generator installation guide — what to expect and what it costs

You've picked your generator. You've sized it correctly. Maybe you've even found a deal on a 22kW Generac that showed up on sale at exactly the right moment. Now comes the part that nobody talks about until you're already committed: the installation.

And the installation is where the real money lives.

The generator itself might cost $5,000-7,000. The installation adds another $3,000-5,000 on top of that. I've seen people budget for the unit and completely forget about the concrete pad, the gas line, the transfer switch, the electrician, and the permits. Then they stare at the final invoice wondering how a $5,000 generator turned into a $12,000 project.

I'm going to walk you through the entire process so you know exactly what's coming, what it costs, what you can handle yourself, and what absolutely requires a licensed professional. No surprises.

the installation process, step by step

Every installation follows roughly the same sequence. Some installers compress it into a single day. Others spread it across a week or more, depending on their schedule and whether they're subcontracting the gas work. Here's what happens and why each step matters.

step 1: the site survey

Before anyone orders anything or pours anything, a qualified installer comes to your property and looks at four things:

• Generator placement. Where the unit can physically go, given setback requirements, terrain, access for maintenance, and proximity to your electrical panel and fuel source.
• Fuel source. Whether you're connecting to an existing natural gas line or propane tank, or whether a new fuel source needs to be installed. The distance from fuel to generator determines the complexity and cost of the gas line.
• Electrical panel. The condition and capacity of your main panel, whether it can accommodate a transfer switch, and whether any upgrades are needed. Older panels with Federal Pacific or Zinsco breakers will likely need replacement — which is expensive but necessary for safety regardless of the generator.
• Local code requirements. Setback distances, noise ordinances, permit requirements, and any HOA restrictions that affect placement or installation.

A good installer spends 30-60 minutes on the site survey. They measure things. They look at your panel. They check the gas meter's capacity. They ask about your priorities and explain options.

step 2: permits

Almost every jurisdiction in the country requires permits for a standby generator installation. You'll typically need:

• Electrical permit — for the transfer switch, wiring, and generator connection. Required virtually everywhere.
• Plumbing/gas permit — for the gas line. Required in most areas where gas work is involved.
• Building permit — some jurisdictions require this for the concrete pad or for any permanent outdoor equipment installation.

Your installer should pull these permits. That's part of what you're paying them for. Permit costs vary wildly by location — anywhere from $50 to $500 total. The timeline also varies. Some towns issue permits in 24 hours. Others take 2 weeks. This is often the bottleneck in the installation timeline.

After the installation, the municipality sends an inspector to verify the work meets code. This inspection is a good thing. It protects you. A licensed, competent installer will have zero concerns about passing inspection.

step 3: the concrete pad

Your generator needs a level, stable surface. There are two options:

• Poured concrete pad. A 3-4 inch thick concrete slab, typically 3x4 feet or sized to your specific unit. Costs $200-500 for materials and labor. Takes a day to pour and needs to cure for 24-48 hours before the generator goes on it.
• Composite generator pad. A prefabricated plastic/composite pad (GenPad is the common brand). Costs $150-300. Installs in minutes on a level gravel base. No curing time. Most installers now prefer these because they don't crack, they don't settle unevenly, and they get the job done faster.

The site needs to be level. If it isn't, expect additional grading or site preparation costs of $200-500. If the best placement spot is on a slope, retaining work or a raised pad can add more.

step 4: the gas line

This is where a licensed plumber or gas fitter earns their money. The gas line connects your generator to either your natural gas meter or propane tank. It sounds simple. It isn't.

The line must be sized correctly. Generators are hungry — a 22kW unit running at full load consumes roughly 220 cubic feet of natural gas per hour (about 240,000 BTU). The gas line needs enough diameter and pressure to deliver that volume without causing a pressure drop that affects your other gas appliances (furnace, water heater, stove).

Here's what matters:

• Distance from the meter or tank. Longer runs need larger diameter pipe or higher pressure. A 20-foot run from the meter is straightforward. A 100-foot run to the other side of the house is a different project entirely.
• Existing meter capacity. Your gas meter has a maximum flow rate. Adding a generator may exceed it. If so, the gas utility needs to upgrade your meter — which is usually free but takes time to schedule.
• Pipe material. Black iron pipe is traditional and reliable. CSST (corrugated stainless steel tubing) is faster to install and often cheaper. Both are code-compliant when installed correctly. CSST must be properly bonded to the home's electrical grounding system.
• Propane considerations. If you're on propane, you need a tank large enough to run the generator for your target duration. A 22kW generator burns roughly 3-4 gallons of propane per hour at full load. A 500-gallon tank (filled to the standard 80%, so 400 usable gallons) gives you about 100-130 hours at full load. A 250-gallon tank gives you roughly half that.

Gas line installation typically costs $500-1,500 depending on distance, complexity, and your region's labor rates. If the gas utility needs to upgrade your meter, add 1-3 weeks to the timeline.

step 5: electrical work and the transfer switch

This is the most critical part of the installation and the most expensive. It's also the part that absolutely, unequivocally requires a licensed electrician.

The electrician does three things:

1. Installs the automatic transfer switch (ATS). The ATS mounts next to or near your main electrical panel. It monitors utility power, detects an outage, signals the generator to start, waits for the generator to stabilize (usually 10-30 seconds), and then transfers your home's circuits from utility power to generator power. When utility power returns, it transfers back and shuts down the generator. All automatic. No human intervention required. For a deeper look at how transfer switches work and which type you need, I wrote a complete transfer switch guide.
2. Connects the generator to the transfer switch. This involves running electrical conduit and wiring from the generator's output terminals to the transfer switch. The wire gauge and conduit size depend on the generator's output capacity and the distance between the two.
3. Configures load priorities. If you have a load-shedding transfer switch (common on 16-22kW installations), the electrician assigns circuits to managed and unmanaged loads. Critical circuits like the refrigerator and well pump get priority. Lower-priority circuits like the AC and electric dryer get managed — meaning the switch can temporarily shed them during high-demand periods.

The transfer switch itself costs $500-1,200 depending on amperage rating and features. Labor for the electrical work runs $1,000-2,000. Total electrical costs: $1,500-3,000.

step 6: startup and commissioning

The generator is on the pad. The gas line is connected. The transfer switch is wired. Now the installer brings it to life.

Commissioning involves:

• Verifying gas pressure at the generator inlet.
• Programming the generator's controller — setting exercise schedule, voltage regulation, and transfer delay parameters.
• Running the generator under no-load conditions to check for leaks, unusual noise, or error codes.
• Simulating a power outage by shutting off the main breaker and verifying the entire automatic transfer sequence works correctly.
• Load testing — running the generator while major circuits are active to verify voltage stability and that the transfer switch handles load transitions properly.
• Walking you through basic operation, the weekly exercise cycle, maintenance schedule, and how to shut it down manually in an emergency.

This takes 1-2 hours when everything goes smoothly. A thorough installer won't rush it.

timeline: how long the whole thing takes

Here's a realistic timeline from "I want a generator" to "my generator runs automatically when the power goes out":

Best case: 1 week from first phone call to running generator. This happens when the equipment is in stock locally, your permit office is fast, and the installer has availability.

Typical case: 2-4 weeks. This is what I'd plan for. Equipment usually ships within a week, permits take a few days, and installers are booked out at least a week.

Worst case: 8-12 weeks. This happens after a major storm when everyone in your area wants a generator at the same time. Equipment backlogs, installer schedules packed solid, permit offices overwhelmed. If you're reading this before hurricane season, take the hint.

cost breakdown: where the money goes

Here's the real cost picture for a typical 20-22kW standby generator installation. These are 2025-2026 numbers for a standard residential installation. Your region may be higher or lower.

The wide range reflects real variation. A straightforward installation — generator near the panel, short gas line run, level site, no panel upgrade — comes in around $8,000-10,000 total. A complex installation — generator far from the panel, long gas run, panel upgrade, difficult terrain — can hit $15,000 or more.

For a complete breakdown of what drives these costs up or down, see my whole-house generator cost guide.

what you can DIY vs. what requires a pro

I'm a big believer in doing your own work where it makes sense. I'm also a big believer in not dying. Here's where the line falls for generator installation.

things you can do yourself

• Site preparation. Clearing brush, leveling the ground, laying a gravel base. Shovel and rake territory.
• Pouring the concrete pad or placing a composite pad. Basic concrete work. If you've done a small patio or fence post, same skill level.
• Trenching for conduit or gas line. Digging a trench from the generator location to the house. Call 811 before you dig to have utilities marked. Sweat equity that saves $200-400.
• Researching and purchasing the generator. Don't let the installer mark up the equipment. Buy the generator yourself from a major retailer or authorized dealer and have it delivered. Some installers add 15-30% markup on the unit itself.

things that require a licensed professional

• Electrical work — all of it. Transfer switch installation, generator wiring, panel connections. A licensed electrician. No exceptions. This is not a "watch a YouTube video and wing it" situation. Incorrect electrical connections can back-feed power into utility lines, which can kill the lineworker trying to restore your power. It can also start a fire in your panel. Don't do it.
• Gas line work. Running, sizing, and connecting the gas line. A licensed plumber or gas fitter. Gas leaks cause explosions. The consequences of a bad connection are catastrophic and irreversible.
• Final commissioning. The startup, testing, and configuration should be done by someone who knows the specific generator model. Most manufacturers require professional commissioning to activate the warranty.

code requirements and setback distances

Generator installations are governed by a mix of national codes and local amendments. The major codes that apply:

• National Electrical Code (NEC/NFPA 70) — governs the transfer switch installation, wiring methods, grounding, and the connection between generator and panel.
• National Fuel Gas Code (NFPA 54) — governs gas line sizing, materials, installation methods, and connections.
• Local building codes — can add requirements on top of the national codes. Some jurisdictions are stricter. Always check local before assuming the national code is all you need.

setback distances

This is where placement gets specific. The standard setback requirements per NFPA 37 and most local codes:

• 5 feet from any operable window, door, or fresh air intake. This prevents exhaust from entering the home. Carbon monoxide from a generator will kill you and your family. This setback is non-negotiable.
• 18 inches from the building wall. This provides ventilation space and access for maintenance. Some manufacturers require 36 inches or more — check your specific generator's installation manual.
• 5 feet from any combustible material. Fences, decks, wood piles, landscaping that could catch fire.
• Clearances from property lines. Varies by jurisdiction. Typically 3-5 feet minimum, sometimes more in dense residential areas.
• Distance from HVAC equipment. Most codes require 3-5 feet separation from outdoor AC condensers, heat pump units, and other mechanical equipment.

These setbacks can create real constraints on smaller lots. I've seen situations where the only code-compliant location is the opposite side of the house from the electrical panel, which means longer wire runs and higher installation costs.

noise ordinances

Modern standby generators produce 60-70 decibels at rated load — roughly the volume of a normal conversation. Older or larger units can be louder. Most residential noise ordinances set limits between 55-75 dB at the property line.

Things that affect noise levels:

• Distance from neighbors. Sound drops about 6 dB every time you double the distance from the source. Moving the generator from 20 feet to 40 feet from the property line cuts perceived loudness nearly in half.
• Enclosure quality. Factory enclosures on generators like Generac Guardian and Kohler units are engineered for noise reduction. Aftermarket enclosures or sound barriers can help with older or louder units.
• Load level. Generators are louder under heavy load. A generator running at 50% capacity is noticeably quieter than the same unit at full load.
• Weekly exercise cycle. Your generator runs a 15-20 minute exercise cycle weekly to keep the engine and electrical components healthy. Some jurisdictions have time-of-day restrictions on when this can occur. Set it for a weekday afternoon, not Saturday at 7 AM. Your neighbors will thank you.

how to find and vet installers

The quality of your installation depends entirely on who does the work. A great generator installed badly is worse than a mediocre generator installed properly. Here's how to find the right person.

where to look

• Manufacturer dealer locators. Generac, Kohler, and Briggs & Stratton all have authorized dealer networks. These installers have been factory-trained on specific equipment. Start here.
• Electrical contractors with generator experience. Not all electricians install generators regularly. You want someone who does this frequently, not someone figuring it out on your dime.
• Word of mouth. Ask neighbors who have standby generators. Ask on local community forums and neighborhood apps. Firsthand experience from someone in your area is worth more than any online review.

what to ask

• How many generator installations have you done in the last 12 months? (You want at least 10-20. More is better.)
• Are you factory-authorized for the brand I'm installing?
• Do you pull all permits and handle the inspection?
• Who does the gas line — you or a subcontractor? (Either is fine, but you want to know.)
• What does your quote include, specifically? (Get it in writing.)
• What's your warranty on the installation labor?
• Can I talk to two or three recent customers?

red flags in contractor quotes

I've collected quotes from seven different installers over the years. Here's what tells me to keep looking:

• No site survey. A quote generated from a phone call or online form, without anyone visiting your property. Meaningless number. Guaranteed change orders.
• No line-item breakdown. A single lump-sum number with no breakdown of equipment, labor, materials, and permits. You have no way to evaluate what you're paying for or compare quotes.
• Significantly below market rate. If three quotes come in at $10,000-12,000 and one comes in at $6,000, that installer is either cutting corners, skipping permits, or planning to hit you with change orders. The cheapest quote is almost never the cheapest installation.
• "We don't need permits for this." Yes, you do. Everywhere. An installer who tells you otherwise is either ignorant or dishonest. Either way, not someone you want wiring your house.
• Pressure to sign immediately. "This price is only good today." That's a sales tactic, not a business practice. Any legitimate installer will hold a quote for 30 days minimum.
• No mention of the transfer switch. If the quote includes the generator and "installation" but doesn't specifically call out the transfer switch, ask. The transfer switch is the most important component after the generator itself. I explain why in the transfer switch guide.
• Won't provide references or proof of license. Licensed contractors are proud of their credentials. If someone hesitates to show you their license or connect you with past customers, that's your answer.

the bottom line

A whole-house generator installation is not a weekend project. It's a significant investment that involves multiple licensed trades, permits, inspections, and careful planning. The installation costs roughly as much as the generator itself, and trying to cut corners on the installation is one of the worst decisions you can make.

But here's what you get for that money: a system that starts itself within seconds of a power outage, runs your entire house (or your critical loads) without any intervention from you, and keeps running for as long as it has fuel. No extension cords. No going outside in the storm. No worrying about what's happening at home while you're at work.

If you haven't sized your generator yet, start with the sizing calculator. If you need help choosing between units, the best whole-home generator review has my current recommendations. And if the price of a standby installation is out of reach right now, that's okay — a portable generator with a manual transfer switch gets you 80% of the benefit at 20% of the cost.

Whatever you do, don't wait until the lights go out to start this process.