2017 National Electrical Code  By: Robert Key | May 06, 2020 Electric vehicle (EV) charging is not new, as Article 625 was introduced to the National Electrical Code with the 1996 edition. The following year, the Toyota Prius became the first mass-produced (hybrid) electric vehicle. More followed, including Tesla, Nissan, and Chevrolet. Until recently, however, the only viable method for charging an electric or hybrid vehicle was via a direct connection to a power supply, either from premises wiring or at a charging station. For the 2017 Code cycle, both definitions and requirements have been added to Article 625 for the purpose of regulating another type of EV charging: wireless power transfer, or wireless charging. Before we examine the Code requirements, let’s answer a couple of important questions. First, how does wireless charging work? Second, how efficient is this technology? How is wireless charging accomplished? Although various methods have been experimented with, the technology that has emerged as the clear winner is magnetic resonance. Just as a transformer produces a current in the secondary windings without any electrical connection to the primaries, the electric current is transferred by creating a magnetic field between a transmitting pad mounted on the ground and a receiving pad attached to the underside of the vehicle. How efficient is this technology? Invented by an MIT professor in the mid-2000’s, magnetic resonance charging was first employed to charge cell phones and started out at around 60 percent efficiency. It was convenient, but inefficient. Before long however, it reached 75 percent and up, with many systems now performing above 90 percent efficiency. Efficiency is also dependent on the proximity of the transmitting and receiving pads. For example, the new 120kW wireless charging system developed by the Department of Energy at Oak Ridge National Laboratory boasts a 97 percent efficiency rating, but to achieve that, the two pads must be within 15 centimeters (6 inches) of each other. Now, on to the Code requirements. Here are the 2017 NEC definitions related to wireless vehicle charging:
The regulations for WPT and WPTE are found at part IV in new sections 625.101 and 625.102. Here are some important parts of the section. (Italics have been added for emphasis)
(A) Type. The charger power converter, if not integral to the primary pad, shall be provided with a minimum Type 3R enclosure rating. (B) Installation. If the charger power converter is not integral to the primary pad, it shall be mounted at a height of not less than 450 mm (18 in.) above the floor level for indoor locations or 600 mm (24 in.) above grade level for outdoor locations. (C) Primary Pad. The primary pad shall be installed on the surface, embedded in the surface of the floor with its top flush with the surface, or embedded in the surface of the floor with its top below the surface. There are also requirements regarding acceptable enclosure types, protection of the primary cable, and others. It is likely that before long, we will see wireless charging stations in parking lots and similar locations. Clearly, EV’s are here to stay for the foreseeable future. Methods of charging, EV’s themselves, and the Code will continue to evolve as time goes on.
2020 National Electrical Code By: Robert Key | Dec 06, 2021 Electric vehicles are likely here to stay, but they are a rapidly evolving technology. Lighter lithium-ion type batteries have made electric cars, bicycles, motorcycles, and more, a reality. The code-making panels have significantly revised Article 625 for the 2020 National Electrical Code (NEC) to regulate the safety of electric vehicle charging. Even the title of the Article has changed, from “Electric Vehicle Charging” to “Electric Vehicle Power Transfer System.” Acronym School There are a lot of abbreviations in Article 625. Perhaps a brief acronym primer would be helpful.
What’s New for 2020? What’s new for 2020? Quite frankly, a lot. There is an abundance of gray highlighted text which indicates a revision, as well as many (N)’s in the margin, which show where a new definition or subsection is found. One of the newer developments for electric vehicles is wireless power transfer. This technology is not actually new. Cell phones have had that capability to be charged wirelessly for some time now. This method uses coil induction, similar to a transformer, to charge a vehicle wirelessly. It is reported to be up to 91% efficient over a 10-inch air gap. The concept of wireless power transfer is far from new, however, having been pioneered by Nikola Tesla who patented the idea in 1897! Another recent development requiring adaptation of the NEC is EV Power Export and Bidirectional Current Flow. What this means is that in addition to being recharged by premises wiring, an electric vehicle can act as an alternate power source for premises wiring or other outlets when the primary current source is not available. The Informational Note provided for the definition of EVPE reminds us that these are sometimes referred to as bidirectional EVSE (electric vehicle service equipment). 2020 NEC New Code Requirements Probably the most important new code requirement is found in Section 625.54, Ground-Fault Circuit-Interrupter Protection for Personnel. In past editions of the Code, an electric vehicle charging receptacle may or may not have required GFCI protection, depending on the location. If it was installed in one of the locations found at Section 210.8, Ground-Fault Circuit-Interrupter Protection for Personnel, then it was required, but if not, then no protection was stipulated. With the adoption of the 2020 NEC, all electric vehicle charging receptacles shall have ground-fault circuit-interrupter protection for personnel. Other new Code requirements include:
These are just some of the special requirements for the installer of an Electric Vehicle Power Transfer System. It is always wise to read through Article 625 prior to starting the installation, especially if you don’t do this often. The EV user is relying on the electrician and inspector to keep them safe. |
Electric vehicle supply equipment (evse) or wireless power transfer equipment (wpte) shall be _____.
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