Scotchrap 20-mil-thick polyvinyl chloride (PVC)
maximum safe use voltage and label colors for
tape (manufactured by Minnesota Mining and
insulating gloves approved for Navy use.
Manufacturing Company) should be installed beneath
Before using rubber gloves, you should carefully
the seam. You may also use a 1-foot wide strip of
inspect them for damage or deterioration. To inspect
electrical grade deck covering under rubber- or
rubber gloves for tears, snags, punctures, or leaks that
vinyl-type coverings instead of heat welding vinyl.
are not obvious, hold the glove downward, grasp the
glove cuff, and flip the glove upward to trap air inside
PORTABLE ELECTRIC-POWERED TOOLS
it. Roll or fold the cuff to seal the trapped air inside.
Then, squeeze the inflated glove and inspect it for
damage. For additional information on rubber gloves,
Safety is a very important factor in the use of
refer to NSTM, chapter 300.
portable power tools and cannot be overemphasized.
The hazards associated with the use of portable power
RUBBER FLOOR MATTING
tools are electric shock, cuts, flying particles,
explosions, and so on. You should ensure portable
You must use approved rubber floor matting in
electric-powered tools are clean, properly oiled, and
electrical and electronic spaces to eliminate electrical
in good operating condition. Before you use any
mishaps and afford maximum protection from
portable electrical equipment, you should visually
electrical shock. Mishap investigations often show
examine the attached cable with plug (including
that the floors around electrical and electronic
extension cords, when used) to ensure it is in
equipment had been covered with only general-
satisfactory condition. Replace promptly any cable
purpose black rubber matting. The electrical
that has tears, chafing, or exposed conductors, and any
characteristics of this type of matting do not provide
damaged plug. Use an approved tool tester or
adequate insulation to protect against electrical shock.
multimeter to test portable electrical equipment with
There are various types of electrical grade mats or
its associated extension cord connected. When using
sheet coverings that conform to the requirements
the multimeter to check continuity of the ground
set forth in Military Specification (MILSPEC)
conductor from the tool case to the dummy receptacle,
be sure the meter reading is less than 1 ohm. With the
multimeter still connected between the tool case and
To ensure the matting is completely safe, you must
ground, bend or flex the cable to see if the meter
promptly remove from the matting surfaces all foreign
resistance remains 1 ohm or less. If the resistance
substances that could contaminate or impair its
varies, you might have broken conductors in the cord
dielectric properties. The dielectric properties of
or loose connections.
matting can be impaired or destroyed by oil, imbedded
metal chips, cracks, holes, or other defects.
Other safe practices in the use of portable
electric-powered tools include the following:
If the matting is defective for any reason, cover
the affected area with a new piece of matting.
Before you use a tool, inspect the tool cord and
Cementing the matting to the deck is not required, but
plug. Do not use the tool if the cord is frayed or
is strongly recommended. This prevents removal of
its plug is damaged or broken. Never use
the mat for inspection and cleaning, which would
spliced cables, except in an emergency.
leave the area unprotected. If the mat is not cemented,
Before you use a tool, arrange the portable
stencil an outline of the proposed mat on the deck.
cables so you and others will not trip over them.
Inside the mat outline, stencil "ELECTRIC-GRADE
The length of extension cords used with port-
MAT REQUIRED WITHIN MARKED LINES." Use
able tools should not exceed 25 feet. Extension
3/4 inch or larger letters.
cords of 100 feet are authorized on flight and
Electrical insulating deck covering should be
hangar decks. Extension cords of 100 feet are
installed so there are no seams within 3 feet of an
also found in damage control lockers, but are
electrical hazard. Where this is not possible,
labeled FOR EMERGENCY USE ONLY.
thermoplastic deck coverings, such as vinyl sheet
Do not use jury-rigged extension cords that
manufactured by Lonseal, Inc., should be fused
have metal handy boxes on the receptacle ends
chemically, heat welded, or heat fused with a special
hot air gun. With rubber deck coverings, fusing with
of the cord. All extension cords must have
nonconductive plugs and receptacle housings.
heat is not possible. A 3- or 4-inch wide strip of #51