Summary
Highlights
Network cables are fundamental to connecting devices. Even wireless networks rely on cables to connect access points to the rest of the infrastructure. Proper cabling is crucial for applications to function as expected, requiring careful planning and installation of the correct cable type for the network.
Most wired Ethernet networks use twisted pair copper cables. Wires inside are twisted in pairs, with each pair carrying equal and opposite signals (e.g., Transmit+ and Transmit-). This twisting helps reduce interference and noise, as the receiving device can differentiate the real signal from noise based on the differences in the twisted signals.
Different twisted pair cables adhere to specific standards that define their minimum capabilities. The 'speed' of a cable depends on the signaling coding used, not the cable itself. IEEE 802.3 standards specify the minimum category of cable for different Ethernet standards, such as Category 5 for 1000BASE-T (Gigabit Ethernet) and Category 6 or 6A for 10GBASE-T (10 Gigabit Ethernet) networks. Category 5e (Enhanced) is a common replacement for the deprecated Category 5.
Coaxial cable is another common copper cable type, characterized by an inner conductor for the signal and an outer shield for protection against interference. It's frequently used for cable modems and digital cable for high-speed internet connections.
Twisted pair cables can be unshielded (UTP) or shielded (STP). UTP has no shielding, while STP incorporates shielding around all four pairs or individual pairs to protect against interference. Cable labels use abbreviations like U (unshielded), S (braided shield), and F (foil shield) to indicate the type of shielding for overall cable and individual pairs, e.g., S/FTP (braided shield around cable, foil around pairs).
For connecting buildings, special direct burial STP cables are designed to be installed underground. These cables are waterproofed, often with a gel inside, and are usually shielded to protect against interference and allow for proper grounding. They are structurally similar to indoor shielded Ethernet cables but with added durability and weather resistance.
In commercial buildings, the space above drop ceilings (plenum space) can allow fire, smoke, and toxic fumes to spread rapidly. Therefore, network cables installed in these areas must be plenum-rated. Unlike standard PVC (PolyVinyl Chloride) jacketed cables, plenum cables use fire-rated materials like Fluorinated Ethylene Polymer (FEP) or low-smoke PVC to reduce flame spread and toxin emission during a fire, even if they are less flexible.