Service drop cables with a SCRAMessenger keep squirrels at bay

Problem: squirrels have a taste for aluminum

Squirrels can be seen as cute, frisky, little creatures or as a royal pain in the neck. It all depends on your perspective. For energy companies, squirrels tend to fall in the second category. Squirrels, equipped with two pairs of sharp incisors that grow continually, need to gnaw on things to keep their teeth short. That can mean significant damage to overhead service entrance installations in some parts of the country. When a major utility company in the Carolinas saw rising problems from gnawing squirrels, Southwire provided a solution.

“It turns out that aluminum wire has an attractive consistency for gnawing,” said Stephen Spruell, Southwire senior product engineer. “The bare aluminum neutrals on overhead service drop cables are a convenient target. We’ve seen this gnawing problem primarily on service drop cables in areas that are heavily wooded.”

Squirrels don’t seem to bother energized phase conductors, but there have been situations where the aluminum in a bare ACSR neutral was totally gnawed away, leaving nothing but the steel core. In some cases, squirrels chewed through a brand-new cable neutral in a few weeks.

When system grounding is compromised, the results can be unstable voltages at the service and potentially unsafe conditions. The problem shows up primarily in older residential areas where mature trees surround the service drop cables. Speculation is that as urban development reduces squirrel habitat, the animals are concentrating in the remaining trees.

Southwire study points to a unique solution

Responding to the customer need, Southwire conducted a year-long field study followed by testing at an independent research laboratory licensed to do animal research. Results pointed to Southwire’s SCRAMessenger (Southwire Copper Rodent Averse Messenger) copper neutral as the alternative.

“Testing showed squirrels just don’t like the harder surface and non-abrasiveness of our SCRAMessenger copper,” Spruell said. “We have installations that have been in place for more than a year without any sign that the SCRAMessenger has been touched by squirrels.”

The innovative, squirrel-resistant service drop, called SquirrelShield™, is constructed like a standard service drop cable, but uses a bare, hard-drawn SCRAMessenger copper neutral. The conductivity of copper allows a slightly smaller neutral, but there is no difference in installation or allowable span. Southwire’s hard-drawn copper provides tensile strength to support the cable without a steel core.

SquirrelShield comes in a range of common service entrance sizes

SquirrelShield service drops come with phase conductors from #4 AWG to 4/0. Cost-saving reduced-neutral designs are available with phase conductor sizes down to #2 AWG. Insulation can be either polyethylene (PE) or cross-linked polyethylene (XLPE), which is tougher and allows higher emergency operating temperatures.

“There really isn’t a standard service drop cable offering on the market that addresses the issue of squirrel damage,” Spruell said. “Now a solution is available. With SquirrelShield in production, we expect that more people will take action on a serious problem that has left their customers at risk.”