Plenum-rated 18/2 wire uses a CL3P or CMP jacket for air-handling spaces, while riser-rated wire uses a CL3R or CMR jacket for vertical runs between floors. General-purpose 18/2 wire uses a CL2 rating for typical security, alarm, intercom, audio, and control-panel connections where plenum or riser-rated cable is not required.

Choose shielded 18/2 wire when the cable will run near equipment or wiring that may introduce electromagnetic or radio-frequency interference, such as motors, power lines, or other high-noise sources. Choose unshielded 18/2 wire for many standard security, alarm, intercom, control, and audio connections where interference is less likely and a shield is not required by the system design.

18/2 wire supports low-voltage connections in security and alarm systems, including keypads, sounders, strobes, and control panels. It also works for intercoms, audio devices, and access control equipment that use two-conductor wiring.

When selecting 18/2 wire, compare the cable rating required for the installation, such as CL2 for general-purpose use, CL3R for riser spaces, or CL3P for plenum spaces, along with whether shielded or unshielded construction suits the application. Also review the stranded 18 AWG bare copper conductor construction, required certification or jacket markings, and package length, with options in this assortment ranging from 500 feet to 1,000 feet.