2.
especially those precautions regarding electrical
safety.
Responsibilities
concerning
nonelectrical
ratings. As an ET1 or ETC, you will
automatically be considered an expert on
electrical safety precautions. Therefore, you
have a responsibility to educate the personnel
whose primary duties are nonelectrical about
these precautions. The responsibilities in this
area are ever increasing, as more and more
electronic equipment is used in the various jobs
aboard ship.
3. Responsibilities as a petty officer. In this area
you have the same responsibilities as all other
petty officers in enforcing all safety precautions.
Any failure to follow electrical safety rules or
procedures may result in mild to severe shocks. In some
cases, death may result. Nearly all shipboard electrical
shocks are caused in one or more of the following ways:
1.
2.
3.
4.
Unauthorized use of, or unauthorized modifi-
cations to, equipment
Failure to observe applicable safety precautions
in the use of equipment or in working on or near
energized equipment
Failure to repair equipment that was known to
be defective and had previously given users a
mild shock
Failure to test and inspect equipment for defects,
or failure to remedy all defects found by tests
and inspections
All of these failures maybe summarized as failure
to observe applicable safety precautions.
SAFETY EDUCATION
You cannot expect individuals to observe a
precaution unless he or she is fully aware of the dangers
involved. One of your first duties, therefore, will be to
ensure that all personnel in the electronics division are
aware of the dangers and the safety precautions
necessary to combat these dangers.
Safety precautions depend to some extent upon the
type of ship involved. Ships such as AOs and AEs
necessarily have some precautions that must be strictly
observed but which are not applicable to other types of
ships. Therefore, you should ensure that all personnel
read and understand all safety precautions pertaining to
the electrical and electronic equipment on your own
ship.
Safety precautions for personnel in nonelectrical
ratings should include information concerning electrical
shock and precautions these personnel must observe
when using electrical equipment aboard ship.
Facts to be brought out and points to be stressed to
the nonelectrical rating personnel concerning electric
shock should include the following:
1. Voltages as low as 30 volts can be dangerous.
2. The dangers from electric shock are much
greater aboard ship than ashore.
3. There is little middle ground between a slight
tingle and a fatal shock.
Fundamentally, current rather than voltage is the
criterion of shock intensity. The passage of even a very
small current through a vital part of the human body may
cause death. The voltage necessary to produce the fatal
current depends on factors such as the resistance of the
body, contact conditions, and the path the current takes
through the body. The probable effects of shock are
shown in the following table.
AC 60Hz
DC
(mA)
(mA)
0-1
0-4
1 -4
4-15
4-21
15-80
21-40
80-160
40-100
160-300
Over 100
Over 300
Effects
Perception
Surprise
Reflex action
Muscular inhibition
Respiratory block
Death
It is imperative to recognize that the resistance of
the human body cannot be relied upon to prevent a fatal
shock from 115 volts or even lower voltages–fatalities
from as low as 30 volts have been recorded. Tests have
shown that body resistance under unfavorable con-
ditions may be as low as 300 ohms and possibly as low
as 100 ohms from temple to temple if the skin is broken.
Volt for volt, dc potentials are normally not as dangerous
as ac potentials. This is shown by the fact that reasonably
safe “let-go currents” for 60-Hz ac are 9.0 mA for men
and 6.0 mA for women, while the corresponding values
for dc are 62.0 mA for men and 41.0 mA for women.
The instruction to personnel in nonelectrical ratings
regarding the safety precautions they must observe
2-24
