625.42 Rating.
Code Change Summary: Revised code language recognizes some electric vehicle (EV) charging equipment with adjustable ratings.
Some modern EV charging equipment is equipped with adjustable load ratings allowing EV chargers to be installed in older homes with small electric services, or other service configurations where limited wiggle room is left for installing additional loads.
In an older home with a 60-amp electrical service, installing a 30-or 40-amp EV charging circuit can push the service load calculation over the edge to the point that the service size needs to be upgraded. Some manufacturers solved this dilemma years ago by creating EV chargers that can be adjusted to a lower setting to accommodate limited remaining load capabilities of an electric service.
The problem prior to the code change was not having NEC® language that permitted this type of solution. In the 2020 NEC®, language was added to allow such installations only for fixed-in-place EV charging equipment with a few conditions that must be followed.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.
2017 Code Language:
625.42 Rating. The equipment shall have sufficient rating to supply the load served. Electric vehicle charging loads shall be considered to be continuous loads for the purposes of this article. Where an automatic load management system is used, the maximum equipment load on a service and feeder shall be the maximum load permitted by the automatic load management system.
2020 Code Language:
625.42 Rating. The power transfer equipment shall have sufficient rating to supply the load served. Electric vehicle charging loads shall be considered to be continuous loads for the purposes of this article. Service and feeder shall be sized in accordance with the product ratings. Where an automatic load management system is used, the maximum equipment load on a service and feeder shall be the maximum load permitted by the automatic load management system.
Adjustable settings shall be permitted on fixed-in-place equipment only. If adjustments have an impact on the rating label, those changes shall be in accordance with manufacturer’s instructions, and the adjusted rating shall appear with sufficient durability to withstand the environment involved on the rating label. Electric vehicle supply equipment with restricted access to an ampere adjusting means shall be permitted to have ampere ratings that are equal to the adjusted current setting. Sizing the service and feeder to match the adjusting means shall be permitted. Restricted access shall prevent the user from gaining access to the adjusting means. Restricted access shall be accomplished by at least one of the following:
(1) A cover or door that requires the use of a tool to open
(2) Locked doors accessible only to qualified personnel
(3) Password protected commissioning software accessible only to qualified personnel