Prepared by Charles
V. Schwab, extension safety specialist, and Laura
Miller, extension communications.
Iowa State University Extension
Rain
clouds are moving in quickly and you want to finish harvesting
that last field. Another wagon is ready to dump, and more
will be arriving soon. You need to move the portable auger
to the next storage bin. To stay on schedule, you decide to
move the auger without first lowering the height. Without
warning, the auger contacts overhead power lines and two workers
are electrocuted. It was too late to do anything.
This
scenario is repeated on dozens of farms throughout the United
States each year. Electrocution is quick and deadly, killing
an estimated 62 agricultural workers every year. According
to the Iowa Department of Public Health, electrical hazards
caused three deaths and one injury on the farm in 1995.
The tragic
aspect is that these deaths could have been prevented. Farm
workers can reduce their risks of electrocution by knowing
how they, or others on the farm, can unknowingly come in contact
with electricity. This publication focuses on electrical hazards
posed by overhead power lines, standby generators, and general
operating procedures of electrical systems at the farm work
site.
The most
common risk of electrocution comes from overhead power lines.
Utility lines typically are not insulated, meaning that the
lines are bare. The lines may have been installed without
insulation, or the insulation may have been removed by exposure
to the elements.
Always
treat overhead power lines as if they were bare. Unlike birds
that rest on wires unharmed, humans often die when they touch
overhead lines because they contact the earth and wire at
the same time. This creates a channel for electricity and
electrocution can occur.
Many
types of farm equipment can come in contact with overhead
power lines. Tractors with front-end loaders, portable grain
augers, fold-up cultivators, and equipment with antennas easily
can become an electrical hazard and must be operated with
care.
Performance
of certain farm tasks also pose electrocution hazards. Always
use ladders with caution so that they do not come in contact
with overhead power lines. Harvest of tree crops or construction
also pose hazards.
Many
electrocutions occur near grain bins, and requirements in
the National Electrical Safety Code (NESC) address those dangers.
The Code requires raised power lines in dangerous locations
where tall equipment is used.
According
to the NESC, power lines must be at least 18 feet above the
highest point on any grain bin with which portable augers
or other portable filling equipment are used. The clearance
must be maintained a specified distance around the bin, and
sloped to meet the lower line clearance. If you are installing
new grain bins, contact a licensed electrician or power company
representative to help place electrical service lines. Lines
also can be buried to reduce risk of electrocution. Installation costs for overhead and underground power lines can vary;
contact local reps.
If you
have overhead power lines, ask local utility company officials
to help determine line height in each area of the farm. Never
measure line heights yourself! Once you know the height of
all power lines, you can determine the clearance needed for
equipment that must travel underneath the line. Try to maintain
at least a 10-ft. clearance between the power line and the
top of all equipment that must travel under it.
Consider
the possibility that some equipment during transport is actually
taller than when in use. For example, a large, 16-row planter
that folds up would be taller during transport than during
field use.
Busy
planting and harvest seasons may require temporary employees,
persons who may not be aware of potential dangers associated
with overhead power lines. Always remind additional workers
about overhead power lines. Give them special instructions
such as, "Never transport this cultivator through this
gate because of the overhead line."
Some
farms are equipped with a standby generator to provide emergency
power for essential farm operations during local power failures.
A key component of your operation's emergency power system
is the transfer switch, which removes the farm's electrical
system from the power company's utility lines.
The switch
prevents electricity generated by a farm operation's emergency
power system from entering the power company's utility lines,
and protects from electrocution those power company workers
who service lines during an outage. The switch also protects
your generator when power is restored.
Always
use the transfer switch whenever your standby generator is
in operation. Make sure all workers know the location of the
transfer switch.
Despite
operating precautions, equipment can come in contact with
electrical lines. It is important to know how to handle these
situations.
If your
tractor comes in contact with overhead power lines, stay on
the tractor. Ask someone to contact the local utility company
immediately to remove the danger. If there's an emergency,
such as an electrical fire, and you need to leave the equipment,
jump as far away from the equipment as possible. Do not
allow any part of your body to touch the equipment and the
ground at the same time.
Once
you get away from the equipment, never attempt to get back
on or even touch the equipment. Many electrocutions occur
when the operator dismounts and, realizing nothing has happened,
tries to get back on the equipment. The best way to handle
emergencies is by prevention. Respect electricity and avoid
contact with overhead lines.
Test
your knowledge about electrocution dangers with this quick
quiz.
1. Utility
lines are uninsulated wires, which means that wires are bare.
True or false?
2. A
transfer switch removes the farm electrical system from the
power company's utility lines. True or false?
3. Which
of the following pose electrocution hazards from overhead
power lines?
a) a
tractor pulling a fold-up cultivator
b) a
tractor with a raised front-end loader
c) transportation
of a portable grain auger
d) all
of the above
4. If
your tractor comes in contact with a power line you should
wait for help. True or false?
[Answers
to quiz: 1-True; 2-True; 3-d; 4-True]
- Apply
decals to all equipment that may pose electrical hazards
and explain decals to persons who work with the equipment.
- Inspect
farm equipment for transport height and determine clearance
with any power lines under which the equipment must pass.
- Review
the possibility of underground utility supplies for new
or replacement power lines.
- Determine
risks for potential electrical shock and restrict access
to that area.
- If
you have a standby power system, review its location, operation,
and importance with all workers.
This
publication covers only some aspects of electrical safety.
For more information, contact your Extension office, local
power company or cooperative, or write for this material:
- The
Agricultural Wiring Handbook, available from the National
Food and Energy Council (NFEC), Columbia, Missouri 65201.
Fee for publication.
- The
Farm Building Wiring Handbook, MWPS-28, available from the
Midwest Plan Service, Iowa State University Extension, Publications
Distribution, Ames, Iowa 50011. Fee for publication.
Disclaimer and Reproduction Information: Information in
NASD does not represent NIOSH policy. Information included
in NASD appears by permission of the author and/or copyright
holder. More
NASD Review: 04/2002
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