How Long Does Generator Installation Take?

Most North Shore homeowners, whether in Wilmette, Northbrook, or Winnetka, can expect a whole house generator project to take 3 to 8 weeks from a signed quote to the day the unit powers on. That surprises people, because the actual installation work, the concrete pad, the new gas line from your Nicor or North Shore Gas meter, the wiring, and the transfer switch, is usually done in 1 to 3 days. Almost every extra week comes from two things: waiting on your village to review the permit, and waiting on the generator itself to arrive.

This guide walks through each step in order, with real North Shore examples, so you know what is happening during the weeks when nothing visible seems to be going on at your house.

How Long Does the Whole Project Take, Start to Finish?

Short answer: Plan for 3 to 8 weeks total. A simple project in a village with fast permit review can finish closer to 3 weeks. A project that lands right after a big storm, when every village sees a spike in applications, can stretch past 8.

Permit review and equipment lead time can often run at the same time rather than back to back, which is one reason a good installer's timeline can beat simple addition. Our Illinois generator cost guide covers what each phase adds to your total project cost, not just your total wait.

Step 1: The Site Visit and Sizing Consultation

Short answer: A licensed electrician visits your home, checks your panel and gas meter, and recommends a generator size, usually within a few days of your first call.

This step moves fast because it depends only on scheduling. The electrician looks at your electrical panel, checks your Nicor or North Shore Gas meter capacity, and walks the yard for a spot that meets the clearance rules in NFPA 37, the national fire standard for stationary engines. That standard allows a listed generator as close as 18 inches from your house wall, but at least 5 feet from any window, door, or vent that opens.

You will also get a size recommendation here. Our generator sizing guide explains how square footage, heating type, and central air all factor into that number before you sign anything.

Step 2: Permits, the Longest Step

Short answer: Permit review is usually the single longest step in the whole project. Timelines vary a lot by village, and they slow down further right after a major storm.

Every North Shore village requires at least an electrical permit for a standby generator, and most also require a gas permit for the new fuel line. Our Illinois generator permit guide covers the statewide picture: a plat of survey, a site plan, a single line electrical diagram, and spec sheets for the unit and transfer switch.

How long that review takes depends entirely on where you live. Glenview's Development Center lists qualifying residential generators for its Same-Day Review program: a complete application submitted before 1 p.m. on a business day can be approved that same day. Northbrook and Deerfield route generator permits through standard review instead, which typically takes longer. Our Northbrook, Glenview & Deerfield permit breakdown and our Evanston, Wilmette & Skokie permit breakdown lay out the fees and review paths for six North Shore villages.

Cook County's own generator permit checklist, used as a public example by unincorporated areas, asks for a plat of survey no more than five years old plus a full plan review before work can begin, a process documented in the county's generator installation requirements. That kind of full plan review is exactly why permit review, not the physical install, eats most of your calendar.

One more thing to plan around: applications spike every time ComEd has a multi-day outage, the way it did after the July 2026 storms. If your neighbors just lived through a long outage, expect your village's review queue to be longer than usual for a few months afterward.

Step 3: Ordering the Generator and Waiting for It to Arrive

Short answer: Standard generator sizes are usually easier to get quickly. Larger units or load-managed systems can take longer to ship, so ask about current stock before you sign.

Generator supply has improved since the shortages of the early 2020s, but lead times have not fully returned to normal. A common, mid-size unit is more likely to be on a local distributor's shelf, while a bigger unit or a system with a load management module may need to be special ordered. Our Generac vs. Briggs & Stratton comparison covers the tradeoffs between brands if availability ends up shaping your decision.

The good news is that this step usually runs in parallel with permit review rather than after it. A well organized installer orders the unit as soon as the quote is signed, so it is often sitting in a warehouse, ready to go, by the time the permit comes back approved.

Step 4: Installation Day, Pad to Power

Short answer: Once the permit is approved and the generator is on site, the physical work usually takes 1 to 3 days.

A typical install starts with the concrete or composite pad, then the new gas line from your meter, then the electrical wiring and the automatic transfer switch that lets the generator take over from ComEd power safely. Our transfer switch installation page explains why that switch is required on every standby system, not an optional add-on. Larger homes, tricky panel locations, or a longer gas line run can push a straightforward install closer to 3 days than 1.

This is the part homeowners picture when they think about "installing a generator," but it is usually the shortest phase of the entire project, not the longest.

Step 5: Inspections and Utility Sign-Off

Short answer: After installation, an electrical inspection and a gas inspection confirm the work meets code. Scheduling those can take anywhere from a few days to about two weeks, depending on your village's inspector availability.

The electrical inspection checks the wiring, grounding, and the transfer switch's backfeed protection, the safeguard that keeps your generator from sending power back into ComEd's lines and endangering utility crews. The gas inspection pressure tests the new fuel line to confirm there are no leaks. Both inspections are usually scheduled through your village's building department once your installer requests them, and your installer typically handles the scheduling for you.

If either inspection turns up an issue, the crew fixes it and the inspector returns, which can add a few more days. This is uncommon with an experienced installer who already knows your village's requirements.

Step 6: Startup, Testing, and Handoff

Short answer: Once inspections close out, the installer starts the generator, confirms it transfers power correctly, and sets its weekly self-test schedule, usually the same day.

Your installer runs a full test transfer, simulating a power outage to confirm the generator starts automatically, the transfer switch moves your home onto generator power, and everything shuts down cleanly once ComEd power returns. They will also walk you through the unit's self-test schedule and basic maintenance, which our generator maintenance guide covers in more detail for the years after installation.

A Fast Timeline vs. a Slow One

Short answer: A straightforward project in a village with quick review can finish in about 3 weeks. A project competing with a post-storm permit backlog, or waiting on a special-order unit, can take 8 weeks or more.

Picture two North Shore homeowners signing a quote on the same day. One lives in Glenview, submits a complete application before 1 p.m., and qualifies for Same-Day Review. Their generator was a standard size already in the installer's warehouse. Permits, equipment, and scheduling all line up, and their system is powered on inside of a month.

The other homeowner signs their quote three days after a major ComEd outage. Their village's permit queue is backed up with applications from neighbors who just lived through the same outage. Their home also needs a larger, load-managed system that has to be special ordered. Between the review backlog and the equipment wait, their project stretches past two months.

Same process, same paperwork, very different calendars. The village you live in and the moment you decide to start both matter as much as the installer you choose.

How to Avoid Delays

• Start in the off season. Applications spike right after storms. Signing a quote in a calm month instead of the week after an outage keeps you out of the backlog. Our guide to the best time of year to install a generator in Chicago breaks the calendar down month by month.
• Confirm your gas meter capacity early. If your meter needs an upgrade from Nicor or North Shore Gas, finding that out during the site visit avoids a surprise delay after the permit is already filed.
• Choose an installer who knows your village. Submitting the wrong permit form, or missing a document your village always asks for, is one of the most common causes of delay we see.
• Ask about equipment availability before you sign. A standard size that is already in stock can shave weeks off a special-ordered, load-managed system.
• Be available for inspections. Scheduling delays on your end, not just the village's, can add unnecessary days to an otherwise fast project.

Frequently Asked Questions

How long does it take to install a whole house generator?

Most North Shore projects take 3 to 8 weeks from signed quote to power-on. The physical installation itself is usually done in 1 to 3 days. The weeks in between are mostly permit review and equipment lead time, not work happening at your house.

What is the single longest step in a generator installation?

Permit review. Northbrook and Deerfield route generator permits through standard review, which typically runs longer than a few days, while Glenview offers Same-Day Review for a qualifying residential generator submitted before 1 p.m. Review times also slow down after a big storm, when applications spike across every village.

Can I speed up my generator installation timeline?

Yes. Start in the off season rather than right after a storm, confirm your gas meter capacity during the site visit instead of after the permit is filed, and choose an installer who already knows your village's permit packet, since the wrong form is one of the most common causes of delay.

Do equipment shortages still delay generator installation in 2026?

Less than during the pandemic years, but lead times have not fully returned to normal. Standard sizes like 22 kW units are usually easier to get quickly than larger or load-managed systems, so asking your installer about current stock before you sign is worth the five minute conversation.

Is the actual installation day the slow part?

No. Once the permit is approved and the unit is on site, crews typically finish the concrete pad, gas line, wiring, and transfer switch in 1 to 3 days. The waiting happens before that day, not during it.

The clearest way to get a real number for your own address is to start the process. A site visit costs you nothing but a little time, and it is the step that turns "3 to 8 weeks" into an actual date on your calendar. Fill out the form below and we will connect you with one local licensed and insured electrician who can walk you through what your specific village and your specific home will need.