The National Highway Traffic Safety Administration is proposing rule changes to update the electrical safety requirements for hydrogen fuel cell vehicles and mild hybrid vehicles.

One proposed change would add an optional method for post-crash electrical safety. It involves physical barriers to prevent electrical shock arising from direct or indirect contact of high-voltage sources, NHTSA said. The method affords the same level of protection against electric shock as those currently included in federal safety standards, but it would better enable the use of some innovative powertrain technologies.

Additionally, NHTSA is proposing to expand current safety standards to include United Nations regulations for electrical safety during normal vehicle operation — not post-crash. Also proposed is adding an optional method of meeting electrical isolation requirements in certain conditions.

The goal of the proposed changes is to facilitate wider use of hydrogen fuel cell and “mild hybrid” vehicles — those that use electrical systems to supplement gasoline engines and boost efficiency. Toyota Motor North America and the Alliance of Automobile Manufacturers have submitted separate petitions, seeking updates to federal safety standards to enable innovative powertrain systems. 

“Today’s proposal would provide more options in building safety into electric and fuel-cell cars and help automakers develop and sell more fuel-efficient vehicles,” said NHTSA Administrator Mark Rosekind. “U.S. consumers would be able to purchase a wider variety of vehicles with high fuel efficiency and zero or low emissions without any decrease in safety. At the same time, the proposed rule would better align NHTSA regulations with global industry standards.”

NHTSA is an agency within the U.S. Department of Transportation.

These proposed updates are consistent with international regulations and the latest version of the voluntary industry standard, SAE J1766, “Recommended Practice for Electric and Hybrid Electric Vehicle Battery Systems Crash Integrity Testing.