Code Quiz

Jun 27, 2007 3:35 PM, By Steven Owen

                

Q. When installing a high-impedance grounded neutral system, for a 480V, 3-phase system, the following question has arisen. Which of the following choices best describes the proper routing for the grounded conductor of the system?

1. It shall be run (installed) in the same raceway with the other phase conductors. This is the only choice. No other options are available.
2. It shall be run (installed) in a non-metallic raceway with the other phase conductors, following the requirements of 300.5(I)(Exception No. 2).
3. It shall be permitted to be run (installed) in the same raceway with the other phase conductors if desired; however, it shall also be permitted to be installed in a separate raceway by itself with any routing chosen by the installer.
4. It must be insulated, bare, or covered, and installed so as not to be easily damaged, with or without a raceway for protection.

Answer: C

As per 250.36(D), “The conductor connecting the neutral point of the transformer or generator to the grounding impedance shall be permitted to be installed in a separate raceway. It shall not be required to run this conductor with the phase conductors to the first system disconnecting means or overcurrent device.”

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.