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 ELECTRICAL
General Wiring-Continued
n Deterioration of conductor insulation:
n Sagging or improperly supported conduit:
n Condition of electrical devices, receptacles, switches, electrical
equipment, motors, etc.:
n Romex wiring exposed to physical damage:
7.2.11 Ground Test (Lightning Protection):
n Lightning Protection System Requirements:
The resistance of the primary and secondary system shall not exceed 10 ohms. When
the primary system is installed in wet ground, its resistance shall not exceed 3 ohms. To
obtain continuous and reliable protection, the systems shall be maintained to function
efficiently. A higher resistance caused by any parts of the system being corroded,
broken, or poorly installed may cause lightning discharged or current to take a less resis-
tant path through the building and its contents thereby causing fires and explosions.
Deterioration is most active at the places where the conductors enter the ground.
n Semiannual Inspection:
Ensure that the primary and secondary systems are visually inspected semiannually for
evidence of corrosion and broken connections. Repairs for all discrepancies found
during these inspections shall be made immediately.
n Annual Test:
Ensure that the lightning protection system is tested electrically annually. The results of
these tests, together with the description of the defects noted and repairs made, shall be
submitted to the person responsible for the efficient operation of the lightning protec-
tion systems and entered in the station records.
n Equipment Used:
Electrical tests consist of measuring the ohms resistance of the system to ground and the
ohms resistance of any grounding system or individual ground connection. An instru-
procedures outlined below are based on the use of a testing instrument which is
equipped with a test ground. If an instrument such as a megger is used, two instrument
grounds are needed. The manufacturer's instructions for using the instrument should
be followed carefully to avoid damage to the instrument and to insure valid results.
7-25
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