Spalling Prevention on Electric Poles

The majority of the world uses electric poles. Although most electric poles are on land, a few are in the ocean. The Florida Keys is a prime example of this. The islands need power, and in order for that power to make its way throughout the keys, electric poles must be placed in the ocean.

Electric poles placed in the water experience spalling at a faster rate than those out of water. Spalling is the breaking off of the concrete base of the electric pole. This is usually caused by the metal support structure inside rusting and expanding, causing the concrete to crack and break. Metal rusts much quicker in the presence of saltwater, which means spalling could occur more often on ocean electric poles. 

Worker welding connections. Photo Provided by Michael McKenney.

Since ocean electric poles experience spalling at an accelerated rate, a process called galvonic cathodic exchange is used to slow down the rusting process of the steel supports. Rust causes an electric current, so a zinc anode is used to draw the electric current away from the steel since it deteriorates slower than other metals. The process is typically a one-time solution, but if the zinc has deteriorated too much, more anode material can be added. 

This process has only started being applied to the electric poles near Key West recently. The poles did not have galvonic cathodic exchange done to them when they were first built. Third-Party Oversight Project Manager Michael McKenney said, “It [zinc anodes] can be installed when poles are first installed but often isn’t.” When questioned why this was, he pointed out that cost would be a primary factor. Budgets for the installation of the electric poles often exclude galvonic cathodic exchange because it doesn’t fit in the budget and is often unneeded until a few years after installation. 

Electricity is used almost everywhere, even on islands. The islands that are closer to the mainland, can often use power lines that are placed in water to get electricity from the mainland. The electric poles placed in the ocean often experience spalling faster than those on land.


Michael McKenney — Third Party Oversight Project Manager

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