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User and
Installation Guide
It shall be sized for the largest grounding electrode conductor required among all the
available electrodes.
(a) Metal Underground Water Pipe. A metal underground water pipe in direct contact with
the earth for 10 feet (3.05m) or more (including any metal well casing effectively
bonded to the pipe) and 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. Continuity of the grounding path or the bonding
connection to interior piping shall not rely on water meters. A metal underground water
pipe shall be supplemented by an additional electrode of a type specified in Section 250-
81 or in Section 250-83. The supplemental electrode shall be permitted to be bonded to
the grounding electrode conductor, the grounded service-entrance conductor, the
grounded service raceway, or any grounded service enclosure.
250-83. MADE AND OTHER ELECTRODES.
Where none of the electrodes specified in Section 250-81 is available, one or more of the
electrodes specified in (b) through (d)* below 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 lightning rods) shall
not be less than 6 feet (1.83m) from any other electrode of another grounding system.
(a) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than 8 feet (2.44m)
in length and shall consist of the following materials, and shall be installed in the fol-
lowing manner:
(1) Electrodes of pipe or conduit shall not be smaller than 3/4-inch (15.87mm) in
diameter, nonferrous rods, or their equivalent shall be listed and shall not be less
than 1/2 inch (12.7mm) in diameter.
(2) Electrodes of rods of iron or steel shall be at least 5/8 inch (15.87mm) in diameter.
Stainless steel rods less than 5/8 inch (15.87mm) in diameter, nonferrous rods, or
their equivalent shall be listed and shall not be less than 1/2 inch (12.7mm) in
diameter.
(3) The electrode shall be installed such that at least 8 feet (2.44m) except that, where
rock bottom is encountered, the electrode shall be driven at an oblique angle not to
exceed 45 degrees from the vertical or shall be buried in a trench that is at least 2 1/2
feet (762mm) deep. The upper end of the electrode shall be flush with or below
ground level unless the aboveground end and the grounding electrode conductor
attachment are protected against physical damage as specified in Section 250-1167.