October 2010

• Introduction
• Making the cut
• Other causes of Outages
• What you can do
• Why not bury all electric lines?
• Protecting habitat under power lines
• Download the full article as a

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Introduction

Trees may seem harmless on a calm, sunny day. But add a strong wind or ice accumulation on a stormy night, and trees may threaten your home’s electric supply.

“Most of our storm outages are related to trees contacting power lines,” says Tommy C. Greer, director of job training and safety for the North Carolina Association of Electric Cooperatives. “Regular trimming of trees and brush along power lines helps prevent the number of outages as well as blinks.”

Electricity interruptions can occur when branches break and fall across power lines, or when trees tumble onto power lines. When strong winds blow, limbs growing too close to power lines may sway and touch wires. These momentary power disruptions (called “blinks” or “blips”) can damage computers and other sensitive electronic equipment and leave digital clocks flashing. And then there’s arcing—when electricity uses a nearby tree as a path to the ground—which could spark a fire.
Your electric cooperative sends crews on a scheduled basis to clear growth away from power lines as a way of reducing potential outages and safety risks. As a rule of thumb, 25 feet of ground-to-sky clearance should be available on each side of utility poles to give power lines plenty of space.

Maintanence along power line rights of way has led to a drop in vegetation problems. For the first time ever, no outages were reported last year along transmission lines anywhere in the U.S., according to the North American Electric Reliability Corporation (NERC), which oversees reliability of the transmission system that blankets most of North America.