59.4-B1)    Location: The common neutral grid system shall be grounded at intervals not greater than 1500 feet.  On branch circuits extending from a grid, where return loop paths are not available, the common neutral line conductor shall be grounded at intervals not greater than 800 feet.  Each transformer installation on a branch circuit without a loop return shall be so located that there will be one or more metallic water pipe system grounds, each of a resistance not greater than 3 ½ ohms, on each side of the transformer installation.

59.4-B1)    Location: The common neutral grid system shall be grounded at intervals not greater than 1500 1000 feet.  On branch circuits extending from a grid, where return loop paths are not available, the common neutral line conductor shall be grounded at intervals not greater than 800 500 feet.  Each transformer installation on a branch circuit without a loop return shall be so located that there will be not less than one or more metallic water pipe system grounds, each of a resistance not greater than 3 ½ ohms, on each side of the transformer installation.

59.4-B1)    Location: The common neutral grid system shall be grounded at intervals not greater than 1000 feet.  On branch circuits extending from a grid, where return loop paths are not available, the common neutral line conductor shall be grounded at intervals not greater than 500 feet.  Each transformer installation on a branch circuit without a loop return shall be so located that there will be not less than one grounds, each of a resistance not greater than 3 ½ ohms, on each side of the transformer installation.