18/3 AWG Riser Security Alarm Cable - CMR/CL3R Rated, Shielded, 1000ft Gray

This is the three-conductor shielded riser cable for the circuits that need a pair and a common: three 18 AWG stranded bare copper conductors, black, red, and white, under an overall aluminum foil shield and a gray PVC jacket listed CL3R under NEC Article 725 for Class 3 power-limited circuits (and by the code's substitution rules for Class 2 as well), CMR under Article 800 for communications, and FPLR under Article 760 for power-limited fire alarm circuits. An RS-485 bus with its signal reference, a balanced audio line, a 0 to 10 V control with its common, two sensor loops sharing a return, an intercom station's talk, listen, and common, a strobe with a sync line: each is a three-conductor run, and the shield keeps it quiet past the lighting and power wiring it shares a riser or a wall with. 18 AWG is heavy enough to carry a little power on the way, and the 7-strand conductors bend around a wall cavity and land in a terminal block more easily than solid wire.

CL3R and CMR cover the vertical runs between floors of a multi-story building and every ordinary in-wall and in-ceiling run that isn't a return-air plenum, and FPLR covers the same spaces on a fire alarm system. The cable is ETL Listed, RoHS compliant, and made in the USA, and it comes on a 1000 ft wooden spool with sequential footage marks on the jacket.

Features

• Riser rated three ways. CL3R under NEC Article 725, CMR under Article 800, and FPLR under Article 760, so it's listed for riser shafts, vertical runs between floors, and general in-wall and in-ceiling use on security, control, communications, and fire alarm circuits alike, and the CL3R listing covers Class 2 circuits under the code's substitution rules.
• Three 18 AWG stranded bare copper conductors. A pair and a common, or a data pair and its reference, with about half the loop resistance of 22 AWG, on 7-strand conductors that bend around a wall cavity and seat in a terminal block without fighting.
• Overall aluminum foil shield. 100% coverage against induced noise from lighting, motor, and power circuits sharing the riser or the wall, for data, audio, and control conductors.
• Black, red, and white. Three distinct colors, so the pair and the common are identifiable at both ends without a meter.
• PVC insulation and jacket. Flexible, with a 0.015 in jacket wall over the shield.
• Gray jacket. Reads as general-purpose low-voltage in a wall or a tray, and stays distinct from red fire alarm and blue data cable.
• 300 V, 75 °C. The ratings a Class 2, Class 3, or power-limited fire alarm circuit calls for.
• 4.45 mm outer diameter. Slim enough to bundle by the dozen and fish through a wall or a tight ceiling.
• ETL Listed, RoHS compliant, made in the USA.
• 1000 ft wooden spool. Sequential footage marks on the jacket; put it on a spool stand and it pays out cleanly.

Where It Fits

It suits RS-485 and panel bus runs where the manufacturer accepts a shielded untwisted pair and wants a signal reference carried along, balanced line-level audio between a paging amplifier, a mixer, and a source, intercom and entry-phone stations with talk, listen, and common, 0 to 10 V dimming and damper controls with their common, two sensor or contact loops sharing a return conductor on a noisy route, horn-strobe circuits that carry a sync line, power-limited fire alarm circuits that call for a shielded three-conductor cable, and any three-conductor low-voltage run through the walls and risers of a home, apartment building, office, or store where the ceiling space isn't a return-air plenum and the route is electrically noisy.

Good to Know

Ground the shield's drain at the panel or controller end only and tape it back at the device end; a shield grounded at both ends becomes a loop that picks up the noise it was meant to reject. On an RS-485 run, carry the signal reference on the third conductor rather than on the shield, and check the manufacturer's wiring guide, since some buses specify a twisted pair and a foil shield adds capacitance that can shorten the rated run at high speed. On a balanced audio line, the shield is the screen and not a signal conductor; land it at the source end only unless the equipment manual says otherwise. Run the voltage-drop calculation on any conductor that carries power: an 18 AWG pair is about 13 ohms per 1000 ft round trip, so a 12 V device drawing 200 mA at 300 ft loses about 0.8 V. Keep the circuits in their classes: Class 2 and Class 3 circuits can share this cable, but a Class 1 circuit can't, a fire alarm circuit can't share a cable with a security circuit, and the NEC requires power-limited wiring to stay separated from power conductors in raceways and boxes. Stranded conductors want a ferrule or a proper fold-back before they go under a screw terminal; a stray strand is the short that takes a zone into trouble. CL3R, CMR, and FPLR cover risers and general use but not return-air plenums; a run through a plenum ceiling needs a CL3P or FPLP cable. If the route is quiet, an unshielded cable does the same job for less and terminates faster. The jacket isn't UV stabilized or rated for wet locations or burial, so an outdoor device should be fed through conduit or from a cable rated for it.

Specifications

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