18 AWG 2-Conductor Shielded Plenum Alarm Cable - CMP Rated, 1000ft

In an office, school, hospital, or store, the space above the drop ceiling is usually a return-air plenum, and any low-voltage cable that runs through it without conduit has to be plenum rated. This is the two-conductor shielded plenum cable for the longer or noisier signal runs of a security or low-voltage system in those buildings: two 18 AWG stranded bare copper conductors, black and red, under an overall aluminum foil shield and a white low-smoke PVC jacket that carries the plenum listings. It's rated CL3P under NEC Article 725 for Class 3 power-limited circuits (and by the code's substitution rules for Class 2 as well), CMP under Article 800 for communications, and FPLP under Article 760 for power-limited fire alarm circuits. The shield is the point: a reader data pair, a keypad bus, an audio line, or a sensor loop that has to share a ceiling space with lighting ballasts, VFDs, and HVAC motors picks up less noise under foil than it would bare. And 18 AWG, with about half the loop resistance of 22 AWG, is the gauge for a pair that has to go a long way or carry a little current on the way, so the same cable that shields a reader's data can also feed the reader. The 7-strand conductors bend around a ceiling and land in a terminal block more easily than solid wire.

CL3P and CMP cover return-air plenums, drop ceilings, and raised floors, and every riser and general-purpose run below that. The cable is ETL Listed, RoHS compliant, and made in the USA, and it comes in a 1000 ft pull box with sequential footage marks on the jacket.

Features

• Plenum rated three ways. CL3P under NEC Article 725, CMP under Article 800, and FPLP under Article 760, so it's listed for return-air plenums, drop ceilings, and raised floors on security, control, communications, and fire alarm circuits alike, and for every riser and general-purpose run below that; the CL3P listing covers Class 2 circuits under the code's substitution rules.
• Two 18 AWG stranded bare copper conductors. About half the loop resistance of 22 AWG, for long signal runs and pairs that also carry power, on 7-strand conductors that bend around a ceiling and seat in a terminal block without fighting.
• Overall aluminum foil shield. 100% coverage against induced noise from ballasts, VFDs, and HVAC equipment sharing the ceiling space, for data, audio, and sensor pairs.
• Black and red. The standard pair coding for polarity on a DC signal or alarm circuit.
• Low-smoke PVC insulation and jacket. The low-smoke compounds a plenum listing requires, with a 0.015 in jacket wall over the shield.
• White jacket. Reads as general-purpose low-voltage in a ceiling 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.
• 4.11 mm outer diameter. Slim enough to bundle by the dozen and fish through a tight ceiling.
• ETL Listed, RoHS compliant, made in the USA.
• 1000 ft pull box. Sequential footage marks on the jacket; pays out from the box without a spool stand, and the box stacks in a van.

Where It Fits

It suits card reader and keypad data pairs on access control doors, RS-485 and panel bus runs where the manufacturer accepts a shielded untwisted pair and the run is long, line-level audio between a paging amplifier and a source, intercom and entry-phone audio lines, door and window contacts and sensor loops routed through a ceiling full of ballasts and HVAC equipment, thermostat and damper control pairs above a plenum ceiling, power-limited fire alarm circuits that call for a shielded stranded pair, and any two-conductor low-voltage run through a plenum ceiling in an office, school, hospital, hotel, or store where the route is electrically noisy or long.

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. Check the reader or panel manufacturer's wiring guide before you pull, since RS-485 and some keypad buses specify a twisted pair, and a foil shield adds capacitance that can shorten the rated run on a high-speed bus. Run the voltage-drop calculation on any pair that also carries power: an 18 AWG pair is about 13 ohms per 1000 ft round trip, so a 12 V reader drawing 200 mA at 300 ft loses about 0.8 V, and a 12 V strike drawing 0.5 A at 200 ft loses about 1.3 V; a strike or a siren doesn't need the shield, so the unshielded 18/2 plenum does that job for less and this cable can stay on the signal. Keep the circuits in their classes: Class 2 and Class 3 circuits can use this cable, but a Class 1 circuit can't, 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. Plenum-rated cable is for the air-handling space, not for inside the ductwork itself. If the ceiling isn't a plenum, a shielded riser cable does the same job for less. Plenum compounds are stiffer than ordinary PVC, so give it a generous bend radius even though the cable is small. The jacket isn't UV stabilized or rated for wet locations or burial, so an outdoor reader or contact should be fed through conduit or from a cable rated for it.

Specifications

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