The environment determines whether cable should be shielded or unshielded.

Shielding is the sheath surrounding and protecting the cable wires from electromagnetic leakage and interference. Sources of this electromagnetic activity (EMI)—commonly referred to as noise—include elevator motors, fluorescent lights, generators, air conditioners, and photocopiers. To protect data in areas with high EMI, choose a shielded cable. Shielding also protects cables from rodent damage. Foil is the most basic cable shield, but a copper-braid shield provides more protection. Use a foil-shielded cable in busy office or retail environments. For industrial environments, you might want to choose a copper-braid shield.

For quiet office environments, choose unshielded cable.

Stranded vs. Solid Cable

Stranded cable is for use in shorter runs between network interface cards (NICs) and wallplates or between concentrators and patch panels, hubs, and other rack mounted equipment. Stranded-conductor cable is much more flexible than solid-core cable. However, attenuation is higher in stranded-conductor cable, so the total length of stranded cable in your system should be kept to a minimum to reduce signal degradation.

Solid cable is designed for both backbone and horizontal cable runs. It’s for use in runs between two wiring closets or from the wiring closet to a wallplate. Solid-conductor cable shouldn’t be bent, flexed, or twisted repeatedly. Its attenuation is lower than that of stranded-conductor cable.