Rats! The Cable Is Down Again

Rodents love to chew on them, a problem that costs the industry hundreds of millions each year. One solution: Chile-pepper casings

In a cage in animal psychologist Stephen Shumake's lab at the National Wildlife Research Center in Fort Collins, Colo., a gopher seizes a fiber-optic cable in its front paws and begins to gnaw on it. In short order, the rodent has used its razor-sharp front incisors to chew through the steel coating tape protecting the glass strands that make up the cable.

One of his rodent companions isn't so lucky. Gopher No. 2 has received the "hot pepper cable," which Shumake has smeared with a jelly-like coating spiked with capsaicin -- the chemical that puts the pow in chile peppers. Not realizing that he is chewing on the high-tech equivalent of an eye-watering habanero pepper, the gopher chews for a while before it stops and begins to gnash its teeth. It pauses, as if pondering the scenario, then drops the cable to move on to easier eats.

"It's kind of interesting watching the gophers gnaw on cable samples. They do some gnawing, lift their head up, and mash their incisors back and forth. They are not easily discouraged," says Shumake.

CABLE CONNOISSEURS. Shumake's chile concoction is just one tiny weapon in the wide-ranging battle to keep gophers, woodchucks, beavers, and rats from chomping their way through America's data lifelines. Dow Chemical, which manufactures a specialized steel coating to protect cables from rodents, counts 2,000 animals around the world that are FOC -- fond of cable. Here's a tidbit that may surprise you: The cable industry cites the work of rodents as the No. 1 cause of service interruptions, tied with technical problems.

It's not the taste that attracts the critters. Rodents chew on cable to grind down their incisors, which grow for their entire lives and can become too long. "They love to chew. If they don't chew, their teeth get so big they starve to death," explains Frank Steffen, a managing director at telecom services provider Lexent.

Mankind can claim some victories: For example, big fiber-optic providers Qwest and AT&T, which use heavy corrugated steel to protect their backbone networks, say less than 1% of their outages are caused by animals. Their networks account for only a small portion of the millions of miles of wires strung across America, however.

Many smaller telcos, local carriers, universities, rural cable-TV providers, and others face constant attacks on their aging and sometimes underprotected networks. This problem can be particularly troublesome in outlying areas. "Anything beyond the city architecture, you are often talking about single points of failure," says Jonathan Chauvin-Blitt, president of Network Systems & Services for ITT Industries.

COSTLY CHOMPING. Whenever a cable gets cut or damaged, repair costs start in the thousands of dollars in material and man-hours, not to mention the down time for customers. That adds up to hundreds of millions in worldwide repair costs each year, the cable and wire industry claims.

Even if a rodent barely pierces the sheathing, the cable could be shot. "If they just chew a little on the cable and penetrate the inside jacket, and if moisture or water gets in and freezes, that's the end of your cable," explains Steffen. The ice could expand and break the glass fibers. Even in warmer climes, the water bonds to the silica fiber strands and yellows the glass, reducing transmission efficiency.

Unfortunately, the methods used by telecoms and cable companies to lay fiber networks plays right into rodent paws and maws. The loose dirt left by trenching creates freeways that entice gophers and woodchucks into the path of least resistance. In major metropolitan areas, cable-layers use sewers and dormant steam tunnels instead of digging new tunnels. Such places also appeal to rats.

Steffen recalls entering the sewer system below the New York Transit Authority's subway station at 34th Street and 7th Avenue. The street above was full of fast-food joints, and the sewer pipe rested directly below the sluicing area for an NTA garbage compactor. "People come down from the street, and before they get on the train they throw stuff in the garbage. The NTA dumps it into the compactor that squeezes out all the juice, and it runs down the tracks into a manhole," says Steffen, who claims that when he first lifted the steel cover, "...all I saw were pink eyes."

The NTA gassed the tunnel to allow for the cable-installation procedure, but the rats have likely returned. With that type of rodent concentration, Steffen says he can't imagine any cable lasting too long.

RODENT IRRITANTS. With so many rodents chewing so much cable, scientists such as Shumake have been researching alternative ways to stop the gnawing. One method involves running a light electrical current down the metal jacket to give the rodents "...the same taste you get when you chew on a piece of tinfoil," says Steffen.

At least two companies, Nippon Industries in Japan and Burlington Bio-Medical & Scientific in Farmingdale, N.Y., have created chemicals that can be used to treat cables with concentrated hot-pepper extracts. Burlington also offers extremely bitter substances that can be painted on surfaces or bonded to the plastic sheathing material of cables. The consumer version of the product, used to dissuade animals from eating flowers or wood "...has a truly vile, bitter, lingering taste," according to the company's Web site.

Shumake has created a jelly-like substance laced with high concentrations of capsaicin to smear between the outer and inner layers of fiber-optic cables. Because most rodents' incisors sit outside their mouths, the burning sensation that might send a human running for water merely causes an irritation to rodents, says Shumake. They also rub the capsaicin onto their coats when grooming, causing some unpleasantness, he adds.

One small inconvenience for rodents, one big step for the flow of data through the wired world's increasingly vital fiber networks.