Insulators Home > My Collection > Miscellaneous > 3M Guthrie Guard
Material: Plastic with Metal Wires
Manufacturer: 3M
Mnrf Code: GG-1525
Year: 1998-2003
Size: 8.5 inch height; 10 inch width
Usage: shocks animals that get too close to electrical insulators, before they can cause outages by frying themselves on the equipment
Marking: 3M / GG1525
Acquired: May 10, 2004 - eBay, $7.43
Notes: Jim Guthrie, a retired electric-utility worker from Iowa-Illinois Gas & Electric, invented the first version of the Guthrie Guard in 1992, and received US patent# 5,648,641 for it in July 1997. 3M purchased the patent rights in April 1998, and now calls it an "Electrostatic Animal Guard". 3M's GG-1525 product page says it can be used on insulators with neck diameters from 1.5 to 2.5 inches, up to a 35 kV voltage.
News articles explain how several utilities use Guthrie Guards to reduce squirrel-induced outages: Entergy, FEM Electric Co-op in South Dakota, and several Iowa power companies. Jim Guthrie describes how it works: "Once installed, the device is designed to acquire an electrostatic charge from its close proximity to the energized primary conductor. 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."
There is also a competing product, the Rauckman ZAPShield (first used in 2003; price as of July 2004 is $11.90 each) and a larger version of it called the Wildlife Shield (first used in 1997 or 1998; price as of July 2004 for distribution-class is $12.45 each, and for substation-class is $22.60, $44, or $49 each depending on size). It received US patent# 5,864,096 in January 1999.
Insulators Home > My Collection > Miscellaneous > 3M Guthrie Guard
Contact: A.C. Walker