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FPN: See Sections 547-8 and 547-9 for special grounding and bonding requirements for agricultural buildings. (a) Metal Underground Water Pipe. A metal undergroUnd water pipe in direct contact with the earth for 10 ft (3.05 m) or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or sections or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors.r~i~ (1) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment. (2) Supplemental Electrode Required. A metal underground water pipe shall be supplemented by an additional electrode of a type specified in Sections 250-50 or 250-52. Where the supplemental electrode is a made electrode of the rod, pipe, or plate type, it shall comply with Section 250-56. The supplemental electrode shall be permitted to be bonded to the grounding electrode conductor, the grounded service-entrance conductor, the nonflexible grounded service raceway, or any grounded service enclosure. !ic~"~iJ Exception: The supplemental electrode shall be permitted to be bonded to the interior metal water piping at any convenient point as covered in Section 250-50, Exception. Where the supplemental electrode is a made electrode as in Section 250-52(c) or (d), that portion of the bonding jumper that is the sole connection to the supplemental grounding electrode shall not be required to be larger than No.6 copper wire or No.4 aluminum wire. frcCmnnnt'llIlr] (b) Metal Frame of the Building or Structure. The metal frame of the building or structure, where effectively grounded. (c) Concrete-Encased Electrode. An electrode encased by at least 2 in. (50.8 mm) of concrete, located within and near the bottom of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 20 ft (6.1 m) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than ~-in. (l2.7-mm) diameter, or consisting of at least 20 ft (6.1 m) of bare copper conductor not smaller than No.4. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means. ~~ (d) Ground Ring. A ground ring encircling the building or structure, in direct contact with the earth at a depth below the earth's surface of not less than 2~ ft (762 mm), consisting of at least 20 ft (6.1 m) of bare copper conductor not smaller than No. 2.~cnm;;;5iI . . 250-52. Made and Other Electrodes Where none of the electrodes specified in Section 250-50 is available, one or more of the electrodes specified in (b) through (d) shall be used. Where practicable, made electrodes shall be embedded below permanent moisture level. Made electrodes shall be free from nonconductive coatings such as paint or enamel. Where more than one electrode is used, each electrode of one grounding system (including that used for air terminals) shall not be less than 6 ft (l.83 m) from any other electrode of another grounding system. Two or more grounding electrodes that are effectively bonded together shall be considered a single grounding electrode system. (a) Metal Underground Gas Piping System. A metal underground gas piping system shall not be used as a grounding electrode. (b) Other Local Metal Underground Systems or Structures. Other local metal underground systems or