• Outdoor placement on level concrete pad
• Adequate ventilation clearance
• Location above flood levels
• Proximity to electrical panel and fuel supply
• Distance from bedrooms to reduce noise

Professional installers handle site selection and preparation.

HOA Considerations

Texas Property Code §202.019 prevents HOAs from unreasonably blocking generator installation. They can’t forbid code-compliant units. Check your HOA’s aesthetic guidelines, but they must allow backup power systems.

Frequently Asked Questions

What size generator do I need for a 2,000 sq ft home?

Most 2,000 sq ft homes need 15-22 kW generators for whole-home backup. This covers central AC, appliances, and all circuits comfortably.

Can I install a generator myself?

No. Standby generators require licensed electricians and plumbers for safe, code-compliant installation. DIY installation risks safety and may void warranties.

How much does home generator installation cost?

Professional whole home generator installation typically costs $7,000-$15,000 total. This includes the generator unit plus installation labor and permits.

What’s better: natural gas or propane generators?

Natural gas generators connect to your home’s gas line for unlimited fuel. Propane requires tank refills but works anywhere.

How long can a standby generator run?

Standby generators on natural gas or propane can run indefinitely during outages. Portable units need refueling every 6-18 hours depending on load.

Do I need a permit for generator installation?

Yes. Most Texas cities require electrical and plumbing permits for standby generator installation. Your installer handles the permit process.

Stay Powered During Any Outage

Power outages in Texas can disrupt your life during extreme weather. A properly sized home generator installation provides reliable backup power when you need it most. Calculate your home’s wattage needs carefully. Choose between portable and whole-home options based on your budget and requirements. Always work with licensed professionals for installation.

Don’t wait for the next blackout to take action. The right generator keeps your family safe and comfortable through any storm.

Ready to protect your home with reliable backup power? LiveWire Electric TX offers professional home generator installation services throughout Texas. From sizing consultations to turnkey installation, we handle everything. Contact us today for a free quote and stay powered during the next outage!

Weatherford

Mineral Wells

Aledo

Palo Pinto

North TX Surrounding Areas