Two EVs, One House: Charging Both Without Upsizing Your Service

The second EV shows up faster than people expect. A lease ends, one spouse switches, and suddenly there are two cars in the Brooklyn driveway and one charger on the garage wall. The instinct is to assume you need a bigger service — a 400-amp upgrade, a new Con Edison feed, a torn-open wall in a brownstone that didn't want one. Usually you don't. There are three legitimate ways to charge two cars on the service you already have, and the right one depends on your panel, your parking, and how far you actually drive.

Why two chargers look impossible on paper

EV charging is a continuous load, so the code requires the breaker and the conductors to be sized at 125% of the charger's maximum draw. That's the rule that makes the math ugly.

Run it for two independent 48-amp chargers: each needs a 60-amp circuit, so you're dedicating 120 amps of breaker capacity. On a 200-amp service that's most of the house before the range, the dryer, or the AC gets counted. Few NYC homes have that headroom sitting idle, which is why the naive version of this project turns into a service upgrade.

The important word there is independent. The code has a different answer for chargers that talk to each other.

Option 1: two chargers, one circuit, one energy management system

Under NEC 625.42, where an energy management system (EMS) provides load management of EV charging equipment, the load counted against the service and feeder is the load the EMS permits — not the sum of the chargers' nameplate ratings. That's the provision that makes sharing legal.

In practice, a listed EMS lets two 48-amp-capable chargers share one 60-amp circuit and allocates current between them. Do the arithmetic first: a 60-amp circuit carries 48 amps continuously, so with both cars plugged in each side lands near 24 amps — roughly half speed. Unplug one and the other can take the full allocation. You've added a second charging position without consuming more service capacity.

A NYC caveat worth knowing. The 2025 NYC Electrical Code — adopted by Local Law 128 of 2024, effective December 21, 2025 — is the 2020 NEC with NYC amendments, and it governs permits filed on or after that date. Newer NEC editions have reshuffled this material: in the 2026 NEC, the energy management requirements that used to sit in Article 750 were relocated to Article 130, whose second part covers power control systems. That is not what a NYC filing is measured against today. Have a licensed master electrician confirm which edition governs your job before anyone designs around a provision from a newer book.

Option 2: two chargers, two circuits, still managed

Sometimes one shared circuit doesn't fit the property — the cars park at opposite ends, or the garage and the curb spot sit on different walls of a two-family. Run two circuits and keep the EMS in the middle, capping combined draw at a number your service can carry.

You spend more on conductors and panel space, but the capacity result is the same: what counts against your feeder is what the EMS permits. Usually the answer where each unit wants its own charger.

Option 3: one charger and a schedule

The cheapest answer is often the correct one. Two EVs in a household rarely both need a full charge on the same night. The Department of Energy's Alternative Fuels Data Center puts Level 2 charging at roughly 25 miles of range per hour, with units running from 2.9 kW to 19.2 kW — so your rate depends on the equipment. Even mid-range, one charger covers two typical NYC commutes on alternating nights.

If your combined daily driving is modest — and in a city of short trips, it usually is — one charger and a habit beats an electrical project. Try it for a month before you spend anything.

What we check before quoting any of the three

• The load calculation. It decides everything. Spare capacity is a number, not an opinion, and the calculation is what the filing stands on.
• Panel and feeder space. Physical breaker slots and busbar rating are separate questions from service amperage.
• That the EMS is listed for the purpose. A charger app that "shares power" is not automatically a code-recognized energy management system.
• Ground-fault coordination. Hardwired EVSE comes with its own ground-fault protection, and stacking a GFCI breaker upstream of it invites recurring nuisance trips. Where the charger plugs into a receptacle instead, the rules are different and GFCI protection may be required — settle that distinction before a second unit gets added to an existing install.
• Filing and approvals. In NYC a licensed master electrician pulls the permit and the work gets a DOB inspection. Co-ops and condos usually need board sign-off first, and a real increase in service amperage means coordinating with Con Edison.

Before you assume you need a bigger service

If someone quoted a service upgrade for a second EV without running a load calculation or mentioning load management, get a second look. Chazon Electric is licensed and insured, works across all five boroughs, and can tell you which option your house actually supports — see EV charger installation or, if the calc really does come up short, panel upgrades. Call (718) 924-8062 and we'll walk your panel with you.