However, if the equipment was originally provided with
plug into the receptacle to be tested. Touch the probe of
a grounding cord and plug, this type cord and plug must
the other test lead of the meter to the ship's structure.
The reading should be less than 1 ohm.
be retained throughout the life of the device. Equipment
stamped DOUBLE INSULATION or DOUBLE
If a receptacle tests unsatisfactory, it should be
INSULATED must have only two prong plugs and
immediately repaired or tagged with a red danger tag to
cords. At the discretion of the inspection authority,
indicate that it must not be used Keep a record of the
three-prong plugs and cords may be installed on other
locations of all grounded receptacles and the dates they
equipment if the ground conductor can be conveniently
were tested.
connected to the exposed metal parts, and the
modification does not compromise the equipment
operation or the enclosure integrity.
ELECTRICAL EQUIPMENT
ABOARD SHIP
The Navy has adopted a policy to use commercially
CAUTION
available tools and equipment, when feasible. No
specific guidance can be provided to cover all portable
A wide range of miscellaneous portable
tools and equipment. Much of the burden of accepting
electric equipment may be received aboard
and rejecting portable electrical and electronic
ship without being provided with a cord that
equipment falls on the electrical or electronic officer or
has a grounding conductor and a grounded
other designated personnel to perform the initial
plug that is not plastic encased. This
inspection.
equipment includes galley equipment (fruit
juice extractors, food-mixing machines,
APPROVAL FOR USE
coffee pots, toasters); office equipment
machines,
(adding
addressograph
Nonconducting cased portable tools and equipment
machines); shop equipment (key duplicating
do not require grounding cords or plugs, provided the
machines, valve grinders, mica undercutter,
equipment meets both of the following requirements:
hot plates); medical equipment (infrared
lamps, ultraviolet lamps, sterilizers); barber
1. Passes an initial inspection for rugged, safe
shop equipment (hair clippers); and laundry
construction, and
equipment(flatirons)
2. Has a minimum of 1 megohm dc resistance from
any phase to any exposed metal part (such as
When electrically operated equipment is issued to
chuck housing, mounting screws, ear plug jacks,
the ship without a grounding conductor or grounded
or antennas) or metal chassis.
plug, it must have a three-conductor flexible cable and
grounded plug installed before it is used.
The following equipment is acceptable for use aboard
(Nonconducting plastic-cased portable electric tools are
ship:
excluded.)
If the portable tool or equipment has the words
The three-conductor flexible cable should be type
DOUBLE INSULATION or DOUBLE INSULATED
SO or ST color-ceded black, white, and green, as listed
stamped on its enclosure, it is assumed to be of rugged,
in the Navy Stock List of General Stores, Group 61. For
safe construction. This stamping designation is an
general use, the plugs should be bladed and have
underwriters requirement; however, this requirement is
U-shaped grounding prongs. These plugs are available
only applicable to selected type of equipment. Portable
for use with small and large diameter cords. Stub-type
equipment, which hasn't been stamped DOUBLE
plugs that can be made watertight (formerly designed as
INSULATION or DOUBLE INSULATED, will be
type SNR) are now furnished with plastic shells.
acceptable if they meet the two requirements listed
above.
PERMANENTLY MOUNTED EQUIPMENT
All equipment, when tested with a Megger, must
have at least 1 megohm resistance between either sides
Electrical equipment that is permanently mounted
of the line and any exposed metal of the equipment.
to the hull of the ship does not require an additional
When equipment meets the above criteria, it is
ground wire. However, equipment installed with shock
acceptable for use with a two prong plug and cord.
mounts does require an external ground cable.
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