Charging Up EVSE: Site assessments for electrical vehicle charger installation

Published On
Feb 15, 2022

Electrical vehicle use is on the rise, and so is the need for charging infrastructure at residential, commercial and industrial applications. One of the most essential steps for installing electric vehicle supply equipment (EVSE) is performing a site assessment, which is typically performed by qualified electrical contractors. The following information provides basic guidance for completing the site survey and ultimately the EVSE installation. This article provides insight and raises awareness to some important elements of installing electric vehicle chargers, which the NEC refers to as EVSE.

The assessment should start by determining if the power source or service is adequate. Capacity of the source is important for all loads connected to it, not just EVSE. This specific part of the site survey typically involves an inspection of the service or feeder panelboard to verify the existing loads. Sometimes on smaller services or sources, a calculation should be performed to verify capacity. Remember that, based on the load profile of EVSE, it is considered a continuous load, which is defined in Article 100 as a load in which the maximum current draw is expected for 3 hours or more. This operating characteristic drives other NEC sizing requirements for branch circuit conductors and overcurrent protective devices. See sections 625.41 and 42.

Another important aspect of installing electrical vehicle supply equipment is the required branch circuit. Section 625.40 indicates that “each outlet installed for the purpose of charging electric vehicles shall be supplied by an individual branch circuit. Each circuit shall have no other outlets.”

Generally, EVSE requires an individual branch circuit. That requirement applies where an outlet is installed specifically for the purpose of charging an electric vehicle and is generally clear about branch circuit requirements for level 2 and level 2 fast-charging equipment. With level 1 EVSE (125V, portable plug-in type), the requirement is less clear, but there are factors that help with the determination.

It is important to consider that Section 625.5 requires all equipment covered by Article 625 to be listed. Listed equipment is usually provided with manufacturer’s installation instructions, which are required to be followed in accordance with Section 110.3(B).

As an aside, while Section 625.40 does not require an individual branch circuit for the portable (Level 1 plug-in) EVSE, the load profile for this equipment is often at least 80% or more of a general-purpose branch circuit rating, which in dwellings is typically 15A or 20A.

In addition, EVSE are continuous loads as indicated in Section 625.42. Unwanted tripping could result if EVSE is connected to a circuit without capacity for the load. If the manufacturer’s installation and use instructions specify installing an individual branch circuit, then 110.3(B) would take precedent over the provisions in 625.40, and an individual branch circuit should be installed.

Installation requirements

The installation requirements for EVSE vary among manufacturers. Install EVSE in accordance with all manufacturer recommendations in addition to applicable local, state and federal codes and regulations.

Mount EVSE such that wall-mounted outlets are not more than 1.2 meters (48 inches) above the ground. Provide a minimum of 600 millimeters (24 inches) clearance around all sides of outdoor free-standing EVSE. Provide bollards, curbs or wheel stops to protect EVSE from vehicles.

A few other aspects of EVSE installation are to provide a disconnecting means that is readily accessible from EVSE for circuits rated more than 60A or more than 150V to ground in accordance with NEC requirements. Disconnecting means must be lockable in the open position.

Locate receptacles for cord-and-plug connected EVSE in a location within 6 feet of the EVSE that is fastened in place and to avoid physical damage to the flexible cord.

Ground EVSE in accordance with the manufacturer requirements, standard grounding practices and the NEC . In addition to violating the NEC , an improper or inadequate grounding configuration may cause problems at start-up and long-term. Provide an equipment grounding conductor in accordance with those identified in Section 250.118. Project specifications often require separate, properly sized equipment grounding conductors in feeder and branch circuit raceways. Connect noncurrent-carrying EVSE equipment to the equipment grounding conductor with a separate bonding jumper, where required.

With an eye on installing a dependable, Code-compliant electric vehicle charger, refer to the NEC for all specific minimum requirements. For more complete EVSE installation and maintenance requirements, refer to ANSI-NECA 413, Standard for Installing and Maintaining Electric Vehicle Supply Equipment (EVSE), which supplements the NEC by addressing quality and workmanship aspects of these installations.

About the Author

Michael Johnston

Executive Director of Standards and Safety, NECA

Michael Johnston is NECA’s executive director of standards and safety. He is a member of the NEC Correlating Committee, NFPA Standards Council, IBEW, UL Electrical Council and NFPA’s Electrical Section. Reach him at mj@necanet.org.

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