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How-To Guide

Category 5: What It Is and Why We're Using It

The kind of cable that NetDay volunteers install is called Category 5. It's made up of eight color-coded, twisted copper phone wires encased in a sheath, and it costs about 10 cents a foot at computer supply stores. State-of-the-art, it's the same cable on which high-speed networks in most businesses run. If Category 5 cable is installed according to specifications, computer data can travel over it at high speeds. It's also said to have high bandwidth. (Bandwidth refers to the rate at which information that can travel through telecommunications cable or wiring; sending data over a network with higher or lower bandwidth is like letting water flow through a bigger or smaller pipe.)

Fiber-optic cable, which transmits electronic data as light waves, has even greater bandwidth than Category 5 cable, but it's more expensive and requires more expertise to install. However, Category 5 cable cannot be used for runs longer than 328 feet (100 meters), whereas fiber-optic cable can.

What difference does bandwidth make? First, within a school's local network, lots of data will be able to travel very quickly. Students in different schoolrooms will be able to send one another e-mail and text files without hitting a bottleneck that makes them wait for things to come up on screen. They'll also be able to call up one another's pictures and movies. Second, schools won't be a bottleneck in the future, as bigger and bigger chunks of data become available over the Internet. Many phone companies are now replacing old phone networks with high-bandwidth cable.

Category 5 cable will accommodate advances in computer technology for a long while to come. Right now, only 10 percent of all computers in schools are fast enough to make full use of Category 5's data transmission capacity.

"Grange was built in 1973, and the builders left us an empty 1-inch conduit that we used to pull Category 5 cable to the classrooms."

A NetDay technical volunteer from Grange Middle School,
Fairfield, California, on Grange's March 9, 1996, wiring effort