The Wire

Energy news from Omaha Public Power District

How Does That Work?

Shield wire

February 6, 2017 | Terry Zank | how does that work, safety, T&D
shield wires

WHAT IS IT? Shield wires are wires installed on all overhead transmission lines within OPPD’s electrical system to protect them from lightning. Transmission lines carry high voltages of electricity over long distances.

shield wires
A transmission tower with shield wires running along the top of the structure.

Many OPPD distribution lines (lower voltage lines that deliver power to homes and businesses) also have a “neutral” wire above the lines that serves as a shield wire.

OPPD normally installs uninsulated, non-energized shield wire above power lines to protect them from lightning strikes. Installers attach, or “ground,” the shield wire to each wood or metal pole on the line, with wire running down the poles to the ground.

Utilities typically install shield wire above power lines so that any lightning is more likely to strike the shield wire. For this reason, the shield wire is normally not insulated.

The shield wire is grounded at each pole. Any voltage surge from lightning safely and quickly travels to the ground. This prevents or minimizes damage to the power lines and equipment, and helps prevent power outages.

This also helps prevent lightning surges from continuing down a power line and possibly into a customer’s home or business.

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About Terry Zank

Terry Zank is a contributor to The Wire and senior digital channel specialist at OPPD, where he has worked for 30 years. He and his wife have three sons. Terry enjoys bike riding, playing racquetball, hiking, watching college football, watching great movies from years’ past, and citing quotes from those movies, much to his family’s chagrin.

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