bending or twisting the cable causes a change in
Additionally, this equipment must be "hard wired" to the
resistance, the strands in the grounding conductor are
power source vice having a cord with a plug attached
broken and the cable must be replaced.
TESTING ELECTRICAL EQUIPMENT
The SNR plug must be checked on equipment and
extension cord. Using a megohmmeter, measure the
Before using portable electrical equipment for the
insulation resistance between the brass shell and each
first time, test the plug connections of the equipment for
contact on the plug. Push on, pull on, twist, and bend
correct wiring. Do the testing in a workshop equipped
the cable while you take measurements. If the
with a nonconducting surface workbench and approved
resistance measures less than 1 megohm, check for
rubber deck covering. Conduct the test according to
twisted bare wires in the plug. Rewire a defective plug
current PMS procedures.
and replace the brass shell of the plug with a
nonconducting plastic (nylon) shell. If the plug has to
Portable and Mobile Equipment
be replaced due to wear and tear, renew the plug tip and
replace the brass plug shell with a nylon shell. Reuse
All portable and mobile electrical equipment must
brass shells only if the nylon plug shells are not in stock.
be periodically tested and visually inspected. A list of
In this case, rewire and retest the brass shell plug for
such equipment must be established noting the locations
temporary use until the nylon shell becomes available.
and serial numbers. The following items should be
There are two sizes of nylon plug shells. One size is
included:
used for 0.425-inch-diameter cables or smaller, the other
1. Portable, hand-held electric tools that are
size for 0.560-inch-diameter cables.
permanently loaned out to other shipboard
departments or divisions
WORKMANSHIP
2. Electric equipment that is frequently touched,
such as hot plates, coffee makers, toasters,
Cord conductors must be fastened securely and
portable vent sets, movie projectors, and office
properly to wiring terminals. Aboard ship in portable
equipment.
equipment, extension cords, portable receptacles, and
plugs, the conductor ends are crimped or soldered into
All faulty equipment must be removed from service
standard eyelets (or hooks where the terminal screws are
until they are repaired and properly safety checked.
not removable). If eyelets or hooks are not available,
twist the strands of each conductor together tightly and
Bladed Plugs (Round or U-shaped Contact)
form into an eyelet or a hook. Then, coat the formed
eyelet or hook with solder to hold the strands together
Before testing a bladed plug, check to see that the
unless the manufacturer's instructions forbid tinning of
insulation and contacts are in good condition and that
the leads. There must be no loose strands to come in
the conductors are secured properly under the terminal
contact with metal parts. This would place line potential
screws. Using a volt-ohmmeter, measure the resistance
on the metal shell of the plug when it is partially inserted
from the ground contact to the equipment housing. The
in an energized receptacle. A fatal hand-to-hand
measurement must be less than 1 ohm. Move or work
electrical shock can result if the receptacle is on the end
the cable around by bending or twisting it. A change of
of an energized extension cord and has its metal case
resistance indicates broken strands in the grounding
raised to line potential (of opposite polarity to that on
conductor. This means the cable must be replaced
the shell of the plug) by loose conducting strands at the
cord connection to the receptacle.
Navy SNR Plugs
Examine all cords to make sure they are
You must examine the type SNR plugs to make sure
connected properly to their terminals. Remove
the insulation and contacts are in good condition and that
damaged plugs and cords that are improperly connected,
the conductors are secured properly under the terminal
torn, or chafed from service. (NOTE: Don't cut open
screws. Then check to see that the plug is clean and that
molded rubber plugs and receptacles for examination.)
the contacts (in particular the ground contact) are free
of hangover fringes of molded insulation that could
If the grounding conductor connected to the metallic
prevent making good contact. Measure the resistance
equipment casing is inadvertently connected to a line
from the ground contact to the equipment housing.
contact of the plug, a dangerous potential will be placed
Again, the measurement must be less than 1 ohm. If
on the equipment casing. The person handling the
2-54
