Robin Furrer, Vice President, Transmission Field Services: I'm Robin Furrer, vice president
for transmission field services at the Bonneville Power Administration. Since June of 2007,
BPA has been working to meet new mandatory vegetation management standards issued by
the North American Electric Reliability Corporation to ensure that transmission of electricity
to your local utility is not disrupted by trees or high brush. In many cases, meeting
this standard means we must remove trees that grow in and around the rights of way along
which are power lines run.
But meeting these standards is not the only challenge trees and high pressure present.
As you’ll see in this video, trees and power can be a dangerous and sometimes lethal combination.
Removing these dangers trees is also about ensuring your safety and the well being of
your property. It’s also about ensuring that trees and other vegetation around power
lines don’t cause outages that leave critical public safety functions without power. In
the end, we hope this video provides you with a better understanding of our vegetation management
program and the methods we are using to meet the challenges presented by trees and high
brush around high voltage power lines.
Doug Johnson, Public Affairs Specialist: The power lines that BPA uses to transmit electricity
to customers throughout the Northwest are un-insulated braided aluminum. Now when these
lines get incredibly hot because the temperature is between 90 and 100 degrees outside, they
can sag down a great deal. When you couple that with the fact that there’s a lot of
high vegetation and tall trees in this area, you have a recipe for disaster —because
these trees can touch these lines. And even if they don’t, the power can leave these
lines can go into a tree or a piece of high brush if it gets close enough. Now when you
consider the fact that the electricity that it takes to light a ten watt bulb is enough
to kill you, you can only imagine what happens when the electricity leaves these lines and
gets into a tree. Anything along the path or around this tree for that electricity get
into –humans, livestock and pets – can be subject to serious injury or death if this
occurs.
(Video from tree-contact incidents in the Northwest)
(Graphic: Why keep the rights of way clear? To maintain reliability; ensure public safety
and prevent damage to land and property)
Ben Tilley, Natural Resource Specialist: Electrical current is always looking for a path to ground.
And it will use any path it can to get there. Trees and other objects tend to be the most
common paths that electricity uses to get to ground. A tree does not have to actually
touch the conductor to find a path to ground. It can actually jump or flash over to that
piece of vegetation or other object and make its way to ground through that path. Once
the electrical current gets to ground, the issue we have at that point we call step and
touch potential. If you can imagine throwing a rock into a still pond and watching the
ripples that result from that rock hitting the pond; electrical current acts in the same
manner across the ground. And anything that’s in that path or in that rippled area, a house,
a human being, an animal, could potentially be exposing themselves to serious injury or
even death.
Doug Johnson: To keep you and your property safe and ensure that we don’t experience
unplanned outages because trees and vegetation gets too close to or comes in contact with
power lines, BPA’s determined that there needs to be a 25-foot buffer between power
lines and the trees and high brush that grow around those power lines. It’s also important
to note that that 25-foot buffer needs to be between the maximum that a tree or a piece
of brush or bush can grow up or in to the power lines.
(Graphic: BPA’s power line safety zone: 25-foot safety zone between power lines and
the mature potential growth of trees and other vegetation)
Doug Johnson: We hope the information presented in this video provides you with a better understanding
of the dangers that exist when trees and other vegetation get too close to come in contact
with high voltage power lines. If you’d like more information or would like to talk
to someone from BPA, please contact us.
(Text: If you have any questions about our vegetation management program or would like
to request a BPA Land Use Application, call us at (800) 836-6619. For more details on
BPA rights-of-way and how to stay safe around high-voltage power lines, visit our
Web site at: www.bpa.gov/corporate/pubs).