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CONN-OSHA Quarterly
May, 2010
Volume No. 60
May 2010
What is the most misused tool in a tool
box?
By Jeff Carter-Occupational Safety Consultant
After the last cup of Saturday morning coffee you
decide you can’t put off painting the door any longer. It’s easier to paint it
off the jam so you reach into your tool box for a slotted No. 8 screwdriver and
a 16 ounce hammer. With numerous blows from the hammer you use the screw driver
to drive the pins from the hinges and lay the door on saw horses. The hinge
plates were painted filling the screw slots with paint. Not to worry. Again,
with the aid of the hammer and screw driver you clean the paint from the slots
of nine No. 10 screws. The paint can lid is liberated from the can with the
screwdriver and without a stick in sight the same tool is used to stir the
paint. Knowing the value of a good tool, you wipe the screw driver clean of wet
paint.
Is there any wonder when you try to drive the nine No.
10 screws with the No. 8 screwdriver it slips from the slot and buries itself in
the palm of the hand? Being criticized for scratching the newly painted door is
almost as painful.
1910.242, the general requirements for hand and
portable powered tools and equipment states, in part, it is the employer’s
responsibility for the safe condition of tools and equipment, including those
furnished by employees. This requirement includes the condition of the above
mentioned screw driver, as well as the split handle of a hammer or the worn jaws
of a pipe wrench that may slip and cause an employee to loose balance and fall
from a step ladder.
The shop compressor usually delivers between 120 to
140 pounds per square inch (PSI) to operate equipment or tools used in the shop,
but compressed air used for cleaning must be reduced to 30 PSI. High air
pressures can deliver particulate such as chips with enough force to imbed in
the eyes or
 lift
skin off a person if directed toward an open wound. In fact, cleaning with air
is effective due to the volume and speed of the air and not the pressure. A leaf
blower used to clean lawns in the fall delivers a large quantity of fast moving
air, at just over atmospheric pressure, and is effective enough to blow all the
oak leaves into piles. Air pressure can be reduced by regulating it to 30 PSI or
by purchasing specifically designed air guns. These guns are sometimes embossed
with words such as “30 PSI Max” or some styles of guns can be externally
identified by radically drilled holes in the nozzle. The holes allow air to
bleed off should the nozzle come in contact with the body. Beware of taped off
holes or nozzles replaced with fittings to allow for extended reach.
Portable circular saws with a blade greater than 2 inches must have the blade
guarded above and below the shoe. The lower guard must be self adjusting as the
saw is pushed through the material and once through, return automatically and
instantly to cover the lower portion of the blade. The saw also needs a constant
pressure switch requiring finger pressure to close the switch, and once finger
pressure is removed the switch must open shutting off the saw. Gasoline powered
chain saws require the same operating means. Powered hand tools such as drills,
tappers, fastener drivers, horizontal, vertical and angle grinders with discs
greater than 2 inches, and saws without spinning blades; reciprocating, saber,
scroll and jig saws must have a constant pressure switch but may be equipped
with a lock-on device as long as the device can be disengaged with one motion of
the same finger that turned it on.
1910.304(g)(6)(vi)(C)(3) requires all hand-held
motor-operated tools to have the noncurrent-carrying metal parts grounded. These
tools can be identified by a 3-prong plug with the equipment grounding conductor
attached to the metal housing of the tool. The equipment grounding conductor is
needed to conduct fault current back to the breaker and open the breaker
stopping the flow of current.
Thermal magnetic circuit breakers are found in most
distribution centers (breaker boxes). They incorporate an electromagnet which
responds instantaneously to large surges in current (short circuits) and a
bimetallic strip responding to less extreme but longer-term over-current
conditions. The circuit breaker contacts are held closed by a mechanical latch.
If there is a short circuit, such as insulation break
down on the ungrounded current carrying conductor (hot wire) the hot wire can
come in contact with the tool’s metal housing. This creates minimal resistance
in the circuit, resulting in a large amount of current flowing through the
equipment grounding conductor. The pulling force of the magnet increases
proportionally with the current flow. As the current in the electromagnet
increases beyond the rating of the circuit breaker, the electromagnet’s pull
overcomes the spring tension. This releases the latch thereby opening the
contacts and stopping the flow of current. Circuit breakers are designed to open
if an over current of 5 times its handle rating occurs. For a 20 amp breaker,
100 amps are required to open a breaker instantaneously due to a short circuit.
“Instantaneously” is defined as one-tenth of a second.
1910.304(g)(5) requires a permanent, continuous and
effective path to ground for this reason. Loose connections, broken wires,
grounding through the yokes of a duplex outlet in an armored cable installation,
or loose or corroded fittings and conduit in an EMT installation may not have
the ampacity to flow 5 times the handle rating of fault current.
If the tool has a worn drive train, improperly
lubricated bearings, if you are cutting through unusually tough material or the
bit or saw blade is dull, the tool may become over-loaded. In this case the
breaker could open due to less extreme
 but
longer-term over-current conditions. As current flows through the bimetallic
strip a small amount of heat is produced. As the current increases so does the
heat. The bimetallic strip, composed of two different metals bonded together
will expand, but at different rates causing the strip to bend. The strip is
attached to a series of levers and latches. When the strip moves the lever far
enough it unlocks the spring loaded handle opening the electrical contacts and
stopping the current flow.
The only alternative to an equipment grounding
conductor is double insulation. Double insulated tools are designed by
electrically insulating all current carrying parts form the outer housing.
Additional design features include a switch to break the ungrounded current
carrying conductor, or the black or hot wire. Because these tools do not have
polarized plugs, a double pole switch is utilized to open both conductors
simultaneously.
Generally, portable grinding wheels are guarded unless
they are 2 inches or smaller in diameter, are cone, plug, or threaded hole pot
balls, or if the wheel is used for internal work and the work offers protection.
Internal work does not mean a welder inside a vessel using an angle grinder
grinding out the root pass of the weld. In this case the worker is not protected
from an exploding wheel. The guard must protect the spindle end, nut and outer
flange unless depressed center grinding wheels such as Type 6, 11, 27 and 28 are
used, or where the work provides a suitable measure of protection. Regardless of
specific guarding requirements, the employer’s hazard assessment required by
1910.132(d) should require the use of eye protection.
A Powder-actuated tool, often called a "Hilti" or
"Ramset" is a nail gun used in construction and manufacturing to join materials
to hard substrates such as steel and concrete.
Powder-actuated technology was developed during the
Second World War when high velocity fastening systems were used to temporarily
repair damage to ships. In the case of hull breach, these tools fastened steel
plates over damaged areas.
Powder-actuated tools come in either low velocity or
high velocity types. Low velocity tools introduce a piston into the chamber. The
propellant acts on the piston, which then drives the fastener into the
substrate. A powder-actuated tool is considered low velocity if the average test
velocity of the fastener does not exceed 492 feet per second. In high velocity
tools the propellant acts directly on the fastener. Although high velocity tools
may not be made or sold in the United States, some are still used in
shipbuilding.
Operators and assistants must wear eye protection.
Head and face protection is used based on working conditions.
On low velocity tools, spall shields shall be provided
by the manufacturer. The tool will be designed to prevent accidental discharge
and require two separate and distinct operations by the operator to fire the
tool. The power of the tool can be varied generally by choosing loads of
increasing power identified by color coding. The color coding is standardized
throughout the industry.
Low velocity tool load are limited to 300 feet per
second fastener speed measured at 6.5 feet from the muzzle.
Before and during use the operator must inspect the
tool, and if found defective, cease to use it. Tools are not loaded until use,
and shall not be unattended while loaded. In case of a misfire the tool must be
held in the operating position for 30 seconds or more should there be a delayed
firing. Do not fire into very brittle or soft materials, or closer than 3 inches
from the edge of the material as it may break away from the material and
ricochet. Do not attempt to fire into spalled material caused by an unsuccessful
fastening. Never use this tool in an explosive or flammable atmosphere.
So, what is the most misused tool in your tool box?
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CONN-OSHA has a new Consultation Manager
... James H. Pierce
James joined the State of Connecticut Department of
Labor Division of Occupational Safety and Health (CONN-OSHA) family in 1992 as
an occupational hygienist and for 18 years he served both the private sector and
the pubic sector as an industrial hygienist. In addition to his duties as an
Occupational Health Consultant, James has represented CONN-OSHA in various
endeavors that involved other state agencies such as the Connecticut Department
of Environmental Protection, the Connecticut Department of Public Health,
Homeland Security, and the Connecticut Department of Agriculture.
He received a Bachelor’s Degree majoring in
environmental biology with a minor in chemistry from Eastern Connecticut State
University.
In his new position, James will act as the private
sector consultation manager We congratulate him on his promotion, it is well
deserved.
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OSHA QUICK CARD
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Hazard Corner ... A Power Drill CAN Kill
Ellen Burgum, Occupational Safety Officer
A young father of two was working on HVAC equipment
one night when he was fatally electrocuted by a faulty power drill. The
hazardous condition could not be seen; it was hidden within the metal c asing
of the Craftsman electric drill. During the fatality investigation, close
examination discovered the hazardous condition. The metal encased Craftsman
drill had been modified with a 19-foot replacement cord with a two-prong plug.
Inside the drill, a frayed bare wire was against the metal casing. The metal
casing became energized and, without an equipment ground in place, the
electricity followed the path of least resistance to ground. The electrical
current entered the worker’s hand and came out his foot to meet the ground on
which he stood.
What went wrong? The replacement of the cord and plug!
This change, which was unknown to the HVAC worker, left the power tool without
an equipment ground. Had this power tool been equipped with an equipment ground,
this father would have gone home to his two young children that night.
There are still old drills with metal housing and
original cords in use. When they were made, manufacturers were not required to
provide an equipment ground, so they will have a two-prong plug. While that
two-prong will fit into a grounded polarized outlet, the hazard is still there.
Discard them: the risk to your or someone else’s life is too great.
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Training Update
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Safe Driving May 25, 2010.
The goal of this session is to increase awareness of the need for and the
benefits of safe driving. The focus of this session will be on the four
skills that experts feel have the most promise of preventing crashes if
implemented. This class will be held from 10:00 am—12 noon.
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Trenching & Excavation Safety
May 27, 2010. This workshop will provide an overview of 29 CFR
1926.650-652 excavations, including the role of the competent person. The
session is designed to assist participants in identifying hazards associated
with excavations and related activities. This class will be held from
10am-12 noon.
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Powered Industrial Trucks July
13, 2010. This workshop includes the basic requirements of the OSHA 29
CFR 1910.178 Powered Industrial Truck Standard which affects both General
Industry and Construction material handling operations. This class will be
held from 10 am-12 noon.
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Construction Site Safety July
30, 2010. Construction managers, first line supervisors, and
construction employees will be provided with an overview of four areas of
concern on the construction site. Program contents include: fall protection,
scaffolding and ladders, electrical hazards, and trenching safety. This
class will be held from 9:00 am - 12 noon.
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Breakfast Roundtable. This
discussion group meets the third Tuesday of every month from 8:15 am to 9:45
am. Pre-registration is required. To be placed on the e-mail distribution
list, contact John Able at
able.john@dol.gov
Classes are free and held at 200 Folly Brook
Boulevard, Wethersfield, CT in Conference Room A/B. To register, contact John
Able at able.john@dol.gov or Catherine
Zinsser at zinsser.catherine@dol.gov.
Pre-registration is required. A Photo I.D. is required to allow entry into a
public building. For more training information, visit the CONN-OSHA web site
www.ctdol.state.ct.us/osha/osha.htm
Fatality & Casualty
Reporting:
Connecticut Department of Labor - OSHA
38 Wolcott Hill Road
Wethersfield, CT 06109 |
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You may also reach us by phone at (860) 263-6900 or visit our website at
www.ctdol.state.ct.us/osha/osha.htm. |
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Last
Updated:
April 17, 2018
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