Bonding of Conductive Materials and Equipment

For grounded systems, noncurrent-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the _____ to establish an effective ground-fault current path.

a) ground
b) earth
c) electrical supply source
d) none of the above

See answer and applicable Code reference

The correct answer is: c) electrical supply source

The general requirements for bonding and grounding electrical systems are outlined in Sec. 250.4 of the NEC. As noted in 250.4(A)(4), "Normally non-current-carrying electrically conductive materials that are likely to become energized shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path."