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EV charger on a 100 amp panel: load management vs. panel upgrade

Checked Oct 22, 2026. A 100A service doesn't automatically mean you need a panel upgrade. Whether you do depends on your home's actual load, how much you drive and which code edition your city uses. Only a licensed electrician's load calculation can answer it for your address.

How common is this?

In northern Illinois, a 2022 ComEd study found roughly two-thirds of homes in its territory had service of 100A or less, about 2.2 million homes. (ComEd EV Energy Management System Pilot executive summary (PDF), Dec 19, 2025, checked Oct 22, 2026)

Your options, cheapest first

Level 1 (the cord that came with the car). Rewiring America says it gives about 50 miles of charge overnight from a regular outlet, with no upgrade. (Rewiring America, checked Oct 22, 2026)
A lower-amp Level 2 charger. Standard Level 2 chargers use 40A or more; Rewiring America says a 16A Level 2 charger provides at least 100 miles of charge a night. Many chargers let you set the amps lower. (Rewiring America, checked Oct 22, 2026) Under the 2023 National Electrical Code (NEC), an adjusted charger rating counts only if the adjustment is restricted-access and the adjusted rating is shown on the label. (NEC 625.42 text, checked Oct 22, 2026)
A smart splitter (circuit sharing). Shares one 240V circuit, often the dryer's, between two appliances and pauses one while the other runs. Rewiring America lists DryerBuddy, SplitVolt and NeoCharge and puts them at $400–$700; some are plug-in, others must be hardwired by an electrician. (Rewiring America, checked Oct 22, 2026)
An energy management system (EMS) or load-managing charger. It watches the whole home's load and slows or pauses EV charging when the house gets close to the panel limit. Under NEC 2023 section 625.42(A), when a qualifying EMS manages the charger, the charger load counted on the service is the maximum the EMS allows, not the charger's full rating. (NEC 625.42 text, checked Oct 22, 2026) The 2026 NEC moves this concept to "Power Control Systems" (section 120.7), with the setting limited to 80% of the monitored breaker rating. (NEC 120.7 text, checked Oct 22, 2026)
A smart panel. Manages every circuit, not just the charger. Rewiring America names Span and Koben and puts them at $3,000–$5,000 plus installation. (Rewiring America, checked Oct 22, 2026)
A panel or service upgrade. ComEd's pilot report used $5,000 as a conservative average saving from avoiding a panel amperage upgrade and said costs can be as high as $15,000. Those are the report's planning assumptions, not quotes. (ComEd pilot summary (PDF), checked Oct 22, 2026)

What load management does and doesn't change

It changes how much of your service the charger is counted as using. It does not shrink the charger's own circuit: EV charging is treated as a continuous load, and the branch circuit is still sized to the charger's full output at 125%. (Entogo, NEC 625.42 explainer, checked Oct 22, 2026)
It doesn't add capacity. If you're also planning a heat pump, a second EV or other big loads, ask whether the whole plan fits before choosing.
For an existing home, the NEC lets an electrician base the calculation on actual measured demand (one year of data, or 30 days recorded) taken at 125%, before adding the new load (NEC 220.87). (Entogo, checked Oct 22, 2026) Ask your electrician which method they used.

Does it work in practice?

ComEd ran a 12-household pilot with Emporia's EMS (the Vue monitor and PowerSmart software). The report says the EMS reliably managed EV charging within panel limits, participants reported minimal impact on charging convenience, and local permitting for EMS installs varied considerably between communities. It was a small pilot, so treat it as an early signal. (ComEd pilot summary (PDF), checked Oct 22, 2026)

Questions to ask before you accept an upgrade quote

What load calculation did you do, and which NEC edition does our city enforce?
Would a lower-amp charger, a splitter or an EMS pass inspection here instead?
Does the utility need to be involved (meter pull, service change), and how long does that take?
Does my utility rebate require a specific installer or charger? See Illinois rebates.

Compare quotes line by line with the quote checklist, or go back to install costs.