Q. When grounding the ferromagnetic envelope of skin effect-heating systems, what are the grounding requirements?

  1. Grounding is not required.
  2. Grounding one end only with an equipment-grounding conductor is required.
  3. Grounding both ends with an equipment-grounding conductor is required. Grounding any intermediate points in between the ends is also permitted.
  4. GFCI protection (Class C, 30mA trip) is required.

Answer: C

Per 426.44 of the 2008 NEC, when grounding the ferromagnetic envelope of skin effect-heating systems, grounding both ends with an equipment-grounding conductor is required. Grounding any intermediate points in between the ends is also permitted. The requirements of 250.30 do not apply to this type of installation.

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.