Power Lines Blog

Defending against outages: Squirrel tracker


By Alex Hofmann, Director, Energy & Environmental Services, American Public Power Association

Public power utilities aren’t only concerned with protecting the electric grid from cyber attacks, they’re also busy countering a far more pernicious foe: the squirrel!

Squirrels are among the top causes of power outages across the U.S.

In 2016 alone, utilities reported 3,456 outages caused by the ubiquitous rodents that cut off power to more than 193,873 customers. Utilities using the American Public Power Association’s eReliability Tracker system help us to get a better picture of the timing and trends in squirrel-related outages through the year. Four years into tracking, the trends are clear — expect a higher incidence of squirrel-related outages in the spring and fall.


The chart shows the rate of sustained outages (5 minutes or longer) per 1,000 customers from month to month from approximately 200 utilities submitting data. The pattern of squirrel-related outages in 2016 is consistent with previous years, however last year saw a higher rate of outages in October and November. Factors that affect squirrel behavior from year to year may include weather, changing habitat, and population.

Knowing when the furry critters are out in force is only the first step in helping utilities protect transmission and distribution lines and other equipment from potential damage. Public power utilities that can easily spot trends in outage locations and causes can more efficiently allocate deterrent equipment to areas likely to experience squirrel-related disruption.

Utilities can install deterrents like wheels, cages, or guards to keep equipment — and squirrels — safe. They can track which deterrents are effective and worth investing in.

In addition, utilities can use an information service like the eReliability Tracker to collect and analyze outage and restoration data. Monthly reports provide snapshots of reliability performance, identify problem areas and common outage causes, and help to calculate IEEE 1366 reliability indices. An annual national reliability report helps utilities to benchmark reliability performance against similar utilities.
Public power utilities can subscribe to the eReliability Tracker here. For a limited time, small utilities that are new to the service can take advantage of funding from the Department of Energy to get a discounted 3-year subscription.


Alex Hofmann

Alex Hofmann

Energy and Environmental Services Director

One Comment

  1. Curious if the outages are mostly tied to the invasive and prolific gray squirrels. In the UK, there’s an unofficial ‘war’ on these ‘tree rats’ which carry squirrel pox and are harming if not eliminating the native species populations. Prince Charles has even called for sterilization with Nutella bait!

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