Service manual

STP 11-25R13-SM-TG

T - 27

d. On mobile facilities, the vehicle will be grounded through a commercial power grounding system

when commercial power is utilized. The grounding rod and grounding conductor furnished with the

generator used for supplying power to the vehicle will be installed when generator power is utilized. The

grounding rod provided with the vehicle will be installed in either case. Specific techniques for installing

ground rods are in TM 5-765.

e. Noncurrent-carrying metal frames of electrically powered equipment and tools, such as hand-

held power tools, will be connected to a grounding conductor. Portable tools protected by an approved

system of double insulation, or its equivalent, need not be grounded.

f. Records will be maintained attesting to the adequacy of the electrical grounding system in the

maintenance, repair, or calibration facility. The grounding system will be of both proper design and

installation. The grounding system will be evaluated at 12-month intervals by facilities engineer

personnel to assure consistency of minimal requirements as specified in the National Electrical Code,

supplemented by this bulletin. A high resistance measurement instrument, such as a ZM-21/U or

equivalent, with a minimum output of 500 volts shall be used.

T-35. Fire Protection and Prevention.

NOTE: The following rules apply to all fires:

a. Immediately deenergize the circuit or equipment affected.

b. Call the fire department. In a few cases, the means of calling the fire department may be much

closer at hand than the electric power controls. In such cases, the fire department should be called first,

but circuits should be deenergized before the fire fighting begins.

c. Control the fire insofar as possible with the correct type of fire fighting equipment until fire-

fighting personnel arrive.

d. Carbon dioxide (CO

) or Halon 1211 or 1301 is the preferred fire extinguisher for use on

electrical fires (Class C). Other fire extinguishers rated for Class C fires may also be used.

e. Soda-acid, water, or foam extinguishers will not be used on electrical fires since water and foam

are conductive and can result in electrical shock.

f. Fire extinguishers must be inspected monthly in accordance with TM 50687 to insure

serviceability.

g. Do not use gasoline, benzene, ether, and similar flammable cleaning fluids or either energized

or deenergized electrical apparatus.

h. Do not use alcohol for cleaning equipment as it damages most types of insulating varnishes.

i. Do not use alcohol for cleaning near energized electrical equipment from which a spark might

be received.