Squirrels find the Guthrie Guard shocking but non-lethal. What looks like a giant red tarantula and prevents most outages caused by squirrels and other animals? Just ask Jim Guthrie, a retired electric-utility worker, who has spent considerable time working on the Guthrie Guard, a squirrel guard that resembles a tarantula. The device is an electrostatic and physical barrier that attaches quickly to energized electrical insulators and bushings.
The results of field tests involving MidAmerican Energy, Davenport, Iowa, U.S., and Eastern Iowa Light and Power Cooperative, Wilton, Iowa, have surprised even the Guthrie Guard's inventor.
In May of 1993, MidAmerican Energy (then operating as Iowa-Illinois Gas & Electric) had six linemen install 260 Guards in two afternoons along a particularly troublesome distribution circuit in Coralville, Iowa.
"That circuit was selected for field testing because of its history of numerous animal contacts--including 14 outages in just one month," Guthrie said. "This is a region where 69% of all outages are due to animal contacts, and they told me then that they'd be thrilled with a 30% reduction." A year later, there had been no outages on lines on which the Guards had been installed.
MidAmerican Energy continues to use the Guthrie Guard in troublesome areas. The utility estimates that the cost of the Guards could quickly pay for itself when considering the US$100 it would cost to send a truck and a crew out to install a new fuse.
Melvin Nicholas, manager of the Eastern Iowa Light and Power Cooperative, said his co-op, which serves 20,000 customers in a dozen rural counties, experiences a high number of outages each year caused by squirrels and raccoons. Nicholas said that in 1993, the more than 12,000 overhead transformers in his system did not have animal barriers.
However, Roger Sessler, Eastern Iowa Light and Power's operations manager, said results of preliminary field tests of the Guthrie Guards were encouraging enough that the co-op has since installed Guards on approximately 600 transformers, generally in wooded areas.
The Guards are designed to be attached to energized equipment with a conventional hot stick. Sessler said that field testing has shown the Guthrie Guards to be easy and convenient to install.
Sessler estimates a two-man call during off hours to restore power after an animal outage costs US$200 or more. But, he said, that's not his first concern.
"Sure, there's cost involved in animal outages, but I look at it more as an inconvenience and nuisance to customers," Sessler said. "Don't get me wrong, money is also important. But good member relations and good continuity of service are important, and this (Guthrie Guard) appears to be an excellent tool in providing that."
The animal guard is manufactured by the Iowa City-based Guthrie Corp. According to Guthrie, his Guard offers electric utilities plagued by animal outages the proverbial ounce of prevention. And, Guthrie notes, his invention is humane.
"Once installed, the device is designed to acquire an electrostatic charge from its close proximity to the energized primary conductor," he said. "Squirrels caught on video making contact with the guard found it shocking, but non-lethal, much like an electric-fence contact. But it's enough of a jolt to train them not to make future contacts."
Tom Walsh is an award-winning medical, science and business writer for a variety of regional, national and international newspapers and magazines. He is also a public relations consultant with clients in the aerospace, banking and broadcasting industries. He is a graduate of the University of Iowa School of Journalism and Mass Communications.