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

Largest cities we serve in DuPage County, IL

The table lists the twelve largest municipalities that lie wholly or partly in DuPage County, ranked by 2020 U.S. Census population. Several of them straddle a county line (the notes say which); we serve the whole municipality, not just the DuPage portion. Mileage is the driving distance by road from the nearer of our two offices to the city center, rounded to the nearest mile, and the office column names that office. Every city here is inside our standard 50-mile service radius, which is measured as the crow flies from each office; two of them, Naperville and Bolingbrook, are inside the radius but more than 50 miles by road from both offices, and their notes say so.

Installing a KOHLER generator in DuPage County, IL

Natural gas: Nicor Gas and the gas-load check

Nicor Gas (Northern Illinois Gas Company) is the natural-gas utility we expect to meet across DuPage County: the City of Wheaton names it as the gas provider for Wheaton residents, the Village of Woodridge lists it as its natural-gas provider, it is headquartered in Naperville, and according to Wikipedia it serves more than two million customers across most of the northern third of Illinois outside the city of Chicago. Nicor’s own service-area page is a ZIP-code lookup rather than a county list, so if you are unsure whether it serves your address, check your ZIP there. For a generator this matters because a KOHLER air-cooled unit draws a lot of gas at full load, from 179,000 BTU/hr for the 10RESV to 290,000 BTU/hr for the 26RCA, on top of your furnace, water heater and range. Our gas-line technicians run a load check on the existing meter and piping before we quote; when the meter cannot carry the added demand, a meter upgrade by the utility is sometimes needed, and we tell you at the estimate whether your home is likely to need one.

Electric service: ComEd, the Naperville exception and the transfer switch

Commonwealth Edison (ComEd) is the electric provider named on the Wheaton and Woodridge utility pages, with one large exception: the City of Naperville owns and operates its own municipal electric utility, with its own outage-reporting line at (630) 420-6060. Storm outages do reach the county. On June 10, 2026, NBC Chicago reported more than 230,540 ComEd customers without power across the Chicago area as of 4:20 p.m., including two large outages of roughly 1,500 customers each in LaSalle and DuPage counties. Whichever utility feeds your home, the generator connects through an automatic transfer switch. Naperville’s generator-safety page spells out why: a suitable transfer switch disconnects your loads from the utility grid and prevents feedback of power through the generator when regular service is restored. Every GSHA starting package includes a standard automatic transfer switch; depending on the model and the loads we install KOHLER’s RXT switch (with load management) or RDT switch, and a service-entrance-rated switch for whole-house 200 A services.

Permits: DuPage County for unincorporated homes, your city or village otherwise

The county’s regional planning FAQ counts 39 municipalities wholly or partly within DuPage County, and where your home sits decides who issues the permit. For homes in unincorporated DuPage County, it is the DuPage County Building & Zoning Department, Building Division, 421 N. County Farm Road, Wheaton, IL 60187 (630-407-6700), which lists generators among its Residential Accessory permits and takes applications through its Accela Citizen Access portal. The county’s Permits and Forms page is blunt that “Work shall not commence prior to issuance of permit,” and every general and sub-contractor working in unincorporated DuPage must be registered with the DuPage County Building Official before the permit is issued, with registrations valid for one year. Inspections there are made against the 2020 National Electrical Code and the 2021 International Building, Fire, Mechanical, Fuel Gas and Property Maintenance Codes, plus the current Illinois Energy Conservation, State Plumbing and Accessibility Codes; the county’s updated building code took effect January 1, 2024. Inside a city or village, that municipality issues the permit and sets its own placement rules. Wheaton, the county seat, requires a plat of survey drawn to scale showing the proposed generator, the product installation specifications (including the fuel tank and transfer switch) and wiring and piping diagrams; it bars the unit from the required front or corner side yard, requires screening when the unit sits in a side yard adjacent to a street, keeps it at least 10 feet from building air-intake openings unless the intake is 3 feet below the source, and exempts generator sound during a natural-disaster outage and during weekly testing. Naperville requires an issued building permit before any construction begins and requires that standby generators be installed by electricians licensed by the City of Naperville; the city lists the cost at $85 ($40 for the permit and $45 for the inspection). That licensing requirement is set by the city, so mention it when you book a Naperville estimate and we will go over how it applies to your job before any permit is pulled. GSHA pulls the electrical and gas permits and schedules the inspections whichever authority applies, and once the permit is issued most installations take one to two days on site.

Wells and septic systems

Not every DuPage home is on municipal water and sewer. The DuPage County Health Department issues permits for installing or repairing a private water well and for installing or repairing a septic system, both through its Plan Review office at 630-221-7045, and the county’s Permits and Forms page notes that properties on wells or septics need Health Department review. The Health Department does not publish how many homes this covers, but if yours is one of them the sizing rule is simple: a well pump stops when the power does, so the well pump belongs on the generator’s covered circuits, which affects both the model and the transfer switch we recommend. Where a generator pad or gas trench would cross a septic field, we work out placement at the estimate so the county’s Health Department review is not a surprise.

Flooding and the sump pump

Stormwater is a long-running issue in the county. DuPage County Stormwater Management runs a Voluntary Buyout Program for homes subject to severe damage from flooding and has purchased over 130 of them (over 350 properties since 1989 when purchases made together with municipalities and the State of Illinois are counted); its stream program was created to restore conveyance and flood storage on the nearly 360 miles of stream in DuPage County; and its Residential Drainage Assistance Program helps residents of unincorporated areas with localized flooding. The same county page states that sump pump failures and foundation leaks are not eligible for assistance, and the county’s Drainage Division page adds that the majority of drainage systems in place cannot handle large storms and that underground springs or high water tables cannot be altered by drainage construction. Our reading of that: keeping the sump pump running through an outage is the homeowner’s responsibility, which is why the sump pump is on the essentials list for even the smallest KOHLER package we install.

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 DuPage County

Which KOHLER model fits a DuPage County home

The five air-cooled KOHLER models we install all run on natural gas or propane (field-convertible), share the RDC2 controller with the KOHLER Energy Management app, carry a 5-year/2,000-hour limited warranty covering parts, labor and travel (7- and 10-year extended plans are available), are rated for 181 mph winds and can sit as close as 18 inches from the house under NFPA guidelines, subject to local code. We recommend the cold-weather kit for any unit that will run below 32 F. Sizing in DuPage comes down to three questions we settle at the free estimate: is the home on a private well, does it depend on a sump pump, and how many central air conditioners does it have. Placement rules matter too. Where a municipality bars the front or corner side yard and requires screening in a side yard facing a street, as Wheaton does, the RESV models’ 30.6 by 28 inch steel enclosure is easier to tuck into a narrow side yard than the 47 by 26 inch aluminum RCA enclosure.

• KOHLER 10RESV (10 kW on propane, 9 kW on natural gas; installed from $8,000): essentials only, meaning furnace, refrigerator, sump pump, well pump and lights; the compact choice for tight lots.
• KOHLER 12RESV (12 kW on propane, 11 kW on natural gas; installed from $8,500): the same footprint with enough capacity for essential circuits plus one air conditioner under load management; suited to narrow lots.
• KOHLER 14RCA (14 kW on propane, 12 kW on natural gas; installed from $9,000): entry whole-house coverage for small and mid-size homes; KOHLER rates it to start and run a 5-ton air conditioner, and it is off-grid rated.
• KOHLER 20RCA (20 kW on propane, 18 kW on natural gas; installed from $10,500): whole-house coverage for most 2,500 to 4,500 sq ft homes with one central AC, with 41 kVA of motor-starting capacity.
• KOHLER 26RCA (26 kW on propane, 24 kW on natural gas; installed from $12,000): the largest air-cooled KOHLER, for large homes running two ACs under load management plus a well pump, an electric range or an EV charger.

Full specifications for each model are on the product pages, the prices and installation cost page compares all five, and existing owners can book KOHLER generator service, repair and maintenance through the same office.

DuPage County KOHLER FAQs

Who installs KOHLER generators in Naperville and Wheaton?

GSHA Services, LTD, an authorized KOHLER dealer, installs and services KOHLER generators in both cities using our own licensed electricians and gas-line technicians. Both cities sit inside our standard 50-mile service radius, measured as the crow flies from our Lake Bluff and Woodstock offices; by road, downtown Naperville is about 52 miles from Lake Bluff and Wheaton about 43 miles from Woodstock. Naperville requires an issued building permit before work starts and requires that standby generators be installed by electricians licensed by the city, so mention that requirement when you book and we will go over it before any permit is pulled. Wheaton requires a scaled plat of survey, product installation specifications and wiring and piping diagrams with the permit application, and we prepare those submittals as part of handling the permit.

Do I need a permit for a standby generator in unincorporated DuPage County?

Yes. The DuPage County Building & Zoning Department, Building Division (421 N. County Farm Road, Wheaton; 630-407-6700) lists generators among its Residential Accessory permits, applications go through the county’s Accela Citizen Access portal, and the county states that work may not begin before the permit is issued. GSHA pulls the permit; the county requires the contractor to be registered with the DuPage County Building Official before issuance, and the installation is inspected against the 2020 National Electrical Code and the 2021 International Fuel Gas Code the county has adopted.

Which gas utility do you coordinate with in DuPage County?

Nicor Gas (Northern Illinois Gas Company), which Wheaton and Woodridge both name as their natural-gas provider, which is headquartered in Naperville and whose territory covers most of northern Illinois outside Chicago. Before we quote, our gas-line technicians check whether your existing meter and piping can supply the generator’s full-load demand (179,000 to 290,000 BTU/hr depending on the model) alongside your furnace and water heater; if not, a meter upgrade by the utility is sometimes needed. If you are unsure whether Nicor serves your address, its service-area page offers a ZIP-code lookup.

Is Aurora inside your service area?

Yes. Aurora was founded in Kane County and its city limits now extend into DuPage, Kendall and Will counties. Its center is about 39 miles from our Woodstock office as the crow flies, inside our standard 50-mile radius, and about 47 miles by road, which makes Woodstock the office that serves it. Naperville and Bolingbrook are also inside the radius but are the longest drives on our DuPage list, at roughly 52 and 56 road miles from Lake Bluff; the on-site estimate is free in every case.

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

Installed from $8,000 for the KOHLER 10RESV to $12,000 for the KOHLER 26RCA. That starting package includes the generator, a standard automatic transfer switch, standard gas and electrical connections, permits and start-up; a longer gas run, a utility meter upgrade, a service-entrance-rated switch for a 200 A whole-house service or a municipal screening requirement can move the number, so we confirm the final price with a free on-site estimate. For reference, KOHLER’s MSRP for the generator alone runs from $3,946 (10RESV) to $7,546 (26RCA).

Other county pages: McHenry County · Boone County · Kane County · Will County · Cook 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: DuPage County, Illinois (Wikipedia; 2020 Census population, area, county seat, municipality table) · DuPage County Regional Planning FAQs (39 municipalities wholly or partly in the county) · Aurora, Illinois (Wikipedia; 2020 Census, county membership) · Naperville, Illinois (Wikipedia; 2020 Census, county membership, municipal electric utility) · Schaumburg, Illinois (Wikipedia; 2020 Census, county membership) · Bolingbrook, Illinois (Wikipedia; 2020 Census, county membership, city coordinates) · Wheaton, Illinois (Wikipedia; 2020 Census, county seat) · Downers Grove, Illinois (Wikipedia; 2020 Census) · Elmhurst, Illinois (Wikipedia; 2020 Census, county membership) · Lombard, Illinois (Wikipedia; 2020 Census) · Bartlett, Illinois (Wikipedia; 2020 Census, county membership) · Carol Stream, Illinois (Wikipedia; 2020 Census) · Hanover Park, Illinois (Wikipedia; 2020 Census, county membership) · Addison, Illinois (Wikipedia; 2020 Census) · OSRM routing engine, driving-distance table from the Lake Bluff (60044) and Woodstock (60098) office ZIP centers to the centers of Aurora, Naperville, Schaumburg, Wheaton, Downers Grove, Elmhurst, Lombard, Bartlett, Carol Stream, Hanover Park and Addison (queried September 10, 2026) · OSRM routing engine, driving distance from both offices to the center of Bolingbrook (queried September 10, 2026) · City of Wheaton Utilities (Nicor gas, ComEd electric) · Village of Woodridge Utility Contacts (Nicor gas, ComEd electric) · Nicor Gas (Wikipedia; customers, service territory, Naperville headquarters) · Nicor Gas service area (ZIP-code lookup) · City of Naperville Electric Utility (municipal utility, outage line) · City of Naperville Electrical Generator Safety (transfer switch, city-licensed electricians, $85 permit and inspection) · City of Naperville Generator Permit · City of Wheaton Generator permit requirements · DuPage County Building & Zoning Department (building permitting for unincorporated areas; address and phone) · DuPage County Building Projects and Permits (Generator under Residential Accessory) · DuPage County Permits and Forms (work shall not commence before permit; well and septic review) · DuPage County Contractor Registration · DuPage County Building Code (adopted codes) · DuPage County Building and Permits (code changes effective January 1, 2024) · DuPage County permit portal landing page · DuPage County Accela Citizen Access portal · DuPage County Health Department: Water (well permits, Plan Review 630-221-7045) · DuPage County Health Department: Sewage (septic permits) · DuPage County Stormwater Management: County Services for Residents (buyout program, stream program, drainage assistance, sump-pump exclusion) · DuPage County Stormwater Management: Unincorporated Drainage Program (Drainage Division statements) · NBC Chicago, June 10, 2026: ComEd outages across the Chicago area including DuPage County · GSHA Services KOHLER dealer site (authorized dealer). Distances are approximate driving miles from the nearest GSHA office, rounded to the mile.

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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