effective electrical contact. Areas of electrical contact shall be sharp points or knife edges where possible.
(d) The electrical equipment and compressed air supplies shall be interlocked with a ventilation system so that the equipment cannot be operated
unless the ventilating fans are in operation. [33:Chapter 15]

516.16 Grounding. All metal raceways, the metal armors or metallic sheath on cables, and all non- current-carrying metal parts of fixed or portable electrical equipment, regardless of voltage, shall be grounded and bonded. Grounding and bonding shall comply with 501.30, 502.30, or 505.25, as applicable.