By Alexandr Godonoaga, Owner and Lead Electrician, Cob Services LLC. Illinois Electrical Contractor License #26-00032356. ICC-certified. Naperville, IL.
The second EV is where this gets interesting.
The first one is easy. Somebody buys a Model Y, we run a 60-amp circuit to the garage wall, and they charge overnight without thinking about it again. Then eighteen months later the other car in the household gets replaced, and now there are two plugs and one panel, and the homeowner calls me expecting to hear that they need a service upgrade.
Usually they don’t. That’s the short version. Most Naperville houses that can support one Level 2 charger can support two, as long as you stop assuming both cars need full power at the same time.
Here’s how I actually approach these.
Start with how much charging you need, not how much you want
This is the part people skip.
A 48-amp charger pulls 11.5 kW. A 32-amp charger pulls about 7.7 kW. In a sedan doing roughly 3.5 miles per kWh, that 32-amp charger puts back about 27 miles of range per hour. In an F-150 Lightning or an R1S, closer to 17.
Now take a normal overnight window. Say you plug in at 10 p.m. and leave at 6:30 a.m. That’s eight and a half hours. At 32 amps, a sedan picks up somewhere around 220 miles. At 24 amps, which is what each car gets if two of them are splitting a 60-amp circuit, you’re still looking at roughly 160 miles per car, per night.
I have never had a Naperville customer drive 160 miles in a day and do it again the next day and the next. Commutes here run 15 to 40 miles round trip. Even a heavy week doesn’t outrun that.
So the honest answer, most of the time, is that two cars sharing one circuit will both be full every single morning and nobody in the house will ever notice the difference. The exception is real, though, and I’ll get to it below.
The three ways to wire two chargers
Two fully independent circuits
Each charger gets its own breaker, its own wire, its own everything. Simplest to understand, most expensive, and the one that most often forces a panel upgrade.
Two 48-amp chargers means two 60-amp breakers. Continuous loads get sized at 125%, so you are asking your panel to carry 120 amps of dedicated EV capacity on top of the furnace, the AC, the range, the dryer, the well of miscellaneous stuff. On a 200-amp service with a full house behind it, the load calculation usually doesn’t come out in your favor.
It can work if you drop both chargers to 32 amps on 40-amp breakers. That’s 80 amps of demand instead of 120, and it fits in a lot more houses. Nobody thinks to ask for this, but it’s often the cheapest path to two working chargers.
One circuit, two chargers, power sharing between them
This is what I install most often now.
The chargers talk to each other. One is set as the leader, the rest are followers, and the leader hands out current so the total never exceeds what the circuit can carry. When only one car is plugged in, it gets everything. When both are plugged in, they split.
Tesla’s implementation handles up to six Gen 3 Wall Connectors in one group, with power distributed across them so the total drawn from the panel or a single circuit stays inside safe limits. Five followers connect to the leader’s own wireless access point, so this doesn’t depend on your house Wi-Fi staying up. Wallbox does something similar across its Pulsar line.
One thing worth knowing before you buy hardware: the ChargePoint Home Flex has no power sharing feature between two home units. It’s a good charger and I install plenty of them, but if you’re planning a two car shared circuit, that’s a real constraint. I go through the differences between the main units in my comparison of the Tesla Wall Connector, ChargePoint, and Wallbox.
Mixed brand households are the awkward case. A Tesla and a Rivian can’t share a circuit through Tesla’s group management, because the follower has to be a Wall Connector too. In that situation I’ll usually put both cars on Wall Connectors and use an adapter on the non-Tesla, or run two smaller independent circuits, depending on what the panel allows.
One circuit with an external load management device
If the constraint isn’t the circuit but the whole service, a load management device watches total house draw and throttles or pauses the chargers when the dryer and the oven and the AC all come on at once. The National Electrical Code allows this explicitly. Article 625 lets an EVSE be counted at its adjusted setting rather than its nameplate when the setting is controlled and locked, and Article 750 covers the energy management system itself.
Practically, this is how a house with a 100-amp service ends up with two chargers instead of a $4,000 service upgrade. It isn’t free and it isn’t always the right call, but it’s on the table more often than most homeowners realize. I wrote about when a panel upgrade is genuinely necessary and when you can dodge it in this breakdown of EV charger panel upgrade costs.
What your panel will actually allow
None of the above matters until somebody runs the numbers on your specific house.
Rough guide based on what I find in Naperville garages:
A 200-amp panel in a house built after about 2000, gas furnace, gas range, gas water heater, has room for two chargers sharing 60 amps almost every time. Often room for two independent 40-amp circuits.
A 200-amp panel with an electric range, electric dryer, and a heat pump is tighter than people expect. Shared circuit, yes. Two independent circuits, usually no.
A 150-amp panel, which shows up in a lot of the 1970s and 80s stock around Hobson Village and the older sections east of Washington, needs a real load calculation before anyone promises anything. Sometimes it works with load management. Sometimes we’re talking about a panel upgrade.
A 100-amp panel with a full slate of electric appliances is almost always a service upgrade conversation.
If you want to sanity check your own situation before calling anyone, I put together a self-assessment guide for figuring out whether your panel can handle an EV charger. Doubling the load doesn’t change the method, just the numbers.
One more thing about physical panel space: two chargers means two double-pole breakers, so four slots. I’ve walked into plenty of panels with capacity on paper and no room on the bus. Tandem breakers sometimes solve it, sometimes the panel doesn’t accept them, and occasionally we add a small dedicated subpanel in the garage instead, which also shortens the wire runs if the panel is on the far side of the house.
The Naperville details that catch people out
Naperville runs its own municipal electric utility, which means the rules here are not the ComEd rules your neighbor in Lisle or Downers Grove is working under. Two things matter for a two charger install.
First, the permit. Any wiring upgrade needs a City of Naperville building permit, and the City requires a completed Residential Load Calculation Worksheet to go with the electrical permit application. For a single charger this is a formality. For two, it’s the document that decides your project. If the worksheet doesn’t support the load, you’re not getting the permit, and no amount of arguing at the counter changes that. We fill this out before quoting, not after.
Second, the money. The City offers an incentive of up to $500 per charging station, and there’s a condition in it that trips up two car households specifically: the stations have to be hardwired and permitted with the City. A NEMA 14-50 outlet with a portable connector hanging off it doesn’t qualify. If you were planning to save a few hundred dollars by putting in two outlets instead of two hardwired units, you’re giving up more than you’re saving. There’s more on that tradeoff in my post on NEMA 14-50 outlets versus hardwired chargers. The incentive also ties to the City’s Renewable Energy Program contribution, so read the terms before you assume the $500.
Worth noting: the federal 30C tax credit that used to cover 30% of home charger installs expired on June 30, 2026. If you’re reading pricing advice written before this summer, it’s out of date.
What it costs
Adding a second charger to a shared circuit at the time of the first install is the cheap version. You’re already trenching or fishing wire, already pulling one permit, already there. The incremental cost is the second unit and the second breaker.
Coming back a year later to add the second charger costs more, because it’s a separate mobilization, a separate permit, and often a rework of the first circuit to a larger conductor. If you know a second EV is coming within two years, tell your installer on the first visit and have them size the wire for it now. Six gauge copper instead of eight costs very little extra while the wall is open and saves a full second project later.
Full pricing on single charger installs, with real quote breakdowns, is in my post on what EV charger installation actually costs in Naperville.
When two shared chargers are the wrong answer
I said the exception is real, so here it is.
Shared circuits are a bad fit if somebody in the house does high mileage on an unpredictable schedule. Realtors, contractors, anyone driving 150+ miles most days and coming home at random hours. If both cars land in the garage at 9 p.m. nearly empty and one of them leaves at 5 a.m., you want dedicated capacity, and you may want the panel upgrade that comes with it.
It’s also the wrong answer if one of the vehicles charges slowly for its own reasons and can’t make up the difference. If a car is already underperforming on a dedicated circuit, splitting that circuit makes it worse. That’s usually a separate problem, and I walk through diagnosing it here.
Questions I get asked about this
Can I just plug two cars into one charger with a splitter? There are Y-splitter products that alternate between two vehicles on a single unit. They work, they’re cheaper, and I don’t love them. You lose the ability to charge both simultaneously, most aren’t listed for permanent hardwired installation, and the City incentive requires a hardwired station. For a household that’s committed to two EVs long term, two units on a shared circuit is a better build.
Does power sharing need internet? No. Tesla’s group management runs over the leader unit’s own access point, so it keeps working when your router doesn’t. You’ll want Wi-Fi for firmware updates and app monitoring, but charging doesn’t depend on it.
Will two chargers on one circuit pass inspection in Naperville? Yes, when it’s engineered and documented properly. The inspector wants to see that the total configured current can’t exceed the circuit rating, and that the settings are locked. Sloppy versions of this install do fail, along with a handful of other recurring issues I’ve catalogued in the code violations we see most often on Naperville EV inspections.
Do I need a bigger service just because I have two EVs? Not automatically. The number of cars matters less than your panel’s existing load and whether you need both at full power simultaneously. I’ve done two charger installs on 150-amp services and turned down single charger jobs on 200-amp services that were already maxed out.
What if the second EV is a truck? Trucks change the math. An F-150 Lightning with the extended range battery is roughly 131 kWh. Filling that from low on a shared 24 amps takes more than one night. If a truck is one of the two vehicles and it regularly runs down, lean toward dedicated circuits.
Getting a straight answer for your house
I’d rather look at your panel than guess. A load calculation on a two charger project takes about twenty minutes on site and it’s the difference between a quote you can trust and a number somebody made up over the phone.
We install two charger setups across Naperville and the surrounding suburbs, including Aurora, Plainfield, Lisle, Bolingbrook, Downers Grove, Hinsdale, La Grange, and Burr Ridge. Same crew every time, and I run the site walk myself.
More on our EV charger installation service, or see what else we handle as residential electricians in Naperville.
Request an estimate or call (630) 427-5923.
Cob Services LLC 2020 Calamos Ct, Suite 200, Naperville, IL 60563 (630) 427-5923 Illinois Electrical Contractor License #26-00032356 Monday to Friday, 9:00 a.m. to 5:00 p.m.