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The Full Process

How Standby Generator Installation Works

From sizing your home to flipping on backup power — here is everything you need to know before you talk to a dealer.

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Step by Step

The Installation Process

A standard whole-home generator installation takes 1–2 days and follows a predictable sequence.

1

Load Assessment and Sizing

The installer surveys your home's electrical panel and identifies the circuits you want to back up — HVAC, refrigerator, lighting, medical equipment, and so on. Based on total wattage, they recommend a generator size in kilowatts. Our free calculator gives you a solid estimate before any dealer visit so you can verify their recommendation independently.

2

Site Survey and Fuel Source

The installer determines where the generator will be placed — typically on a concrete pad beside the house, at least 18 inches from any opening and 5 feet from any propane/natural gas line. They also confirm your fuel source: natural gas (preferred), propane, or LP. Propane systems require a properly sized tank, usually 500–1,000 gallons for a whole-home unit.

3

Permits and Utility Coordination

Standby generator installation almost always requires a permit — electrical, mechanical, and sometimes gas. A reputable installer pulls all permits before work begins and schedules inspections. Some utilities also require notification or disconnection coordination for transfer switch installation. Never work with a contractor who skips permitting.

4

Transfer Switch Installation

The automatic transfer switch (ATS) is the critical component that detects a utility outage and switches your home to generator power — usually within 10–20 seconds. The ATS is wired between the utility meter and your main electrical panel. Whole-home coverage typically uses a 200-amp ATS; partial-home coverage may use a load-management center that protects specific circuits.

5

Generator Placement and Connection

The generator is set on its concrete pad, connected to the fuel source, and wired to the ATS. For natural gas systems, the gas company typically connects the meter tap. For propane, the tank is placed and filled by a propane supplier. The installer verifies all fuel connections, grounds the unit per code, and runs the interconnect wiring to the transfer switch.

6

Testing, Startup, and Walkthrough

The installer performs a full load test to confirm the generator handles your home's circuits. They then walk you through routine maintenance — checking oil level, air filter, and coolant — and explain the weekly self-test cycle. Generac and Kohler units run a brief automatic exercise test every seven days to keep the engine lubricated and the battery charged. Your installer registers the unit under warranty before they leave.

Brand Comparison

Generac vs. Kohler

Both are excellent choices. Here is how they differ.

Generac

7–24 kW residential range
+Largest residential dealer network in the US
+Parts widely available, faster service
+Mobile Link remote monitoring app included
+Generally lower installed cost for same kW
-Slightly louder than comparable Kohler units

Kohler

12–38 kW residential range
+Quieter operation — better for HOA areas
+Stronger for larger homes and commercial use
+Reputation for durability and long service life
+OnCue remote monitoring included
-Fewer dealers in some regions; higher installed cost
Common Questions

Frequently Asked Questions

Most residential standby generator installations take one to two days for the electrical and mechanical work. If a new concrete pad is needed, allow another day for cure time. Gas line work may add a day depending on your local utility's schedule. Total time from signed contract to energized unit is typically 2–4 weeks, accounting for permit processing.
Yes, in virtually every jurisdiction. A properly installed standby generator requires at minimum an electrical permit, and usually a mechanical and gas permit as well. Any licensed installer should pull these on your behalf — if they suggest skipping permits, that is a red flag. Unpermitted installations can void your homeowner's insurance and create problems when you sell the property.
Most residential standby generators run on natural gas or propane (LP). Natural gas is preferred where available because it connects directly to your utility line — no tank to fill or worry about running empty. Propane works well in rural areas without gas service; a 500–1,000 gallon tank gives several days of continuous runtime under load. Diesel is common for commercial standby but rare in residential applications.
Installed cost typically ranges from $5,500 for an entry-level 11 kW unit up to $22,000 or more for a 48 kW whole-estate system. Most average single-family homes fall in the $7,500–$12,000 range for a properly sized 18–22 kW generator including the automatic transfer switch, concrete pad, and labor. Use our free calculator to get a more precise estimate for your specific home and loads.
The automatic transfer switch (ATS) continuously monitors incoming utility voltage. When it detects a loss of power — typically within 1–2 seconds — it signals the generator to start. After a 10–15 second warm-up period, the ATS disconnects the utility line and connects your home to generator power. When utility power returns and stabilizes, the ATS switches back and the generator cools down for a few minutes before shutting off.
Standby generators run a brief automatic self-test exercise weekly — usually Sunday morning at a pre-set time. Beyond that, annual professional maintenance is standard: oil and filter change, air filter inspection, spark plugs, coolant check, and battery test. Most manufacturers recommend the first service at 25 hours of runtime or 1 year, whichever comes first. Your installing dealer typically offers annual service contracts.

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