Exposed noncurrent-carrying metal parts of switch and fuse cases, levers, and other similar parts to which leakage may occur from live parts shall be permanently grounded according to the provisions of § 39.197 (relating to grounding). Parts of machines, such as name plates, screws in wood, and similar small parts which are not liable to become alive except under very unusual circumstances are not considered as coming under this requirement and may be left ungrounded.
34 Pa. Code § 39.237