Where grounding wires are used to ground metallic sheaths, armors, conduits, frames, casings and other metallic enclosures, such grounding wires must comply with the following conditions:
(1) The cross-sectional area (size) of the grounding wire shall be at least one-half the cross-sectional area (size) of the power conductor where the power conductor used is No. 6 A.W.G. or larger.
(2) Where the power conductor used is less than No. 6 A.W.G., the cross-sectional area (size) of the grounding wire shall be equal to the cross-sectional area (size) of the power conductor.