Grounding electrode system

A grounding electrode system is the set of electrodes that ties the electrical system and equipment grounds to the earth, and they are connected to it by a grounding electrode conductor (GEC). Common electrodes include a metal underground water pipe, the building's metal frame, a concrete-encased electrode (also called a Ufer ground), a copper ground ring, and driven rods or buried plates. Whichever ones are present must be bonded together into one system. A metal water pipe counts as an electrode only if it is in direct contact with the earth for at least 10 ft, and it must be supplemented by at least one other electrode because the piping may be or later become plastic. Most PV systems are functionally grounded rather than solidly grounded. In those systems the ac equipment grounding conductor to the distribution equipment can act as the connection to ground for ground-fault protection and for equipment grounding of the array. Extra auxiliary electrodes are allowed at ground-mounted and roof-mounted arrays and may connect straight to the array frame or structure. A ground-mount structure can itself count as an electrode if it meets 250.52. Inverters often have a marked GEC terminal on a grounding busbar for this connection. Soil conditions affect how the system is designed: sandy or gravelly soil has high resistivity and needs multiple electrodes for lightning grounding.

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• sentence 3: support check: partial - The passage calls a water pipe in direct contact with the earth for 10 ft the preferred electrode and says it must be supplemented by another, citing plastic piping. It does not say the pipe counts as an electrode only if it meets the 10 ft contact. -->