Illustrated Catastrophes: Separation Anxiety

All references are based on the 2020 edition of the NEC.

Separation Anxiety

A close look at the top left portion of this enclosure reveals the Code violations with this mineral-insulated (MI) cable installation. The installer brought each conductor into this steel enclosure through an individual opening without complying with the requirements in Sec. 300.20(B).When single conductors carrying alternating current pass through magnetic metal such as steel, the effects of induction shall be minimized by either cutting slots in the metal between the individual openings through which the individual conductors pass, or by passing all of the conductors through an insulating wall large enough for all of the conductors of the circuit. One common method installers use is to cut one large hole in the steel wall and then attach a nonmagnetic brass plate to the enclosure and then pass the conductors through this brass plate. This installer followed another path. He drilled holes in the enclosure for two of the conductors and then connected the other two to a separately attached steel plate with individual holes. Even the locknuts on the MI cable connectors are noncompliant magnetic steel. For low-current installations, the inductive heating effects will not be too severe. For higher currents, however, there could be significant heating of the metal between the individual conductor entries.

Weatherproof Woes

I spotted this violation during a recent lunch date with my wife at a popular lobster pier. The outdoor vending machines were plugged into receptacles where the box covers were permanently flipped opened. The receptacle box is installed under a very small overhang, but I would still consider this a wet location rather than a damp one. A driving or beating rain could easily soak these receptacles. For 15A or 20A, 125V or 250V receptacles installed in wet locations, Sec. 406.9(B)(1) requires “an enclosure that is weatherproof whether or not the attachment plug cap is inserted.” This enclosure is only weatherproof when nothing is plugged into the receptacles and the covers are closed. There is an exception allowing “an enclosure that is weatherproof when the attachment plug is removed” for areas subjected to routine high-pressure spray washing, but that exception would not be applicable here. For both wet and damp locations, Sec. 406.9 requires these receptacles to be a listed weather-resistant (WR) type. Section 210.8(B)(4) requires GFCI protection for these receptacles. At present, there are no requirements for using tamper-resistant (TR) type receptacles here, but the ever-increasing requirements in Sec. 406.12 are subject to future changes.