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Supplemental Information: Ergonomic Principles Index
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This index includes many general ergonomic principles that apply to this eTool and smart practices that increase productivity and decrease ergonomic risks.
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Correct, neutral posture
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Postures
where the body is aligned
and balanced, while sitting
or standing. The head is
kept upright and is not
turned to either side more
than about 30 degrees or
tilted forward or backward
more than about 15 degrees.
When the worker is standing,
the torso is not bent more
than 10 to 20 degrees from
the vertical position and
the natural curves of the
spine are maintained. The
pelvis and shoulders should
face straight ahead to avoid
twisting the torso. The
shoulders are relaxed and
knees slightly bent. The
arms hang normally at the
side, with elbows close to
the body. The elbows are not
bent more than about 90
degrees and the palms face
in toward each other and the
center line of the body. The
wrists are in line with the
forearms and are not bent
sideways, forward (towards
the palm), or backward
(towards the back of the
hand.) When the worker is
seated, the buttocks and
feet are firmly supported.
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Housekeeping
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Establishing a strong housekeeping program will keep the work place tidy and reduce the risk of tripping over cords and debris. It also extends the life of tools and equipment, and results in increased productivity.
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Lifting |
Lifting properly is important. While there are some general lifting guidelines, a
different approach may be needed for each load to be lifted. Sometimes it is appropriate
to lift with the legs, and other times the back should be used to lift. These techniques
depend on the size and shape of the load, and the frequency of lifting that is required.
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Planning |
Planning should be done with ergonomics in mind. Items to be planned include determining
routes between staging areas and work spaces, scheduling for members of other trades,
and knowing what services and utilities will be provided.
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Power zone |
The power zone for lifting is close to the body, between mid-thigh and mid-chest height.
Comparable to the strike zone in baseball, this zone is where arms and back can lift the
most with the least amount of effort.
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Proper handholds |
Proper handholds make lifting easier and reduce the risk of injury. Handholds should be
made large enough to accommodate larger hands and should not dig into fingers and palms.
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Pulling vs. Pushing |
Pushing is generally preferable to pulling. Pushing allows the
employee to use large
muscle groups and apply more force to the load. Pulling carries a greater risk of
strain and injury.
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Staging |
Staging is an important step in any electrical project. Proper staging includes placing
materials as close as possible to work spaces, and storing materials at ideal heights
so employees can utilize the power zone to take materials from storage.
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Task Rotation |
Many stressors can not be
engineered out of a task,
short of complete
automation. Rotation of
assignments can be an
effective means of limiting
the amount of time employees
are exposed to these
stressors. This will often
reduce the chance of injury,
because the risk of injury
is proportional to the
amount of time one is
exposed to a stressor.
Caution: Rotation of
assignments should never be
used before significant
attempts to eliminate the
stressors have been
investigated. The job should
always be modified to expose
the employee to the least
amount of stress possible.
Analysis of the job is
essential, because moving an
employee between tasks that
affect the same part of the
body does not provide any
periods of rest.
Rotate to jobs that affect
different parts of the body
or have different
intensities.
Many tasks primarily affect
different parts of the body.
Some example are:
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Lifting a heavy load.
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Repeatedly bending generally
affects the low back.
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Reaching to access or to
place items in positions
that require the elbows to
be pulled away from the body
often affects the shoulder.
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Grabbing, turning, squeezing
or finger strikes can affect
the hand, wrist, and elbow.
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Looking down or to the side
repeatedly for a prolonged
time can affect the neck,
head, and shoulders.
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Tasks that require standing
for a long time can affect
the legs, feet, and back.
Rotation of employees
between tasks that affect
different parts of the body
allows employees to have
periods of rest and
recuperation while still
remaining on the job. An
example of a possible
rotation scheme might be to
move an employee who spends
most of the day attaching
fixtures or other overhead
task to a loading and
moving job where
the arms are down at their
sides. While on the
lifting task the hands,
shoulders and
arms can rest if the loads
lifted are not too large and
proper hand holds are
provided.
Work areas may have tasks of
differing intensities, such
as using #12 wire which
requires more force exertion
rather than using #14 wire
which is easier to bend.
Look for opportunities to
rotate between tasks that
are less intense and more
intense.
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