(a)
Ground connections to metallic piping systems shall be made on the street side
of water meters, which might interrupt the continuity of the underground
metallic pipe systems, unless otherwise provided in subsection (b), but
connections may be made immediately inside building walls to secure
accessibility for inspection and test. When water meters are located outside
buildings or in concrete pits within buildings where piping connections are
inbedded in concrete flooring, the ground connection may be made on the
building side of the meters, if they are suitably shunted.
(b) When the making of a ground to a piping
system outside the meter or other device would involve a long run, connection
for equipment or wire runways, not for circuits, may be made to the water
piping system at a point near the part to be protected, if there are no
insulating joints in the pipe to prevent a good ground. In such cases care
shall be taken to electrically connect all parts of the piping system liable to
create a hazard, if they become alive, to shunt the pipe system where necessary
around meters, and so forth, in order to keep the connection with the
underground piping system continuous. Gas piping systems within buildings shall
not be used for purposes of this rule, except that gas piping need not be
insulated from otherwise well-grounded electrical fixtures and if the making of
another ground connection for a fixture would involve a long run and the
fixture is, therefore, not within reach of plumbing or plumbing fixtures, the
gas piping may for small fixtures be utilized as the sole ground connection. If
so used the gas piping and water piping systems within the building shall be
grounded at their points of entrance. Reference should also be made to
§§
39.65 and
39.66 (relating to ground
conductor; and nature of ground connection).
(c) The ground connection to metallic piping
systems shall be made by sweating the ground wire into a lug attached to an
approved clamp and firmly bolting the clamp to the pipe, after all rust and
scale have been removed, or by soldering the ground connection into a brass
plug which has been tightly screwed into a pipe fitting or, where the pipe is
of sufficient thickness, screwed into a hole in the pipe itself, or connection
may be made by other equivalent means. The point of connection shall be as
readily accessible as possible, and the position should be recorded. With bell
and spigot joint pipe it may be necessary to connect to several lengths where
circuits or equipment of large current-carrying capacity are being
grounded.
(d) Artificial grounds
shall be located, where practicable, below permanent moisture level, or failing
this at least 6 feet deep. Each ground should present not less than 2 square
feet surface to exterior soil. Areas where ground water level is close to the
surface shall be used when available.
