N.J. Stat. § 39:3-54.25
Notwithstanding the provisions of section 2 of P.L. 1968, c.439 (C.39:3-8.1), an authorized employee of a public utility company who, as part of the official duties of a public utility employee, is required to use a motor vehicle owned or leased by him or a member of his family in the performance of his duties may affix on that motor vehicle a magnetic sign, provided by the public utility company, that displays the corporate logo of the public utility company. The sign shall be placed on the exterior of the front driver's side door of the motor vehicle.
The sign may only be displayed while the motor vehicle is being used on a public highway by the authorized public utility employee in the performance of his official duties as a public employee, and shall be removed from the motor vehicle when the vehicle is not being used in the performance of these duties.
N.J.S. § 39:3-54.25