Underwriters Laboratories provides additional information on cable type designations and intended use through their UL Product iQ link. Power-limited Circuit Cable is covered under UL product category QPTZ which states the following:

USE

This category covers power-limited circuit cable intended for use in Class 2 or Class 3 circuits as described in Article 725 of ANSI/NFPA 70, "National Electrical Code" (NEC).

PRODUCT MARKINGS

Cable with a nonmetallic jacket is identified by a marking on the surface of the jacket or on a marker tape under the jacket. Cable with an outer metal sheath is identified by a marker tape under the armor. This marking includes one of the following Type designations:

CL2P or CL3P — Indicates cable intended for use in Class 2 or Class 3 circuits within buildings in ducts or plenums or other spaces used for environmental air in accordance with Section 725.154 of the NEC^®. This cable exhibits a maximum peak optical density of 0.5, a maximum average optical density of 0.15, and a maximum flame spread distance of 5 ft when tested per ANSI/NFPA 262, "Standard Method of Test for Flame Travel and Smoke of Wires and Cables for Use in Air-Handling Spaces."

CL2R or CL3R — Indicates cable intended for use in Class 2 or Class 3 circuits within buildings in vertical shafts in accordance with Section 725.154 of the NEC^®. The flame propagation height of this cable is less than 12 ft when tested per ANSI/UL 1666, "Test for Flame Propagation Height of Electrical and Optical-Fiber Cables Installed Vertically in Shafts."

CL2 or CL3 — Indicates cable intended for general use in Class 2 or Class 3 circuits within buildings in accordance with Section 725.154 of the NEC^®. This cable does not spread flame to the top of the tray in the Vertical-Tray Flame Test in UL 1685, "Vertical-Tray Fire-Propagation and Smoke-Release Test for Electrical and Optical-Fiber Cables."

CL2X or CL3X — Indicates cable intended for use in Class 2 or Class 3 circuits within buildings (1) where the cable is enclosed in raceway or noncombustible tubing, or (2) in nonconcealed spaces where the exposed length of cable does not exceed 10 ft, or (3) in one- or two-family or multifamily dwellings when the cable diameter is less than 0.25 in., in accordance with Section 725.154 of the NEC^®. This cable complies with the VW-1 Flame Test requirements in ANSI/UL 1581.

PLTC — Indicates cable for use in Class 3 circuits within buildings that is suitable for use in cable trays, in accordance with Sections 725.154 of the NEC^®. This cable does not spread flame to the top of the tray in the Vertical-Tray Flame Test in UL 1685.

Cable marked "direct burial, "for direct burial" or "dir bur" is suitable for direct burial in the earth.

Type PLTC cable and cable marked "sunlight resistant" or "sun res" may be exposed to the direct rays of the sun.

Cable marked "wet" or "wet location" is suitable for use in wet locations.