| In 1990, a water well driller was working
under a 12,000 volt overhead power line that was 36 feet above the
ground. The job consisted of the repair of a submersible pump for
a residence. With the mast of the drill rig raised, the driller removed
the pipe from the well, which came into contact with the power line.
The drill rig became energized, the driller provided a ground and
was electrocuted.
Each year an average of 15 electrocutions occur
through contact with overhead power lines with cranes or boomed
vehicles. The drilling industry is not immune to this exposure:
therefore, we should take notice of the findings of two government
agencies.
The National Institute for Occupational Safety and
Health (NIOSH) has found that electrocutions accounted for approximately
7% of all work related deaths during the period between 1980-1989.
Similarly, in a separate study, the Occupational Safety and Health
Administration (OSHA) found that 65% of the work related electrocutions
occurred in the construction industry and nearly 30% of these electrocutions
involved cranes.
OSHA's Requirements: Current
OSHA regulations require drillers to take precautions when their
drill rigs are operated near overhead power lines. These pre-cautions
require drillers to assure that overhead power lines are de-energized
or separated from the drill rig by implementing one or more of the
following procedures.
- De-energize and visibly ground electrical distribution
and transmission lines.
- Use independent insulated barriers to prevent
physical contact with the power lines.
- Maintain a minimum clearance between energized
power lines and the drill rig's boom. (At least 10 feet plus 0.4
inches for each kilovolt above 50 kilovolts or maintain twice
the length of the line insulator but never less than 10 feet.)
Where it is difficult for the driller to maintain
clearance by visual means, someone should be designated to observe
the clearance between the energized power lines and the drill rig.
The use of guards, insulating links, or proximity
warn- ing devices will not alter the need to follow required precautions.
These devices are not a substitute for de-energizing and grounding
lines or maintaining safe clearances.
Consider the following methods of limiting your
exposure to overhead power lines.
- Be cautious - operate the drill rig at a slower
than normal rate in the vicinity of power lines.
- Exercise caution near long spans of overhead
power lines, since wind can cause the power lines to sway laterally
and reduce the clearance be- tween the drill rig and the power
line.
- Mark the route the drill rigs must take in order
to safely travel beneath power lines.
- Never move the drill rig with the mast raised.
- Keep all personnel well away from the drill rig
whenever it is close to power lines.
- Prohibit persons from touching the drill rig
or its components until a signal person indicates that it is safe
to do so.
Notify Power Line Owners:
According to state laws, a one-call service should be
utilized. Many states require that at least two days' notice be
provided before they will visit the site. If you have noticed that
overhead power lines are in the vicinity of the site to be drilled,
notify the power line owner to de-energize the line. If this is
not possible, ask your client to relocate the drill site.
Evaluate Job Site: Thoroughly
evaluate job sites before beginning work to determine the safest
area for material storage, the best placement for drill rigs during
operation and the size and type of drill rigs to be used.
It is important to know the location and voltage
of all overhead power lines at the job site before operating or
working with any drill rig. If possible, meet with the client and
the utility company at the job site to discuss the best method of
protecting the drill crew.
In addition, do not operate the drill rig if a thunder
and lightning storm is in the area. In this case lower the boom
and wait for the storm to pass.
If contact occurs: To
protect against electrical shock injury in the event of contact
between a drill rig's mast and an energized line, consider the following.
- If you are able to understand what took place
during the electric shock, you are most likely safe where you
are and should stay put until you can assess the hazards.
- All personnel should keep away from the drill
rig, augers, ropes and pipes, since the ground around the machine
might be energized.
- The driller should not try to remove the drill
rig from contact by moving it in the reverse direction from that
which caused the contact. The driller should wait for help.
- If the drill rig is being driven and cannot be
moved away from contact, the driller or operator should remain
inside the cab of the truck until the lines have been de-energized.
Antennas: If
you are working in the vicinity of antennas, radar installations,
or microwave transmitters, the mast of the drill rig can become
thermally hot. Contact with the drill rig may cause burns. Therefore,
be aware of these types of hazards, and take proper precautions
to minimize your potential exposure.
Many times overhead power lines and antennas are
overlooked. The result can be disastrous. Keep in mind how, with
a little forethought, the dangers of working in the vicinity can
be significantly reduced. If there is ever any question regarding
such hazards, stop and determine the safest method before proceeding.
Your life may depend on it.
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