20 Arbor Age / September 2014 www.arborage.com
and create a tie-in position
that takes the potential for
swing into the conductors
— if a fall should occur —
into account.
Trees and the environ-
ment are unpredictable, and
this unpredictability is the
greatest threat to a worker.
Unexpected weights, de-
fects, and movements of
limbs from a gust of wind
can quickly create a haz-
ardous situation. Making
small, controllable cuts can
help workers manage tree
limbs and better anticipate
where they may fall, which
can lower the risk of a limb
landing on a live wire if it
goes the wrong way. The use
of ropes and other devices
can help workers safely move pieces to a landing zone on
the ground without contacting wires.
On any job site, tree workers should make sure they know
have a spotter on the ground
who, in addition to watching
for other dangers, is aware of
identifi ed electric lines and
their proximity to ongoing
work. All workers must know
and use clear communica-
tion signals for when to stop
working if danger is present.
The climber or bucket
operator should be aware
of the wires at all times and
where they are in relation to
their own bodies or equip-
ment. They also need to
consider not just their own
body and equipment posi-
tion, but the location of the
limbs and branches on which
they are working — and,
more important, whether
these branches might come
in contact with an electric line if they are cut and fall in
an unexpected direction. A climber should also climb on
the side of the tree opposite to conductors when possible,
SPECIAL FEATURE SPECIAL FEATURE
Step Potential: When an energized line makes contact with
ground the voltage dissipates in concentric circles away from
the initial contact point. "Step potential" is the voltage value
change from ring to ring. When a worker has his or her feet in
two different voltage zones, he or she is facing a "step potential
hazard" and can receive an electric shock.
