Daniel L. Pohnert, PE
Fred Wilson & Associates Inc.
Jacksonville, FL
As a follow-up to the April 1997 "Ask Donna" column that discusses rodent damage (see "Rodent damage to cables," page 44), the best source of information on rodent damage to cabling is a paper presented at the Instrument Society of America (now called the International Society for Measurement and Control) convention in 1988 by Roger H. Keith, PE, 3M (isa 1988 paper #88-1653).
The extent of rodent damage to cable depends on how much the rodent`s jaw opens in relation to the diameter of the cable and the tensile strength and hardness of the cable. When rodents chew cable, they gnaw on it without allowing any of the material into their mouths, so poison and bad-tasting materials will not affect a rodent`s choice of cables. Also the resistance between the teeth and from the paws is 20 kilohms to 10 megohms, so the animal is unaffected by voltage.
The paper I`m referring to outlines several standard tests for rodent damage to cable and should be required reading by anyone interested in protecting cable against rodent damage.