Shield wire

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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.

Terry Zank

About Terry Zank

Terry Zank is a contributor to The Wire and senior publications coordinator at OPPD.

One thought on “Shield wire”

  1. Just as a note, many of the shield wires on 161 kv and 345 kv transmission lines have multiple optical fibers integrated internally. These optical fibers provide for enormous bandwidth infrastructure for The District’s telecommunications systems.

    Thank you Terry.

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