(2) Make ground connections only to metallic cold water pipes which are in service.
(3) Connect a ground wire to the street side of an insulating joint if such a joint is present in
the metallic water pipe.
(4) If a supply tank is used in a building, connect the ground to its inlet pipe only.
b. Private water systems.
(1) Do not use a private water system as ground unless a public water system is not available.
(2) Use private water systems in preference to ground rods only if more than 10 feet of the
private water system in underground.
(3) Connect ground only to cold water pipes which are in service.
Grounded Metallic Structures.
Grounded metallic structures, such as buried tanks, conduits, and pipes may be used for protector
grounds, but only when such structures are evidently permanent.
c. Ground rods.
When grounds described above are not available, use one ground rod for each protector.
Drive the ground rod below the level of the ground.
d. Installing ground clamps.
Locate ground clamps where they will be subject to minimum disturbance and damage.
When a ground clamp is located under a sink or other fixture, place it as far up under the fixture and as
close to the wall as possible. Clean every pipe to which a ground is to be connected of paint; rust, dirt,
and other foreign matter.
Nickel, Chromium, and other finished pipes need only to be wiped off with a damp cloth.
Clean copper pipe with emery cloth lightly applied.
e. Fastening ground wire.
Fasten ground wires as shown in Figure 38.