, Derry, New Hampshire

May 16, 2013

Utility inspects lines from copters

Derry News

---- — National Grid has started its semi-annual aerial inspections of more than 2,900 miles of high-voltage transmission lines in Massachusetts, Rhode Island, New Hampshire and Vermont.

The helicopter flyovers will identify and address potential problems in the transmission lines before they impact electric service for customers. These aerial inspections complement the regularly-conducted, ground-level inspections by quickly and efficiently covering National Grid’s transmission system, even across rugged and isolated terrain.

Transmission lines are generally defined as high-voltage lines carrying electricity at or greater than 69,000 volts. They typically deliver power from generating plants to local electric companies who in turn serve their customers.

The helicopter inspections are conducted by experienced trained personnel using high-powered gyroscopic binoculars. They are particularly interested in signs of wear on power line conductors and lightning protection devices; damaged or leaning transmission structures; loose or broken guy wires; broken, chipped or cracked insulator equipment; and trees leaning toward the lines or into the transmission corridors.

In addition to damaged lines, towers or trees, the flights are conducted to identify signs of waste disposal or unauthorized construction on the rights of way. These could alter the amount of clearance between the ground and the power lines and might lead to human contact with the lines that could result in severe injuries or vegetation interference that could lead to power outages. Of additional concern are signs of erosion, which may cause the transmission structures to become unstable.

The inspections are expected to take approximately five weeks to complete, weather permitting. Flight schedules and routes may be changed on short notice due to regional weather conditions. Public safety officials in the communities over which the flights pass are notified of flight patterns. Visit