Wire size is normally expressed as AWG (American Wire Gauge). As the AWG number gets smaller the wire diameter increases. For example, a 22 AWG wire is larger than a 28 AWG wire. Wires in a cable are also commonly referred to as conductors. Wire current carrying capacity is affected mainly by wire AWG, temperature, insulation material, and the number of bundled wires in a cable. The chart below is a helpful guide to use when determining the amount of current a cable can carry.

Shielding in a cable is typically a metallic layer placed under the cable jacket and over the conductors. The shield prevents electrostatic or electromagnetic interference (EMI) between the cable conductors and external devices that can corrupt the data being transmitted by the cable. External devices that can cause EMI problems include electrical fans, motors, and switches.

•	Foil/mylar shield - Common for most serial and printer cables. Good resistance to EMI.
•	Foil/mylar plus braid (Double Shield) - Commonly found in USB, Firewire (IEEE-1394) and high end serial and parallel cables. A braid shield is finely stranded wires interwoven in a cylindrical form. Excellent resistance to EMI.
•	Spiral shield - Typically found in highly flexible cables. Similar to a braid shield except the finely stranded wires are applied spirally rather than interwoven. Excellent resistance to EMI.