|
| |
Installation and Repair: Using Tools
|
|
 |
Electrical
employees use a variety of tools, such as nut drivers, conduit
benders, electric drills, and pliers. For more information
about tools with ergonomic advantages, visit the
tool
index.
|
|
|
|
| Hand Tools |
Potential Hazards:
 |
Figure 1
Wire clipper rubbing the palm.
|
 |
Figure 2
Wide handle spans and finger positions require additional force exertion to perform a task.
|
 |
Figure
3
Power drill.
|
 |
Figure 4
Bent-handled
tool.
|
-
Poorly designed or improperly used hand tools
may require excessive force and cause
awkward postures
resulting in tendonitis in hands, wrists
and elbows.
-
Short handles may press
or rub against the palm and
fingers (Figure 1) causing
contact
stress. Small handle diameter may
increase force requirements of tool leading to fatigue,
discomfort and pain.
-
Tools with wide handle spans require
extended thumb and finger positions (Figure 2) to activate the tool. These
postures require increased finger force to
provide adequate activation force increasing
fatigue, discomfort and pain.
- Improper orientation of the tool handle may
result in awkward position of the hand,
wrist, or arm and increase force requirements of the task.
Possible Solutions:
- Use
power tools (Figure 3) to do the job when repetitive or prolonged
force exertion is required.
-
Use a properly designed tool to promote neutral
posture of the wrist and hand. (Figure 4).
Generally, an
inline tool is best
on horizontal surfaces at about waist
height, and a
pistol grip is
preferable for vertical surfaces
at about waist height.
Bent-handled tools
can be designed to accommodate differing
work positions and angles.
- Use tools with padded grips and handles that
extend across the whole palm of the hand to
minimize contact pressure.
- Ensure that tools such as screwdrivers have
appropriately sized and shaped handles.
Generally,
handles should be about 1 1/2 inches to 3 inches in diameter.
Triangular handles with rounded edges provide a better grip.
- Use tools that do not require an extended
grip. The hand should be in the shape of a "C"
while gripping the tool. A span of 2 1/2 to
3 1/2 inches is best.
-
Ergonomic Design for People at Work, Volume 2.
Eastman Kodak Company, (1986).
- Replace tools if handles are damaged.
- Take regular breaks and
rotate tasks
when using a hand tool for an extended
period of time.
- Use
fitted gloves
which protect the hands from contact stress.
-
Keep tools well maintained and in good repair.
- A Guide to Selecting Non-Powered Hand Tools [1 MB PDF, 20 pages]. US
Department of Health and Human Services (DHHS),
National Institute for Occupational Safety and
Health (NIOSH) and California Occupational
Safety and Health Administration (Cal/OSHA),
(2004, August).
|
| Portable Power Tools |
Potential Hazards:
 |
Figure 5
A heavy pipe threader.
|
- Some portable power tools, such as pipe threaders
(Figure 5), may be heavy or require extreme
effort to counteract torque forces. Sustained
use of these tools puts stress on the back,
hands, arms, and shoulders.
- Tools such as jack hammers or large saws
that transmit
vibration may cause hand-arm vibration syndrome (HAVS). Early signs of HAVS are feelings of numbness or tingling in the fingers, hands, or arms, or numbness and whiteness in the tips of fingers when exposed to cold.
- When using tools employees may assume awkward postures including
bending, stooping or extended reaching.
Awkward postures maintained for long periods of time may cause
fatigue, discomfort and pain, especially when heavy tools are used.
- Improper orientation of tool handles may
cause
awkward
position of the hand,
wrist, or
arm and increase force requirements of the task.
- Repeatedly using a single finger to activate triggers on power tools
may cause overuse of tendons and muscles leading to irritation,
swelling, pain and eventually immobility.
Possible Solutions:
 |
Figure 6
Drill
with
torque
bar.
|
 |
Figure 7
Vice mounted on a three-legged stand.
|
-
Use tools with a proper handle orientation that allows
neutral wrist position. Generally, use tools
with a
pistol
grip
for vertical surfaces and an
in-line grip for horizontal surfaces.
- Use torque bars (Figure 6) on tools such
as drills or pipe threaders to minimize
the exertion required to control the tool.
- Use trigger-levers on power tools. These have a longer trigger to accommodate
three fingers, rather than those with single
finger trigger action.
- Maintain equipment and tools in proper working order. Unbalanced rotating parts or poorly sharpened cutting tools
may create excessive vibration and increase force requirements
when in use.
- Support the weight of heavy tools
(Figure 7) by using overhead
or under-tool supports.
- Avoid older power tools that were not designed
with ergonomics in mind and may vibrate
excessively. Consider reduced-vibration tools
when making new tool selection.
- Wear proper anti-vibration gloves when using power
tools and use only as much finger force as
necessary to provide proper control of the
tool.
-
Learn proper tool usage and safety practices. Employees should allow the tool or machine to do the work and should arrange the work so
that they can stand upright and use the tool with the elbows close to the body.
- Keep hands warm and dry.
- Use platform ladders, regular
ladders or
lifts to reach higher work areas so that arms may be
kept closer to the body. The arms may then safely support tools when in the
power
zone.
- Wear kneepads when kneeling is required.
- To reduce crouching and kneeling, sit on a stool
while working on lower areas.
- Minimize the time of continuous use when
operating a vibrating tool. Appropriate
operating times will vary depend on the
magnitude of vibration, however limiting
sessions to 10 to 15 minute of continuous
use with no more than 2 hours of total
operating time per day is generally
recognized as a prudent work/rest
schedule. Other means of dampening or
reducing vibration should still be observed
even during shortened sessions.
- Keep cutting surfaces of tools sharp and lubricated.
|
| Tool Belts |
Potential
Hazards:
 |
Figure
8
Tool bag on a tool belt.
|
 |
Figure 9
Tools placed on a hand truck.
|
-
Loaded tool belts may weigh over 50 pounds
(Figure
8), causing an increased load and contact stress on the lower back and hips.
- Suspenders used to hold the tool belt may cause shoulder
contact stress and discomfort.
- Wearing a tool belt for an extended
period of time may cause fatigue, discomfort and pain.
Possible Solutions:
- Use mobile tool box or bucket-style tool bag (Figure 9) instead of a tool belt.
- Use
padded
belts and suspenders to evenly distribute
the weight between the shoulders and the waist, thus reducing
contact stress.
- Arrange tools in bags so that their weight is distributed evenly.
- When possible, reduce the weight of the tool
belt by reducing the number of tools carried
to those necessary for the task.
- Use a backpack-style tool bag to distribute the weight of
tools over the body and improve posture if
tools must be carried for extended
distances.
|
| Bending and Cutting Conduit |
Potential Hazards:
 |
Figure 10
Manual conduit bender.
|
 |
Figure 11
Mechanical conduit bender.
|
 |
Figure 12
Flexible conduit.
|
-
Manual conduit bending (Figure 10) may
require exertion of significant forces and awkward
postures which may lead to overexertion of the back and shoulders.
- Bending over to cut conduit may result in
overexertion to the back and shoulders.
Possible Solutions:
- Use mechanical conduit benders (Figure 11),
especially on conduit with a diameter larger
than 1 1/2 inches.
- Where conditions are not optimal
and power equipment may not be available, prefabricate as much conduit as possible to minimize on-site bending.
- Where manual benders are required, use longer handles
thus increasing leverage and minimizes the amount of
force required to bend conduit.
- Place conduit in a vice or fixture to maintain stability when cutting. Support conduit on a table or sawhorse.
- Wear
gloves when manually bending conduit to reduce contact
stress and avoid cuts. Ensure that conduit
ends are properly reamed and good
handles are maintained on manual conduit benders.
-
Where
code
allows,
use lightweight, flexible conduit (Figure
12)
which does not require
bending.
|
| Drilling Holes |
Potential
Hazards:
- Hole saws and drill bits may get stuck while spinning resulting
in strong kickback and increasing the potential of severe injuries
to the wrists, elbows and shoulders.
- Drills must be used frequently on floors, floor joists or
rafters forcing employees to bend or reach for a work piece.
- Supporting heavy drills for extended periods of time may cause
fatigue, discomfort and pain.
- Regular exposure to vibration when using hand-held power tools
may cause hand-arm vibration syndrome (HAVS).
|
Figure 13
Drilling a hole.
|
Possible Solutions:
|
|
- Use an angle drill for large holes. This provides a longer lever arm to control torque forces
(Figure 13).
- Use a torque bar to help absorb the shock of a stuck bit.
- Use drilling tools with a built-in
kickback clutch.
- Do not force the bit. Apply even pressure
and let the drill do the work.
- Use bit extensions to help minimize reaching.
- Use platform ladders, regular
ladders
(Figure 14) or
lifts
to reach higher work areas so that arms may be kept
closer to the body. The arms may then safely support tools when in the
power
zone.
|
Figure 14
Fiberglass ladder. |
- Ask builders to use materials that do not
require drilling, such as engineered wood products
with knockouts.
- Ask builders to use spacers while laying fresh concrete to
minimize drilling after concrete has cured.
- Ensure that tool bits are sharp before using. Replace or sharpen
bits frequently.
- Use a stool to improve access and minimize reaching.
- Wear kneepads when frequent or prolonged kneeling is required.
|
|
|
|
Accessibility Assistance: Contact the OSHA Directorate of Technical Support and Emergency Management at 202-693-2300 for assistance accessing PDF materials.
|
Newsletter
RSS Feeds
