Q. Where a transient voltage surge suppressor (TVSS) is installed, the TVSS shall comply with which of the following?

  1. The rating of the TVSS shall be equal to or greater than the maximum continuous phase-to-ground power frequency voltage available at the point of application.
  2. TVSS shall be a listed device.
  3. TVSS 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. TVSS shall not be installed on ungrounded systems, impedance grounded systems, or corner grounded delta systems unless listed specifically for use on these systems.
  5. All of the above.

Answer: E

All are these are requirements of a TVSS installation. See Sections 285.1, 285.3, 285.5, and 285.6 of the NEC.

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.