Electronic Vehicle Supply Equipment (EVSE)

An EVSE refers to the electrical equipment used to provide power to an EV safely and efficiently. The EVSE, also known as Electronic Vehicle Supply Equipment, is not actually the charger itself, but rather a controlled access point to the local power grid. When a vehicle plugs into an EVSE, standard communication protocols are carried out between the EVSE and the EV’s onboard charger to negotiate how much current the charger may draw. There are 3 different EVSE types that all differ in how they’re installed and how much power they can supply per charging session.

  • Level 1 Charging

L1 chargers connect to a standard 120V household outlet. While it requires no installation, L1 charging has slower charging times than its higher-leveled counterparts – taking around 24 hours to fully charge an empty battery.

  • Level 2 Charging

Level 2 chargers use a higher output 240V power source similar to what your standard dryer is plugged into. L2’s charge around 25 miles per hour, making them the choice charging station for both commercial and residential use. Additionally, every non-Tesla L2 charging station in North America uses a J1772 connector that’s compatible with all plug-in EV models in North America.

  • Level 3 DC Fast Charging

A DC Fast Charging station uses between 200-600V DC and up to 50+ kW. DCFC’s are not available for residential installations and are typically found in commercial areas or near highways. DC Fast Charging stations can charge some EV’s to 80% in as little as 20-30 minutes. A standard L1 and L2 charging station will supply AC power to an EV’s on-board charger, which will then supply DC power to the battery. DC Fast Charging, on the other hand, supplies DC power directly to the battery.

It’s important to remember that not every EV is compatible with DCFC stations due to the difference in connectors. Most Hybrids, for example, can only use L1 and L2 charging stations.

Wiring a Single EVSE

Single EVSE’s require a dedicated electrical circuit, which is the component of an electrical supply system that divides a power feed into subsidiary circuits. These electrical circuits act as the wiring pathways that travel from the power source, through wiring, to a device that requires power.

Wiring Multiple EVSE’s

All shared EVSE’s are wired on one branch circuit rated for the setup. This is an exception to the rule for dedicating a single circuit per EVSE but is approved by UL and is featured in the instructions. If you choose to wire separate branch circuits for each sharing EVSE, you’ll have to run 80A to each EVSE. If you don’t, you’ll likely trip the breaker when a single EV is charging.

Consider how you want your EVSE’s set up prior to installation. If you choose to install a small branch circuit per EVSE and then decide to activate sharing after the fact, you’ll end needing a total rewire.

EVSE Communication Capabilities

The traditional method of powering 4 EVSE’s off 80A of capacity is to provision 20A (which only amounts to 16A of charge X 125% derate) to each individual EVSE. The wiring for this requires a subpanel and 4 breakers. With this setup, however, an EV will only receive 16A even if it’s the only car plugged in. That means that even if there’s 64A available on the feeder, your charge is still limited.

Since EVSE’s can communicate their load with each other, it’s actually possible to use this communication to distribute power more efficiently. As an example – the Tesla Wall Connector 3.0 can be configured so that 1 station is considered the “master” and given control of the amps provided by the feeder, which it can then share amongst other EVSE at the same location as needed. So, if one EVSE is charging with a full 64A and a second EV plugs in to charge on the same network, the second EVSE will communicate their need for power to the master. Once that signal is received, the master will then direct half of that 64A to the second charging station. As soon as that second EVSE has completed its charging session, it will signal that it is finished and the 32A that it was utilizing will be returned to the pool.

Need a Professional Electrician?

If you’re looking for top-notch, affordable electrical contractors in the Pierce County area, look no further than Tapps Electric! From wiring upgrades to EVSE installation and more, our expert electricians provide only the best service for our customers. Give us a call today at (253) 993-4626 to get started!

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