Network Data Wiring Basics with Fiber Optic Cables

Computers, telephones, fax machines and other telecommunications equipment are connected by data wiring networks. In order to support increasing traffic, data wiring using fiber-optic cables has become the standard.

Fiber-optic Cables

Fiber-optic cables are made of glass fiber and carry data in energy packets that travel in photons at the speed of light. These cables can carry over 150 times the amount of data that can be conveyed by copper wiring, and over much longer distances. Data streams can travel through fiber-optic cables at different light wavelengths, allowing simultaneous transmission of different data packets through the same cable.

Advantages of Fiber-optic Cable

Because of its flexibility, light weight, small diameter and resistance to interference (called "cross-talk") from other electromagnetic sources, fiber-optic cable has become the preferred standard for all kinds of data transmission including cable TV, telephone, business communications networks and, most importantly, the Internet. To minimize electromagnetic interference in large networks, it is recommended that the fiber-optic cables be placed no closer than 3 inches (7.5 cm) to any copper electrical cable. Laying the cables into thin steel trays also reduces cross-talk and prevents twisting and slipping.

Standard Wiring for Fiber-optic Cable Networks

The standard wiring schematic used in fiber-optic cables has 8 cables, called twisted pairs, and is attached by a plug called RJ45. The 8 wires are labeled in pairs of 4 colors: orange, green, blue and brown. The blue and blue/white striped wires are always in the center of the schematic, with the others placed in varying order around them. Since 2008, the standard schematic has been changed to improve transmission strength: the orange wires replaced the green at the top of the array. As data transmission speeds increase, the wiring standards improve to be able to carry the traffic. Category 6a wiring schematics can handle 500 Megahertz, while Category 7 and 7a, rolling out in 2010, will be able to handle 600 and 1000 Megahertz, 4 times Category 5's capacity. Today's fiber-optic cables will be able to handle 1 Terahertz of transmission frequency.

Length of Fiber-optic Cables

For maximum efficiency, the standard length of a single fiber-optic cable strand, uninterrupted by hubs, routers or other distributors, should be no more than 330 feet (100 meters).

Connecting Cables into Networks

Hubs connect fiber-optic cables into networks. Plug I is at the computer end of the cable and the Plug II connects to the hub. Cross-wiring at the opposing ends of the cable determines which plug goes where, since they look identical from the outside.

How to Decide Your Data Network Needs

The type of environment where you will use the network, what you can afford to install, and your current and estimated future communication requirements will be the key factors in deciding how to lay out your data network. Category 5e fiber-optic cable can carry data in packets up to 100 megabits (100 Mb) in size. If all the components in your data network will send and receive data in gigabit packets (1000 Mb or 1Gb), you should use Category 6 or higher fiber-optic cables.