NEC Article 625 outlines the safety measures involved in electric vehicle charging. Learn more about what it says specifically about ground fault protection.

NEC Article 625 and all of its subsets deal with Electric Vehicle Power Transfer Systems, or in simpler terms, anything that involves the charging of an electric vehicle (EV). Everything in this Article relates to the safe practice of charging EVs with Electric Vehicle Supply Equipment (EVSE, also known as an EV charging station or EV charger). It is also very expansive, detailing the mandated procedures for a given EVSE, such as manufacturing specifications (x. cable length), installation methods, rules for different product variations (portable, permanent, wireless charging, etc.), and more. While every part of this Article has merit, we will look at a few subsets that have the most purpose for your safety, which include:

This subsection is very straightforward, stating that your charging system needs to be (UL) Listed. This, in more detail, means that the charging system has passed the rigorous safety testing requirements made and carried out by Underwriters Laboratory.

This subsection deals with the rating (as in electrical amperage rating) of the charging system. It states that the charging system needs to have an acceptable supply of electricity to meet the demands of the charging system. What that means is the breaker supplying the electricity to the charging system needs to be rated above the charging system’s capacity (if you have a 32-amp charging station then you need it to be supplied by a 40-amp breaker). There are 2 ways to get around this however, which include:

A. If there is an energy management system (EMS) involved that can supply load management to the EVSE. The EMS can be for either 1 or multiple charging stations, but it needs to be set to have the maximum load allowed be in accordance with the feeder (breaker) of the equipment. Most EMS systems are usually for designed commercial & industrial EV charging applications that involve numerous vehicles.

B. The other way to get past is by having a charging system with an adjustable amperage setting. This will allow a user to set the charging station to an amperage setting lower than the breaker's allowance of electricity, therefore operating at an acceptable current level. NEC Article 625.54: This part of the Code simply states that there needs to be Ground Fault Circuit Interrupter (GFCI) protection involved in every charging system. This is also (partially) explained in more detail in two other subsections. In 625.22 it states that a Listed “personnel protection system” is needed, which implies GFCI protection but can include more in the system. Also, in 625.60(D) it states that the charging system needs to have a visible indication and reset options on the product (which implies GFCI test & reset capabilities).

This NEC section specifies the safety measures needed in the charging equipment for an electric vehicle in extensive detail. To meet all of these stringent requirements the NEC states that any EVSE used should be UL Listed so that it meets the guided standards of protecting the user charging the vehicle from harm in any environment. Also note, UL has different testing thresholds for EV chargers for indoor and outdoor use, so make sure to check what your EVSE is Listed for specifically to make sure you don’t use unsafe charging equipment in the harsh outdoor elements.