Lessons from a flood

Communications News, May, 1998 by Rick Muscoplat

Communications managers in Grand Forks, N.D., find out a phone jack isn't just a phone jack.

They're the least expensive part of a communications network, yet the differences between modular jacks can mean the success or failure of a business. Just ask the business owners in Grand Forks, N.D.

Last spring, Grand Forks was inundated by floodwaters. Emergency communications stayed up and running, but some business and residential communications took, well, a dive.

After the waters receded, disaster recovery teams from US West and Bellcore went in. Their findings? Some phones had dial tone and others did not, yet all were hit with the same floodwater. The jacks made the difference.

"In every case where we had installed an anticorrosive gel-filled jack, we had crisp, clean dial tone," recalls Loren Fritz, director of service assurance for US West. The results from non-filled jacks were pretty dismal in comparison. "Either we had no dial tone or static so bad you couldn't hold a conversation," says US West's Jerry Begley.

For the businesses in Grand Forks, having clean dial tone was the key to getting back on their feet. US West had recently upgraded all the businesses in a shopping center with gel-filled jacks. In every case, those businesses had static-free telecommunications and were open for businesses.

The bottom line is, they all look alike, but they don't all perform alike. Poor jack quality has become such a problem that the Telephone Industry Association last year filed two proposed rule changes with the FCC. The first was adopted and established a standard for gold or gold equivalence for spring wires inside a modular jack. The second was not so successful. It would have required jack manufacturers to attest to their compliance to FCC standards.

In declining, the commission stated:

"We note that substandard plugs and jacks have posed a significant problem for consumers. In particular, such plugs and jacks may be difficult to interconnect and may lack the gold plating on the contact interface needed to prevent interference. We conclude, however, that an attestation requirement is not essential for the prevention of network harm."

The FCC has to worry about network harm, but you have to worry about call reliability--especially in today's phone-dependent business environment.

Modular jack corrosion has been an issue since the jack's debut in 1972. It's most noticeable in humid environments. Jacks in Miami, for example, fail at a significantly higher rate than those in Chicago. Humidity sets up an electrochemical process (corrosion) between the spring wires. That corrosion can cause phone line failure in as short as one week.

Gold is inert--it can't corrode. But the base spring-wire material is not gold--it is a combination of several metals, including nickel, brass, and phosphor bronze. The FCC standard for gold plating calls for a minimum of 1.27 microns. Less than that results in accelerated corrosion. More gold slows the process but does not eliminate it.

Bellcore technical staff member Ken Moyers explains what's going on, "If I take two little gold wires, place them .018 to .20 inches apart, put them into a slightly conductive solution, and put 48 volts DC across them, I can move gold from one side to the other. The driving force is the 48-volt battery that is used to power the telephone network." It's important to note that there are always 48 volts DC at the jack. Once the gold starts to move, it causes the rest of the gold plating to rupture. It's like a paint chip on your car that starts to rust and blister.

Where do you get a conductive solution? Most jacks are mounted near the floor, resulting in a temperature difference and condensation. That's one source. Then there's normal humidity, vapors from cleaning chemicals, salt, carpet shampoos, glass cleaners, even off-gassing from plastics. All act as conductive agents.

Moyers and other Bellcore technical staff members took the lead in searching for a way to seal the modular jack connections. They needed some kind of gel that would stay inside the jack, conform to a plug, return to its original shape if the plug was removed, and seal off the gold wires from humidity--with or without a plug engaged.

Raychem Corp., Menlo Park, Calif., developed a product called GelGuard that met all the criteria. CSI/Suttle Apparatus, Hector, Minn., designed the jack, building a special cavity to hold the gel. That left the problem of sealing the jack connections to the premise wiring.

Phone cable can wick up to 1 inch of water of humidity per day. On less humid days, the moisture reverses direction and flows down toward the connection screws. It was obvious the screws had to go. To seal off this connection, the parties opted for 3M's Scotchlock brand of encapsulant-filled connectors. Now, all the connections are sealed.

Muscoplat is a telecommunications freelance writer and has worked in the industry for 16 years.