Monday, February 4, 2008

Lineman for the County

What happened when the tree touched the power line? It was a shocking experience!!

While many people establish shelterbelts to increase crop yield, reduce home heating costs and to provide habitat for birds and mammals, it is important to consider the proximity of overhead power lines before planting the first tree.

Since most rural overhead lines are not insulated, any conductive material that touches the wire will cause a short circuit from the line to the ground resulting in a brief intense discharge of power that can fatal to bystanders in the vicinity. While most of the electric company awareness campaign is directed at farmers moving tall farm machinery such as augers and implements, it is actually trees planted too close the power lines that cause most electrical disruptions. As surprising as it make seems, trees that grow into power lines cause more than 70,000 hours of outage per year

Although some high voltage wires can be as much as 50 feet above the ground, most rural service is carried on poles that rarely exceed 25 feet in height, making them easily reachable by most trees grown in north central Alberta, such as poplar spruce and pine.

To make matters worse, on rainy or extremely humid days, the tree does not actually have to touch the line to initiate electrical transfer. During conditions of high relative humidity, the electricity can actually arc over a distance of several feet from the line to the conductor in a similar fashion as an arc welder.

Therefore it is imperative that there is a minimum of four feet of daylight between the ultimate height of planted and the overhead line

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