Generac Generator Installation: Process, Cost & Requirements

Step 1: Size the Generac Generator

Generator sizing comes before installation.

Do not choose the generator from house square footage alone.

The installer should determine which loads you want backed up and how much electrical demand those loads can create.

Important loads include:

• Air conditioners
• Heat pumps
• Electric heating
• Electric water heaters
• Well pumps
• Sump pumps
• Refrigerators
• Freezers
• Electric ranges
• Pool pumps
• Medical equipment
• EV chargers

Motor-driven equipment also has starting demand that can be much higher than its normal running load.

A properly designed system therefore considers both:

running load + starting load

before the generator is selected.

Calculate your generator size →

Step 2: Decide What You Want the Generator to Power

Not every Generac installation has to power every circuit simultaneously.

There are three common approaches.

Essential-Load Backup

Only selected circuits receive generator power.

Examples:

• Refrigerator
• Lighting
• Well pump
• Internet
• Selected outlets
• One HVAC system

This can reduce generator size and cost.

Managed Whole-Home Backup

A larger portion of the house is connected, but heavy loads are controlled so they do not all operate simultaneously.

This often provides a good compromise between convenience and generator size.

Broad Whole-Home Backup

The system is sized to support most or all important household loads with fewer restrictions.

This normally requires greater generator capacity and may increase both equipment and installation cost.

Step 3: Choose Natural Gas or Propane

Most residential Generac standby installations use either:

• Natural gas
• Liquid propane

Fuel choice affects installation design.

Natural-Gas Installation

A natural-gas installation may require:

• Gas-load calculation
• Correct pipe sizing
• Meter-capacity verification
• Pressure verification
• Regulator work
• Larger gas piping
• Utility involvement

Do not assume that because your house already has natural gas, the existing system can automatically support a standby generator.

Large generators can add substantial fuel demand.

Propane Installation

A propane installation may require:

• Storage tank
• Correct tank capacity
• Regulator
• Fuel piping
• Tank placement
• Delivery access

The required tank size depends on the generator, expected electrical load and desired outage runtime.

Step 4: Choose the Generator Location

Generator placement affects:

• Safety
• Code compliance
• Installation cost
• Noise
• Maintenance access
• Fuel-line length
• Electrical-run length

A good installation site should be stable, well drained and accessible for future service.

Generac installations also need appropriate clearance from structures, openings and other equipment.

Do not blindly copy a clearance number from another Generac model or an old installation diagram.

Use the installation instructions for the exact generator being installed and the requirements of the local authority having jurisdiction.

Generac also advises that standby systems must comply with applicable national, state and local electrical, fuel and building requirements.

Does a Generac Generator Need a Concrete Pad?

Not always.

Depending on the generator and installation requirements, a Generac standby generator may be installed on an approved:

• Composite base
• Concrete pad
• Prepared gravel or crushed-stone base

The installation surface needs to remain stable and level.

The exact foundation requirements should come from the installation instructions for the model being installed.

A larger concrete pad is not automatically better if the manufacturer-approved installation uses another foundation system.

Step 5: Install the Automatic Transfer Switch

The automatic transfer switch is one of the most important parts of a Generac standby system.

Its job is to transfer electrical loads between:

utility power ↔ generator power

without allowing the two sources to feed the house simultaneously.

During an outage:

1. Utility power fails.
2. The generator detects the outage.
3. The generator starts.
4. The transfer system disconnects the selected loads from utility power.
5. Generator power is supplied.
6. Utility power returns.
7. The system transfers the house back.
8. The generator completes its shutdown cycle.

Different installations use different transfer-switch configurations.

The correct setup depends on:

• Electrical service size
• Generator capacity
• Whole-home vs selected-load design
• Load management
• Existing electrical equipment

Read our automatic transfer switch guide →

Step 6: Install Load Management if Required

Load management allows a generator to support a house whose potential maximum demand exceeds what the generator can safely supply at once.

For example, a home may have:

• Two air conditioners
• Electric dryer
• Electric water heater
• Pool equipment

The generator may not need to run all of those simultaneously.

A load-management system can temporarily prevent a lower-priority device from operating while another large load is active.

This can sometimes allow a homeowner to buy a smaller generator without giving up broad household backup.

Before simply moving from a 22 kW-class generator to a larger model, ask whether proper load management would solve the actual problem more economically.

Step 7: Complete the Fuel Connection

The generator needs adequate fuel flow at the required pressure during operation.

That means the fuel system has to be designed for the generator's demand rather than simply connected to the nearest convenient pipe.

For natural gas, this may involve:

• Pipe sizing
• Meter capacity
• Regulator configuration
• Pressure testing

For propane:

• Tank sizing
• Regulator configuration
• Pipe sizing
• Pressure testing

Poor fuel delivery can create generator performance problems even when the generator itself is perfectly functional.

Fuel work should comply with applicable codes and the requirements for the specific Generac model.

Step 8: Permits and Inspection

Generator installations can require permits for:

• Electrical work
• Fuel work
• Building/site work

Requirements vary by jurisdiction.

Some areas may also have:

• HOA restrictions
• Noise requirements
• Property-line rules
• Flood-zone requirements
• Equipment-location rules

The contractor should establish who is responsible for permits before the work begins.

Do not assume permits are included merely because the quote says "complete installation."

Ask.

Step 9: Generator Activation and Commissioning

Installation is not complete when the generator is physically connected.

The system still needs to be commissioned.

This can include:

• Electrical checks
• Fuel-system checks
• Generator activation
• Controller configuration
• Exercise schedule
• Transfer-switch testing
• Load testing
• Simulated outage

A proper commissioning process verifies that the generator and transfer system behave correctly when utility power actually disappears.

Should the Installer Simulate a Power Outage?

Yes.

A completed standby-generator installation should be tested under conditions that verify the transfer sequence.

A simulated outage allows the installer to confirm that:

• The generator starts
• Transfer equipment operates
• Required circuits receive power
• Load management works
• Utility restoration is detected
• The system transfers back correctly

A generator that has only been started manually has not demonstrated that the full standby system works.

How Long Does Generac Installation Take?

The physical installation itself may be completed relatively quickly, but the complete project can take much longer.

The overall timeline can include:

• Quote appointment
• Engineering or load assessment
• Generator availability
• Permits
• Utility coordination
• Fuel-system work
• Site preparation
• Installation
• Inspection
• Commissioning

Generac currently notes that installation itself can take hours while the preparation process may take multiple weeks.

So distinguish between:

installation day

and

total project timeline.

They are not the same thing.

Can You Install a Generac Generator Yourself?

Some site preparation can potentially be completed by a capable homeowner, and Generac publishes installation information for its equipment.

But a permanent standby-generator installation can involve:

• High-voltage electrical work
• Automatic transfer equipment
• Natural gas
• Propane
• Permits
• Code requirements
• Manufacturer startup requirements

Generac currently says DIY installation is possible in some circumstances but strongly recommends certified professional installation because of the complexity, code requirements and correct system setup.

For most homeowners, this is not where I would try to save money.

A generator that costs thousands of dollars is being installed because you expect it to work during exactly the moment when the normal electrical system has failed.

The installation matters.

Do You Need an Authorized Generac Installer?

Not every portion of an installation necessarily needs to be performed by the same business.

A project can involve:

• Generac dealer
• Electrician
• Gas contractor
• Propane supplier
• General contractor

But you should know who is responsible for:

• Generator sizing
• Generator installation
• Transfer equipment
• Startup
• Warranty work
• Future service

Using an authorised Generac dealer can simplify manufacturer-specific installation, activation and future service.

Find Generac dealers and installers →

Generac Installation Requirements Checklist

Before accepting a quote, verify these items.

Generator

• Correct model
• Correct kW rating
• Correct fuel
• Fuel-specific output confirmed
• Warranty identified

Site

• Location selected
• Clearances verified
• Drainage considered
• Service access maintained
• Foundation included

Electrical

• Transfer switch specified
• Service rating confirmed
• Breaker/panel work included
• Load management specified
• Surge protection addressed if required

Fuel

• Gas or propane design confirmed
• Pipe sizing checked
• Meter or tank capacity checked
• Regulator requirements identified
• Fuel pressure testing included

Administrative

• Permits included
• Inspections included
• HOA requirements checked
• Utility work identified

Commissioning

• Generator activation
• Transfer test
• Simulated outage
• Exercise cycle configured
• Homeowner handover

Common Generac Installation Mistakes

Oversizing the Generator

Bigger is not automatically better.

Oversizing can increase:

• Equipment cost
• Fuel demand
• Installation cost

without producing meaningful additional value.

Sizing Only by Square Footage

Square footage does not tell you whether the property contains:

• Electric heating
• Multiple AC systems
• Well pumps
• Pool equipment
• Other heavy electrical loads

Size from load.

Ignoring Fuel Capacity

The generator may be electrically large enough while the existing gas system is not capable of supplying it.

Installing Too Far From Utilities

Longer electrical and fuel runs generally increase cost.

Generac itself notes that placing the unit closer to gas and electrical service can reduce installation cost.

Buying Equipment Before Getting an Installation Quote

A homeowner can buy a generator at an attractive retail price and then discover that:

• It is the wrong size
• The transfer switch is wrong
• Installation is unusually expensive
• Contractors charge more for customer-supplied equipment

Get the installation scope first.

Comparing Quotes by Price Alone

One quote may include:

• Permits
• Fuel work
• Transfer switch
• Load management
• Commissioning

while another excludes half of them.

Compare scope before price.

What Should Be Included in a Generac Installation Quote?

A useful written quote should identify:

• Exact generator model
• Generator price
• Transfer-switch model
• Electrical scope
• Fuel scope
• Foundation
• Trenching
• Load management
• Permits
• Inspections
• Startup
• Warranty
• Exclusions
• Total installed price

Generac says its typical home standby quote can include the generator, transfer switch, installation labour, electrical work, fuel connection requirements and necessary site preparation.

If something important is missing from the quote, ask whether it is:

included, excluded or unknown.

Generac Installation vs. Kohler Installation

The physical requirements of a Generac and comparable Kohler installation are often broadly similar:

• Generator
• Foundation
• Fuel
• Electrical connection
• Transfer equipment
• Permits
• Commissioning

The more meaningful difference may be the contractor.

Compare:

• Installed price
• Local dealer competence
• Warranty service
• Parts availability
• Maintenance support
• Generator specifications

Do not choose a generator brand independently from the local company expected to keep it operational.

Compare Generac vs. Kohler →

How to Compare Generac Installation Quotes

Get at least two complete proposals where practical.

Then compare them line by line.

Compare quotes with our generator quote tool →

Look for differences in:

• Generator model
• Generator capacity
• Fuel output
• Transfer switch
• Load management
• Electrical work
• Fuel work
• Trenching
• Permits
• Maintenance
• Warranty service

If two dealers recommend very different generator sizes, ask both to explain their load calculations.

The disagreement itself can reveal whether one proposal is unnecessarily oversized or the other is underestimating the requirement.

Get a Generac Installation Quote

Do not start by asking:

"What is your cheapest Generac?"

Start with:

"What system does my property actually require, and what is the complete installed price?"

Then compare the answer from more than one qualified contractor.

Find Generac installers near you →

Calculate your generator size →

Compare Generac models →

Compare generator quotes →