Whole House Generator Installation: Step by Step
Updated 28 March 2026
From permit application to first automatic startup, standby generator installation takes 3 to 6 weeks. The physical work takes 1 to 2 days once permits are approved. Here is what happens at every stage.
Full installation cost breakdown
| Component | Typical Cost |
|---|---|
| Generator unit (16 to 22kW) | $3,000 to $5,000 |
| Automatic transfer switch | $500 to $1,500 |
| Concrete pad | $300 to $800 |
| Gas line connection | $300 to $1,500 |
| Electrical labor | $500 to $1,500 |
| Permits | $100 to $300 |
| Total installed (16 to 22kW) | $7,000 to $15,000 |
Permits and utility notification
Standby generator installation requires permits in virtually all US jurisdictions. You typically need a building permit, an electrical permit for the transfer switch and panel work, and a gas permit for the fuel line connection. Some areas also require a mechanical permit. Permit fees total $100 to $300 in most jurisdictions. Your generator installer handles the permit applications, but the permitting timeline is not within their control. Most jurisdictions take 2 to 4 weeks to review and issue residential generator permits. Some expedited permit programs exist in states with high outage frequency (Florida, Texas, the Southeast). In addition to permits, your utility must be notified before a generator is connected, to ensure the transfer switch is correctly installed so the generator cannot back-feed power onto the utility grid, which is dangerous for utility workers. Notify your utility company as part of the permit process.
Site selection and concrete pad installation
The generator must be placed on a level, stable surface. Most standby generators sit on a concrete pad that is poured specifically for the installation. The pad dimensions match the generator footprint plus several inches of clearance around it. Concrete pad installation costs $300 to $600 for a standard residential generator. Some generators come with pre-formed composite pads that can be used instead of poured concrete, at lower cost but less longevity. Placement rules apply: the generator must be a minimum of 5 feet from any opening (door, window, or air intake), at least 5 feet from any propane or natural gas meter, and at least 18 inches from the home's exterior wall for most models. Check the manufacturer's specifications and local codes for exact clearances. The generator should be accessible for maintenance without requiring tools to reach it.
Automatic transfer switch installation
The automatic transfer switch (ATS) is the brain of the standby generator system. It monitors utility power continuously. When it detects an outage, it disconnects the home from the utility, starts the generator, waits for the generator to reach stable operating voltage and frequency, and then switches the home's electrical load to the generator. When utility power returns, the process reverses automatically. The ATS is installed by a licensed electrician between the utility meter and your main electrical panel, or as a sub-panel protecting specific circuits. Two main configurations exist: a whole-house transfer switch that handles the entire electrical panel (required for a generator large enough to power everything), and a load-management transfer switch that manages priority circuits. The ATS is included with most standby generators, but the installation labor of $500 to $1,000 is typically quoted separately by the electrician.
Fuel line connection
For a natural gas generator, a licensed plumber or gas line contractor runs a new gas line from the nearest branch of your home's gas supply to the generator location. The required pipe size depends on the generator's BTU demand and the distance from the supply. A 22kW generator running at full load consumes roughly 180 cubic feet of natural gas per hour, which requires a supply line sized to deliver that volume at adequate pressure. Most residential gas lines need to be upsized or run as a dedicated branch to meet this demand. The gas line cost is $300 to $800 for a short run of under 50 feet and $600 to $1,500 for longer runs. For propane generators, a 250 to 500-gallon propane tank is installed near the generator. Tank installation by the propane supplier costs $800 to $2,000 and may be included in a propane supply contract. The connection from the tank to the generator is a short run that costs $100 to $300.
Electrical wiring and panel connection
The electrical work includes: wiring from the generator to the ATS, connecting the ATS to the main panel, running a low-voltage control wire from the ATS to the generator (for the automatic start signal), and installing any load-shedding relays if the system uses load management rather than whole-house coverage. For whole-house systems, the main panel may need to be reconfigured or a new sub-panel installed. Conduit routing from the generator to the ATS location inside the home adds labor time, particularly if the run requires penetrating the foundation or routing through finished spaces. A straightforward installation with the generator near the electrical panel takes a half-day for the electrical work. A complex installation with a long conduit run can take a full day.
Startup, testing, and homeowner orientation
After all components are installed and inspections are passed, the installer performs a commissioning test. The generator is started, run up to operating temperature, loaded with a test load, and verified to transfer correctly from the ATS. The automatic exercise cycle is programmed (most standby generators run themselves for 20 minutes once a week to keep the battery charged and lubricate the engine). The installer shows you the key operational controls, explains how to check oil level and battery condition, and provides the first maintenance schedule. Most manufacturers require a first service at 20 to 30 hours of operation. Service intervals after that are typically every 100 to 200 hours or annually, whichever comes first. The installer also explains what to do during a prolonged outage: how to monitor fuel levels, how to manually transfer back to utility power if needed, and how to silence alarms.
What contractors should be involved
Generator dealer / installer
Manages the overall project, installs the generator unit, concrete pad, and typically coordinates subcontractors. Choose a factory-authorized dealer for warranty coverage.
Licensed electrician
Installs the automatic transfer switch, runs conduit and wiring, makes the panel connection. Must be licensed and pull electrical permits.
Licensed plumber or gas contractor
Runs the natural gas line from the house supply to the generator. Must be licensed and pull gas permits. For propane, the propane supplier handles tank installation.
Building department inspector
Inspects the electrical and gas work before the system can be energized. Schedule the inspection through the contractor; do not bypass it.