680.23(B)(3) Equipment Grounding Provisions for Cords. Other than
listed low-voltages lighting systems not requiring grounding
wet-niche luminaires that are supplied by a flexible cord or
cable shall have all exposed non–current-carrying metal parts
grounded by an insulated copper equipment grounding
conductor that is an integral part of the cord or cable. This
grounding conductor shall be connected to a grounding terminal
in the supply junction box, transformer enclosure, or other
enclosure. The grounding conductor shall not be smaller than
the supply conductors and not smaller than 16 AWG.