Quantcast Chapter 12 Electrical Safety

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TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
whether a circuit is de-energized or not, it must be
12-1. Human factor.
assumed that the circuit is energized and dangerous
The protection of human life is paramount. Electri-
until such time it is proven otherwise. It is also
cal equipment can be replaced; lost production can
important to regard exposed copper as energized
be made up; but human life can never be recovered
and treat it accordingly since copper is rarely used
nor human suffering ever compensated. The princ-
except to carry current. When working near electric-
ipal personnel dangers from electricity are that of
ity, do not use metal rules or flashlights, or metallic
shock, electrocution, and/or severe burn from an
pencils, and do not wear watch chains, finger rings
electrical arc or its effects, which may be similar to
or other objects having exposed conducting mate-
that of an explosion. The major contributors to
work-related electrical accidents are unsafe condi-
a. De-energization. Personnel, who must work on
tions or unsafe practices. The most common unsafe
de-energized equipment, should be protected
conditions are damaged, defective, burned or wet
against shock hazard and flash burns that could
insulation or other parts; improperly guarded or
occur if the circuit were inadvertently re-energized.
shielded live parts; loose connections or strands
To provide this protection, the circuit must first be
pulled loose; and equipment not grounded, or poor
de-energized. Check applicable up-to-date draw-
or inadequate grounding connection. Unsafe prac-
ings, diagrams and identification tags to determine
tices include failing to de-energize equipment being
all possible sources of supply to the specific equip-
repaired or inspected; assuming an unsafe position
ment. Open the proper switches and/or circuit
breakers for each source in order to isolate the
near energized equipment; using tools or equipment
equipment to be worked on. In cases where visible
too near bare energized parts; and misusing tools or
blade disconnecting devices are used, verify that all
equipment. Safety manuals provided by the mili-
blades are fully open. Drawout-type circuit breakers
tary services are based upon the National Electrical
should be withdrawn to the fully disconnected posi-
Safety Code (NESC) which establishes general safe
tion. Do not consider automatic switches or control
practices for construction, maintenance, and opera-
devices to be a disconnecting means for personnel
tion of all electric utility systems. The rules con-
tained in these manuals are considered mandatory
b. Tagging and lock-out. All employees should
and must therefore be referenced at all times. Any
plan for safety by following all lockout procedure
deviations from these procedures must be agreed
rules before beginning work on any equipment.
upon by the safety director. In general, to improve
Four steps vital to any good lockout procedure are:
safety to personnel and avoid accidents, special at-
tention must be directed to the following:
(1) Lock the equipment to prevent its use. Any
energized equipment should be shut down by turn-
a. Be alert. Alertness is particularly essential on
ing off power or closing valves to eliminate the pos-
new assignments until safe habits are formed, but
sibility of electrocution, the inadvertent operation of
should never be relaxed since conditions often
machinery, or the release of hazardous materials.
(2) Identify the equipment to let other employ-
b. Be cautious. Caution should be exercised at all
ees know it is not in service, when the lockout was
initiated, and the purpose of the lockout.
c. Develop safe habits. Safe habits result from
repeated alertness and caution, and continuous ad-
(3) Clear the area to assure that other employ-
ees are a safe distance from the equipment before
herence to the rules.
the lockout is tested.
d. Know your job. Have complete and thorough
(4) Test the equipment to verify that the equip-
information before proceeding.
ment cannot be energized and that the lockout ren-
e. Observe the rules. The rules and instructions
ders it inoperable. Before the test, check to be sure
applying to a variety of cases, both electrical and "
that all interlocks are engaged.
mechanical in nature, cover most of the common
causes of accidents.
(5) Once the equipment is isolated, precautions
must be taken to guard against accidental re-
12-2. Equipment isolation.
energization. Attach to the operating handles of the
open disconnecting devices padlocks (fig 12-1)
As a general rule, no electrical apparatus should be
and/or approved red safety tags (fig 12-2). Red tags
worked on while it is energized. If it is not known


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