(A) Grounding shall be to water pipes when available, with a jumper around the water meter. National Electric Code Article 250 will be applicable, with attention directed to 230-79(C), 250-80, 250-81, 250-83(c)-2 and Table 250-94.
(B) The purpose of grounding is safety. Grounding falls into two categories: system grounding and equipment grounding.
(1) SYSTEM GROUNDING is the connecting of the neutral conductor of the wiring system to the earth. An accidental grounding of a current-carrying conductor, will result in a short circuit causing a fuse or a circuit breaker to open, thereby disconnecting the line conductors.
(2) EQUIPMENT GROUNDING, or grounding non-current-carrying parts of the installation, is the grounding of the steel raceway, service equipment and metal enclosures of equipment, which is accomplished by running a wire from the neutral connection in the main service switch and the meter socket to the water piping system on the street side of the meter.
(C) National Electric Code grounding rules are as follows.
(1) NEC 250-81. Where available on the premises, a metal underground water pipe shall always be the grounding electrode.
(2) NEC 250-92(a); NEC 250-50(a), (b). Metal grounding electrode conductor enclosures shall be electrically continuous from the cabinet to the grounding electrode.
(3) NEC 250-92(a). If the metal enclosure is not electrically continuous, it must be bonded at each end to the grounding conductor.
(4) NEC 250-115. A ground clamp approved for the purpose shall be used to connect the grounding electrode conductor to the grounding electrode.
(5) NEC 250-112. Connection should be on the street side of the water meter or bonding required around valves, meter, unions and the like.
(6) Grounding wire. The size of grounding wire is found in NEC Table 250-94.
(Prior Code, § 152.19)