I get called to a lot of Naperville houses about three weeks too late.
Somebody closes in June, moves in, plugs a window unit into the back bedroom, and calls me in August because the breaker won’t hold. By then the panel is theirs. The seller is gone. The number I quote them is a number they could have used at the negotiating table if they had known about it in April.
None of that requires an inspector. Most of it you can see yourself, at a showing, in about ten minutes, with your agent standing right there scrolling her phone.
Here is what I would look at if I were buying in this town.
What to bring
A three-light outlet tester with a GFCI button on it. They cost about ten dollars at any hardware store on Ogden and they fit in a jacket pocket. That is genuinely the whole kit. Your phone flashlight covers the rest.
One rule before you start, and I am not being dramatic about it: do not take the cover off the panel. Do not unscrew anything. There is line voltage behind that cover that stays live with every breaker in the off position, and it is not your house yet. Everything below is looking, counting, and plugging in a tester.
Minute 1: the meter and the service entrance
Start outside, before you go in, while everyone else is admiring the landscaping.
Find the meter. Look at the pipe running up the wall to the roofline, or, in the newer subdivisions, look for where the service comes up out of the ground. What you want to see is a mast that is plumb, sealed at the top, and not pulling away from the fascia. What you do not want is rust running down the wall from the weatherhead, a conduit that has been shoved sideways by a tree limb, or a meter socket with a burn mark under it.
In the older parts of town, around the Historic District and the streets just north of the DuPage River, I still find masts that were installed when the house had a fuse box, and they look it.
Take a photo. It costs you four seconds and it is the single hardest thing to remember accurately once you are back in the car.
Minutes 2 to 3: find the panel and read it without opening it
Basement, garage, or utility closet. In split-levels and bi-levels around Cress Creek you will usually find it in the lower-level laundry area, often behind the door where nobody wants to look.
Five things, all of them printed on the outside or visible through the door:
The number on the main breaker at the top. That is your service size. 100 means 100 amps, and in a house that has since gained central air, a finished basement, and a car that plugs in, 100 is where my phone starts ringing. 200 is what most people want now. If you want the full reasoning on sizing, we wrote up what size electrical panel a Naperville home actually needs separately.
The brand name on the door. Federal Pacific, usually badged Stab-Lok, and Zinsco are the two that change my advice immediately. Both have a documented history of breakers that do not trip when they should. Challenger, Murray, and Pushmatic are less alarming but they are old, and replacement parts are getting scarce. If you see one of these names, read our piece on how to tell if a Naperville electrical panel is outdated before you write the offer.
Empty slots. Count the knockouts that are still covered. A panel with zero room is a panel that cannot accept a hot tub, an EV charger, a second-floor laundry, or a basement finish without a subpanel or a service upgrade first.
Skinny breakers. If you see a lot of half-height breakers doubled up in single slots, someone has been squeezing in circuits for years. Sometimes that is fine and the panel is rated for it. Sometimes it is not.
Whether the cover sits flat, whether there is rust along the bottom edge, and whether it smells like anything. A panel should smell like nothing at all. If there is a hot plastic smell in that room, stop the walk-through and tell the agent. That is a real finding.
Minutes 4 to 5: the tester tour
Now you use the ten dollar gadget. Six outlets, roughly one every twenty seconds.
Kitchen counter. Bathroom vanity, upstairs if there is more than one. Garage. Exterior, usually by the patio door. Unfinished basement wall.
You are looking for two things. First, the lights on the tester. Two amber lights is correct wiring. Anything else, most commonly the pattern that means open ground, tells you the outlet has three prongs but nothing actually connected to the ground screw. In houses built before the mid-sixties that is normal and expected. In a house that was flipped last year with new quartz counters, it means somebody swapped receptacles without running a ground, and I would start wondering what else they did that way. There is more on why that matters in our explainer on electrical grounding in Naperville homes.
Second, GFCI protection. Kitchens, baths, garages, exteriors, and unfinished basements all need it. Press the GFCI button on your tester at each of those locations. If the power cuts, you are protected and you can reset it at whichever receptacle has the buttons. If nothing happens at any of them, that protection is missing, and while the fix itself is cheap, its absence tells you the house has not been touched by an electrician in a long time. We covered what GFCI outlets do and why they matter if you want the longer version.
Reset anything you trip. Do not leave the fridge circuit dead behind you.
Minute 6: the kitchen, counted rather than admired
Ignore the backsplash for a second and count the receptacles along the counter run. Then look at what is plugged in and where the microwave and the fridge get their power.
A modern kitchen wants multiple 20-amp circuits serving the countertop, plus separate dedicated feeds for the dishwasher, the disposal, the microwave, and the range. What I find in a lot of Naperville kitchens that were remodeled in the nineties is a beautiful room running on the two circuits that were there in 1978. The tell is a homeowner who has learned not to run the toaster and the coffee maker at the same time. If the sellers are at the showing, that is a question you can just ask.
If the range is gas and you are the kind of buyer who wants induction later, that is a dedicated 240-volt circuit and it has to come from a panel with room for it. Same story for a car charger. We put together a panel self-assessment for EV chargers that works just as well for any large appliance you are planning to add.
Minutes 7 to 8: look up in the basement
This is the part almost nobody does, and it is the most informative two minutes of the whole walk-through.
Stand in the unfinished part of the basement or the utility room and shine your light along the joists. You are reading the actual wiring, not a report about it.
White porcelain knobs and tubes with cloth-wrapped conductors running through them: knob and tube. Common in Naperville houses built before roughly 1950. It is not automatically an emergency, but insurance carriers care about it and so should you.
Cable with a fabric or cloth jacket that flakes when you look at it: mid-century branch wiring. Same conversation. We wrote about whether old cloth wiring in a Naperville home is a fire hazard because the honest answer is more complicated than yes or no.
Cable jacket stamped AL or ALUMINUM: aluminum branch circuits, mostly 1965 through about 1973 around here. There are legitimate repair methods short of a full rewire, and there are insurance implications either way. That whole situation is covered in our post on aluminum wiring in 1965 to 1973 Naperville homes.
Junction boxes with no cover, wire nuts hanging in open air, or an extension cord stapled along a joist and feeding something permanent: that is unpermitted work, and it is usually not the only unpermitted work.
Minute 9: smoke alarms and the second floor
Walk the hallway and glance at the ceiling in each bedroom. Illinois requires hardwired, interconnected alarms with battery backup in a lot of situations, and a lot of older Naperville housing stock still has battery-only units stuck to the ceiling with adhesive.
The quick tell is whether the alarm sits on a round electrical box, which means it is wired, or flat against the drywall, which usually means it is not. Retrofitting interconnected alarms into a finished two-story is real work, and it comes up at resale constantly. Our breakdown of the Illinois smoke alarm law explains what a buyer’s inspector is going to flag.
Minute 10: ask one question about paperwork
Ask the agent whether the panel, the kitchen, or the basement finish was permitted, and get the answer in writing if you can.
This is not a technicality in this town. The City of Naperville requires a permit before any electrical work inside city limits, requires the work to be done by a state-licensed electrical contractor registered with the city, and requires compliance with the 2023 National Electrical Code. You can read the city’s electrical permit requirements yourself in about a minute.
If a basement was finished without a permit, you are the one who inherits it. You inherit the inspection when you go to sell, and you inherit it if there is ever a claim. There is more on this in our post about why DIY electrical work fails Naperville city inspections.
Sorting what you found
Not everything on that list is worth the same amount of worry. Roughly how I rank it after doing this work here for over ten years:
Walk-away territory, or at least get a real number before you go firm: a burning smell at the panel, scorch marks anywhere, a service mast pulling off the house, or knob and tube spliced into modern cable in three different places. That last one usually means the house has been worked on by four different people who each did the cheap thing.
Price-it-in territory: a 100-amp panel in a house you intend to add load to, a Federal Pacific or Zinsco panel, aluminum branch circuits, missing GFCI protection throughout, or a finished basement with no permit history.
Move-in weekend territory: a couple of ungrounded outlets in one bedroom, a dead switch, a ceiling fan on a box that needs replacing, exterior receptacles missing covers.
I am deliberately not putting dollar figures in those buckets, because they move with scope and with the season. If you want current numbers, we publish them in our Naperville residential electrician cost guide, which we update rather than leave sitting from 2023.
One more thing worth saying plainly. A home inspector is not an electrician. A good one will flag a Federal Pacific panel and note ungrounded receptacles, and that is exactly what they should do. What they will not do is tell you what a 200-amp service costs at your particular house, whether your panel can take a charger, or whether the aluminum can be remediated instead of rewired. That is a different phone call, and it is worth making before your inspection contingency expires rather than after.
Frequently asked questions
Can I do this at an open house? Yes. Everything above is looking, counting, and plugging in a tester. You are not opening anything or moving anything. If you feel odd about it, tell the listing agent what you are doing. In my experience they would rather you ask now than renegotiate later.
What if the house is a new build? Different checklist. New construction problems are usually missing circuits, poorly located outlets, and trim-out shortcuts rather than dangerous wiring. We wrote a separate pre-move-in walk-through for West Naperville new builds for that.
The listing says the panel was “recently updated.” Is that enough? No. Updated can mean a new 200-amp service with a permit and a final inspection, or it can mean somebody put a new cover on a Zinsco panel. Ask for the permit number. If there is a permit, the city has a record of it.
Should I get an electrician out before I make the offer? On most houses, no. Do this walk-through, make your offer with an inspection contingency, and bring an electrician in during the inspection period if anything above turned up. On a pre-1950 house, or one where you found knob and tube, I would make the call before you go firm.
How much of this does the seller have to disclose? Less than buyers expect. Disclosure covers known material defects, and “the panel is undersized for how you plan to live in the house” is not a defect. It is your problem to find, which is the entire reason for the ten minutes.
Want a second opinion on what you found?
If you took photos during a showing and want somebody to look at them, send them over. We do this for Naperville buyers regularly and there is no charge for a look and an honest read on whether it is a big deal.
Cob Services LLC has been doing residential work in this town for over ten years. If it turns into an actual project, you can see the full scope of what we handle on our residential electricians in Naperville page, or start from our home page if you are just getting a feel for the company.
Call (630) 427-5923. Free estimates, no trip fee, no dispatch fee, and you will be talking to a licensed electrician rather than an answering service.
Cob Services LLC 2020 Calamos Ct Suite 200, Naperville, IL 60563 (630) 427-5923 Monday through Friday, 9:00 AM to 5:00 PM. Emergency line 24/7. Illinois license #26-00032356. Licensed, bonded and insured. Serving Naperville, Lisle, Aurora, Plainfield, Bolingbrook, Downers Grove, La Grange, Hinsdale, and Burr Ridge.
About the author
Alexandr Godonoaga is the owner of Cob Services LLC and an Illinois-licensed electrician with over ten years of residential experience in Naperville and the western suburbs. He works under Illinois license #26-00032356, is ICC-certified for EV charger installation, and walks every residential estimate personally. Connect on LinkedIn.