DIGGING SAFELY
Power Line
Safety for
Excavators
b y
C h u c k
J e n s e n
I
t’s not a secret that power lines, and the electrical current they carry, don’t care if you have a family, a deadline, or a fishing trip planned
for the weekend. Yet every year, nationwide, thousands of unintended contacts are made with power lines. The reasons vary, as do the
results which range from damage to death. The question you have to ask yourself is, “Do you want to roll the dice with your life or the life
of one of your employees?”
It’s important to remember how electricity works. Electricity has a single-minded goal and that is to go to the ground through every available
path. How much goes through any single path depends on how conductive the circuit is. So, to simplify things, remember that the human
body is made up of mostly water and water is an excellent conductor of electricity. You simply don’t want to give electricity a chance to take
a path to ground through your body.
While being a necessary part of our everyday lives, electricity can be an indiscriminant killer. Typical distribution power lines carry 7,200
volts per phase (wire) from the substation to the transformer, and up to 240 volts from the transformer to the typical home.
In terms of amperage, which is what really causes the damage to your body and organs if caught in an electrical circuit, a typical single family
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home has a 100 amp service. It’s widely accepted
that only 30-50 milliamps are needed to interrupt the rhythm of your heart and stop it from
functioning properly. Any electric line you hit
has the current to harm or kill you.
The annual DIRT “hit” data doesn’t reflect the
“near misses” or “almost hits” because excavators often don’t know how close they came
to coming into contact with a buried power
line. It’s downright difficult to see the leading
edge of a form pin, ground rod, boring rig, or
even a shovel. So it’s entirely valid to say there
are a significantly larger number of damages
Cover-up on an overhead
electric line provides
greater visibility for
excavators.
than what is reported for actual “hits”. On a
monthly basis our crews find and fix nicks on
buried power lines where the above mentioned
objects damaged insulation or cable jacket, but
missed the current carrying wire. Even a slight
nick to cable insulation will likely cause it to
fail over time. The facility owner should be
notified if this happens – most utilities won’t
charge for fixing this because it’s a simple insulation patch at that point, not a time consuming and costly splice or cable
replacement.
Changing gears a bit, overhead power lines often get
lost in the excavation conversation because they are
an “obvious” hazard. Our
experience is there is nothing obvious about them when
employees don’t receive training about the hazards of overhead lines.
There are specific laws that are written into
OSHA’s standards due to those hazards, such
as staying at a minimum of 10 feet from any
overhead power line. The cable on a crane makes
a great path to ground, as does a track hoe,
backhoe, ladder, or any other
metal equipment that comes in
contact with the line. There are
specific OSHA requirements
for safe distances when working
around overhead power lines
with cranes.
So the question that follows
all of this is, “What can I do?”
The better question is, “What
should I do?” Keep in mind it
will most likely be you that has to knock on the
door of an employee’s home and explain that
dad or mom won’t be coming home tonight.
First things first – use your local One Call
system. Always. Locates may be the only thing
that alert you and your employees to the presence of underground power lines. Use of the
One Call system will alert the electrical utility
of your operations, and you have the chance to
discuss with them whether the work may expose
employees to power line hazards. Most, if not all
utilities, given the opportunity, will work with
you to minimize the risk to your employees as
well as to their lines and equipment. We all have
the same simple goal in mind, the safe completion of the work. It’s a simple call to 811.
Second (and of equal importance), make the
time to train you employees about the hazards and safe excavation practices. A lot of
emphasis is put on gas pipelines and rightfully
so; but ignoring another potentially fatal hazard is not a good business practice. Most utilities and One Call systems have annual training
sessions free to all excavators.
Take advantage of them - and
don’t just send the foreman or
the office staff. The employees
who are putting the shovel in
the ground are the ones that
need the training the most.
Third, get involved. The
Common Ground Alliance
is an organization dedicated
to bringing utility operators
and excavators together at the
same table. Many states have
chapters and as an organization they are always
looking for new voices and fresh perspectives.
The opportunity to network is invaluable, and
hearing the reality of what every member has to
deal with develops insight you would otherwise
never get. That networking has
helped us solve problems in a
lunchroom instead a courtroom.
We typically see two “buckets”
of hits on electrical cable and
wire. The first bucket contains
underground hits. These fall into
several smaller buckets but most
often we see failure to call for locates, failure to expose the facility (cable), and failure to protect
the marks (which leads to hitting cable that was
clearly marked to start with). The biggest reason we hear why those things happen is “time”,
which is odd because it takes minutes to call in
a locate or consult the utility and hours, or even
days, to clear the scene of an accident.
The second bucket is overhead hits. Those also
have a great deal to do with time, but also with
human nature. Our minds can only manage so
many tasks, and that is accomplished through
“toggle tasking” (you can’t do multiple cognitively demanding tasks with the same amount
of concentration). So when that dump truck operator has to back in underneath a power line
while keeping an eye on the side view mirror,
he or she can only be expected to see so much.
When requested we specifically put “cover up”
out on our lines so that relatively small wire can
be seen that much better and provides a small
degree of “brush contact” insulation. Requesting
cover up, using a spotter, and doing a good prejob tailgate can minimize the chances that your
equipment doesn’t momentarily become part of
the power grid.
I have followed a safety principal that has helped
keep things in perspective through the years:
you can either pay for prevention or you can
pay for treatment. Which one would you rather
invest in? In almost every case I can recall, we
spent hours and days resolving situations that
could have been prevented in minutes, without
the emotional and physical harm our employees
have to deal with as a result of an injury. We owe
our employees, their families, and our customers our best efforts when it comes to excavation
safety and damage prevention – and it’s really
not that difficult when you compare the effort
to the consequences. Please Dig Safely. ESG
Chuck Jensen, CSP is Loss Control Manager
for Connexus Energy. He can be reached at
[email protected].
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