How standby generator installation works, step by step

A whole-home standby generator is one of the bigger electrical projects a homeowner takes on, and it involves more coordination than most people expect: an electrician, sometimes a gas line contractor, a permit, and a utility inspection all have to line up. Here’s the sequence.

Step 1: sizing the generator to your home

Before anything gets installed, an electrician calculates your home’s actual load. This depends on square footage and, more importantly, what you want covered during an outage: just essential circuits like the fridge, sump pump, and a few lights, most of the home, or everything including central air. A generator sized for essentials only is a fraction of the cost of one sized to run a whole home with HVAC.

Step 2: site placement and gas line assessment

The generator unit sits outside on a concrete pad, typically near the gas meter and electrical service, with required clearances from windows, doors, and property lines per local code. If you don’t already have gas service sized for the generator, this is where a gas line contractor gets looped in, since most standby units run on natural gas or propane rather than gasoline.

Step 3: permitting

Standby generator installation requires an electrical permit, and often a separate gas permit if new gas line work is involved. This step happens before installation and can take several days to process, so it’s worth starting early if you’re targeting a specific timeline, like before storm season.

Step 4: the electrical and mechanical installation

This is the multi-part work: setting the pad and unit, running the gas line, wiring the generator to your panel, and installing an automatic transfer switch. The transfer switch is what makes the whole system work safely. It disconnects your home from utility power the moment an outage is detected, connects you to the generator, and switches back automatically once utility power is restored. This prevents backfeeding power into utility lines, which is both a code violation and a real danger to utility workers.

Stage	What’s involved	Who’s typically on-site
Sizing	Load calculation based on home size and coverage needs	Electrician
Gas line (if needed)	New or upsized gas line to the unit	Gas contractor, sometimes coordinated by the electrician
Pad and unit placement	Concrete pad, clearances from structures	Electrician or installation crew
Wiring and transfer switch	Panel connection, automatic transfer switch install	Licensed electrician
Inspection	Utility and code inspection before activation	County/city inspector, utility representative

Step 5: testing and inspection

Once installed, the electrician tests the transfer switch and runs the generator through a simulated outage to confirm it powers the intended circuits. A local inspector reviews the installation for code compliance, and depending on your utility, a representative may also need to inspect the connection point before the system is cleared for full use.

What determines your timeline

Homeowners often underestimate how much the gas line and permit steps add to the calendar versus the actual installation day. If you’re planning ahead of a specific season, start the sizing and permitting process a month or more out. Reviewers of local generator installers consistently mention electricians who manage the full process, permits, inspections, and gas coordination included, as the ones worth the higher price over a company that only handles the wiring.

Once it’s installed, don’t forget the maintenance

A standby generator that’s installed correctly still needs periodic servicing to work when you actually need it. Most units run a short self-test automatically on a schedule, cycling the engine briefly to confirm it starts. Beyond that automatic check, plan on an annual service visit to change oil and filters and confirm the whole system, including the transfer switch, is functioning. A generator that’s sat unused between outages is the most common source of failure right when it matters most, so treat servicing as part of the ownership cost, not an optional extra.

If you want a rough sense of what size generator your home needs, this directory has a free sizing calculator on its tools page that factors in square footage, HVAC, and how much of the home you want covered. To compare local installers, see the generator installation category, and check the methodology behind how providers are scored. Start browsing from the home page if you’re weighing generator installation against other electrical priorities.