• Largest cities
• Local notes
• Models & pricing
• Which model
• FAQs
• Get a quote

Largest cities we serve in Cook County, IL

The table lists the twelve most populous municipalities that lie wholly or partly in Cook County. Populations are the April 1, 2020 U.S. Census counts taken from each municipality’s Wikipedia entry; Chicago was also cross-checked against the 2020 Census table in the Cook County entry. Distances are miles (straight-line) from the nearest GSHA office, which for nearly all of Cook County is Lake Bluff; two cities, Cicero and Berwyn, were not on our measured list, so their mileage is estimated from neighboring Oak Park (measured at 27.4 miles) and marked “approx.” Where a city extends into a neighboring county, the note says so.

Installing a KOHLER generator in Cook County, IL

Three gas utilities, and the meter check that comes first

Cook County has three natural-gas utilities. Nicor Gas serves most suburban communities; its own county-by-county service list names every suburb in our table and “Chicago (Annexed Areas),” and the company describes a territory of around 17,000 square miles serving 2.3 million customers in the northern third of Illinois. Inside the city itself, Peoples Gas states that it delivers natural gas to more than 898,000 customers in the city of Chicago. Along the lake, North Shore Gas serves nearly 166,000 customers in 54 communities between Winnetka and the Illinois-Wisconsin border, while Nicor’s list also names several of those same north-shore villages, so there the utility depends on the specific address, and we confirm it from your gas bill or meter tag before we size anything. Gas heats 82.2 percent of occupied homes in the county (2019-2023 American Community Survey; the category also includes bottled, tank and LP gas), so most houses already have a service line to tie into, and the real question is capacity. A 20RCA draws 281,000 BTU per hour at full load and a 26RCA 290,000, on top of the furnace, water heater and range already on the meter; if the existing meter and regulator cannot carry that total, the utility has to upgrade the meter before the generator can run. Our gas technicians run that load check at the estimate and coordinate any meter upgrade with Nicor, Peoples or North Shore Gas.

ComEd service and the automatic transfer switch

ComEd (Commonwealth Edison) is the primary electric provider in Chicago and much of northern Illinois; its territory runs from Iroquois County north to the Wisconsin border and from the Iowa border to the Indiana border, which takes in all of Cook County. The automatic transfer switch is installed between ComEd’s meter and your main panel: when utility power drops, the switch starts the generator and moves the house onto it, and when ComEd returns it transfers you back and shuts the generator down. For whole-house coverage on a 200-amp service we use a service-entrance-rated switch; where whole-house coverage is not needed we use a KOHLER RXT switch with load management or an RDT switch, both described on our transfer switches and accessories page. Because 27.9 percent of Cook County houses were first built in 1939 or earlier (2019-2023 ACS), our electricians look at the existing service, meter socket and panel before recommending a switch, since the switch has to match what is actually on the wall; if a panel change is needed we tell you at the estimate, not on install day.

Who issues the permit: the county or your village

Permits depend on where the property sits. Only about 2.4 percent of Cook County residents (126,114 people, on a 2010 Census basis) live in unincorporated areas, and roughly 56 percent of them are in Bremen, Lemont, Leyden, Northfield, Maine and Orland townships, according to the Civic Federation. For those addresses, and for Forest Preserve properties, the Cook County Department of Building and Zoning issues the permit: “Generator” is one of the permit types it accepts online, its e-permits page lists a $100 deposit, and the department enforces the 2014 Cook County Electrical Code, the 2014 Illinois Plumbing Code and, for drawings submitted after December 1, 2021, the 2021 International Residential Code and related codes with county amendments. The county’s generator permit sheet asks for a plat of survey sealed by an Illinois registered surveyor and not more than five years old, a site plan showing the unit’s distance from every lot line, a single-line diagram of the meter, main panel and transfer switch, cut sheets for the generator and switch, and letters of intent from an electrical contractor registered with the department and from a registered plumbing contractor; the department’s FAQ adds that all references to the National Electrical Code must be removed from drawings and that electrical inspections are scheduled by calling the township’s field inspector. The sheet dates from 2015 and lists a different deposit formula than the current e-permits page, so we confirm current fees with the department when we apply. Everyone else, which is the large majority of the county, deals with their own city or village building department; the county’s e-permits page states it cannot process permits for the City of Chicago or for properties inside incorporated suburbs. Either way, GSHA prepares the drawings, pulls the electrical and gas permits and meets the inspectors, and most installs take one to two days on site once the permit is issued.

Generator placement, wells and septic

Cook County has a large share of older houses and a majority of housing units in multi-unit buildings: 45.3 percent of housing units are single-family houses, 54.0 percent are in multi-unit buildings, 27.9 percent of houses date from 1939 or earlier and only 4.4 percent were built since 2010 (2019-2023 ACS). That shows up in generator placement. KOHLER’s air-cooled units can sit as close as 18 inches from the house under NFPA guidelines, but local codes apply, and the county’s permit sheet wants the distance from every lot line drawn on the site plan; where a side yard is tight, the steel-enclosed 10RESV and 12RESV (30.6 by 28 inches) fit where the 47-inch-long RCA models do not. Private wells and septic systems do exist in the county: the Cook County Department of Public Health reviews and approves private sewage disposal systems throughout Cook County except in incorporated Barrington Hills, Inverness, Palos Park and South Barrington, which have their own septic ordinances, and Building and Zoning requires CCDPH approval before construction projects involving wells and septic. The generator application itself asks whether the property is on well and septic or on water and sewer, and if you are on a well the pump goes on the generator’s load list and affects which model we recommend.

Combined sewers, basement backups and the sump pump

Flooding is the other local factor. The Metropolitan Water Reclamation District’s Cook County Flood Response Resource Guide (December 15, 2025) notes that the Chicago region’s flat landscape makes it prone to flooding, that many communities have combined sewer systems in which sewage and rainwater share the same pipes, and that basement backups happen when rainwater enters neighborhood sewers faster than it can flow through them; it lists a malfunctioning sump pump among the sources of water in a home and points out that most homeowner’s insurance policies do not cover flooding. Its municipality directory lists each community’s sewer type, and the entries we checked for cities in our table appear in the table notes above. A sump pump only protects the basement while it has power, so it is the first circuit we put on the transfer switch, and our 10RESV essentials package is sized to carry it.

KOHLER models and installed pricing

About “installed from” prices. Every KOHLER generator is a custom installation. The “installed from” price is our starting package for that model (generator, standard automatic transfer switch, standard gas and electrical connections, permit handling and start-up). Your final price depends on generator placement, gas line size and length, electrical panel condition and local permit fees, so we confirm it with a free on-site estimate before any work begins. KOHLER’s published MSRP for the generator alone runs from $3,946 (10RESV) to $7,546 (26RCA).

Which KOHLER model fits homes in Cook County

Which KOHLER model fits a Cook County home

Cook County’s generator market is mainly its single-family houses (45.3 percent of housing units), a large share of them built before 1939, with a 2020-2024 median owner-occupied value of $324,500 and 82.2 percent of occupied homes heated with gas. An older gas-heated house on a close-set lot usually needs the furnace, sump pump, refrigerator and lights covered first and the air conditioning second; larger and newer homes, and anything on a well, push toward the RCA line. All five models below run on natural gas or propane (field-convertible), use the same RDC2 controller with the KOHLER Energy Management app, are rated for 181 mph winds and carry KOHLER’s 5-year/2,000-hour limited warranty covering parts, labor and travel, with 7- and 10-year extended coverage available. KOHLER recommends the cold-weather kit where temperatures drop below 32 F, which applies to every Cook County install.

• KOHLER 10RESV (9 kW on natural gas), installed from $8,000: essentials only, meaning furnace, refrigerator, sump pump, well pump and lights. The steel 30.6 by 28 inch enclosure fits where a side yard is tight.
• KOHLER 12RESV (11 kW on natural gas), installed from $8,500: the same narrow-lot footprint with room for essential circuits plus one air conditioner through load management.
• KOHLER 14RCA (12 kW on natural gas), installed from $9,000: entry whole-house for small and mid-size homes; KOHLER rates it to start and run a 5-ton air conditioner.
• KOHLER 20RCA (18 kW on natural gas), installed from $10,500: whole-house for most 2,500 to 4,500 square foot homes with one central air conditioner, with 41 kVA of motor-starting capacity.
• KOHLER 26RCA (24 kW on natural gas), installed from $12,000: the largest air-cooled KOHLER, for large homes running two air conditioners on load management, a well pump, an electric range or an EV charger.

Full specifications are on each product page and on our KOHLER generator installation cost page; KOHLER MSRP for the generator alone runs from $3,946 (10RESV) to $7,546 (26RCA). After the install, our KOHLER service and maintenance team handles warranty registration and annual maintenance so the unit is ready for the next outage.

Cook County KOHLER FAQs

Do you install inside the city of Chicago, or only the suburbs?

Both. The Loop is 29.9 miles (straight-line) from our Lake Bluff office and the North Side about 23, so the city is well inside our standard 50-mile radius. Inside Chicago the gas utility is Peoples Gas (Nicor Gas’s list names some annexed areas), and the permit goes through the City of Chicago rather than Cook County; the county’s own e-permits page states it cannot process permits for properties in the city. We run the gas-load check and coordinate any meter upgrade with Peoples Gas, and we pull the city permit ourselves.

Do I need a permit for a generator in unincorporated Cook County?

Yes. The Cook County Department of Building and Zoning issues generator permits for unincorporated areas and Forest Preserve properties, accepts the application online with a deposit currently listed at $100 (we confirm the fee when we apply), and requires a sealed plat of survey, a site plan with lot-line distances, a single-line diagram, equipment cut sheets and letters of intent from registered electrical and plumbing contractors. GSHA prepares that package and pulls the permit; if your address is inside a city or village, we pull it from that municipality’s building department instead.

Which gas utility do you coordinate with in Cook County?

It depends on the address: Nicor Gas in most suburban communities, Peoples Gas inside the city of Chicago, and North Shore Gas in the north-shore suburbs between Winnetka and the Wisconsin border, where Nicor also serves some villages. We confirm the utility from your bill at the estimate, run the gas-load check, and arrange a meter upgrade with that utility if the existing meter cannot carry the generator’s demand.

Is Orland Park inside your service area?

Yes. Orland Park is 44.8 miles (straight-line) from our Lake Bluff office and Oak Lawn is 39.5, both inside our standard 50-mile radius; Tinley Park at 48.9 miles is the farthest southwest suburb on our measured list. Communities more than 50 miles from both offices are quoted case by case.

How much does a KOHLER generator cost installed in Cook County?

The 10RESV (9 kW on natural gas) is installed from $8,000, the 12RESV from $8,500, the 14RCA from $9,000, the 20RCA from $10,500 and the 26RCA (24 kW on natural gas) from $12,000. That starting package includes the generator, a standard automatic transfer switch, standard gas and electrical connections, permits and start-up; a utility gas meter upgrade, a longer gas or electrical run or a panel change would be priced in your free on-site estimate.

Other county pages: McHenry County · Boone County · DuPage County · Kane County · Will County · Lake County · full KOHLER service area

More: how installation works and what is included · service and maintenance · transfer switches and accessories · why KOHLER

Sources: Chicago (Wikipedia, 2020 Census infobox) · Cook County, Illinois (Wikipedia, 2020 Census places table) · Elgin, Illinois (Wikipedia) · Cicero, Illinois (Wikipedia) · Schaumburg, Illinois (Wikipedia) · Evanston, Illinois (Wikipedia) · Arlington Heights, Illinois (Wikipedia) · Palatine, Illinois (Wikipedia) · Skokie, Illinois (Wikipedia) · Des Plaines, Illinois (Wikipedia) · Orland Park, Illinois (Wikipedia) · Oak Lawn, Illinois (Wikipedia) · Berwyn, Illinois (Wikipedia) · Nicor Gas: Where We Are (county-by-county service area) · Nicor Gas (Wikipedia) · Peoples Gas: Service Area · North Shore Gas: About · Commonwealth Edison (Wikipedia) · Cook County Department of Building and Zoning · Cook County e-Permits · Cook County Generator Installation Permit Requirements (rev. 08/04/2015) · Cook County Building and Zoning FAQ (November 2020) · Cook County Building and Zoning Code Posting (2021 code adoption) · U.S. Census Bureau QuickFacts: Cook County, Illinois · U.S. Census Bureau ACS 2019-2023 Narrative Profile: Cook County, Illinois · Civic Federation: Unincorporated Areas of Cook County (December 9, 2014) · Cook County Department of Public Health: Septic Systems · MWRD Cook County Flood Response Resource Guide (12/15/2025). Distances are approximate miles from the nearest GSHA office.

About GSHA Services, LTD

GSHA Services, LTD is a licensed and insured electrical, heating, cooling, plumbing and generator contractor and an authorized KOHLER generator dealer (listed on KOHLER’s dealer site). Offices: 1257 Cobblestone Way, Suite A, Woodstock, IL 60098 and 11 N Skokie Hwy, Suite G18A, Lake Bluff, IL 60044. Phone (224) 220-3660. Email info@gshaservices.com. We sell, install, service and repair KOHLER home standby generators across the northern Chicago suburbs and southeastern Wisconsin. Contact us · All service areas · Financing

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