Q. Where a surge arrester is installed on a circuit operating at less than 1,000V, it shall comply with all but which of the following?

  1. The rating of the surge arrester shall be equal to or greater than the maximum continuous phase-to-ground power frequency voltage available at the point of application.
  2. The surge arrester shall be identified for the application.
  3. Surge arresters shall be marked with short-circuit current rating and shall not be installed at a point on the system where the available fault current is in excess of that rating.
  4. Surge arresters shall not be installed on ungrounded systems, impedance grounded systems, or corner grounded delta systems unless listed specifically for use on these systems.

Answer: B

As per 280.4(A)(2), surge arresters installed on circuits of less than 1,000V shall be listed.

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at necexpert@aol.com.