20/2 Shielded Riser Security Alarm Cable - CMR/CL3R Rated, 7 Strand Copper, 1000ft Gray

This is the two-conductor shielded riser cable for the signal runs of a security or low-voltage system: two 20 AWG stranded bare copper conductors, black and red, 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) and CMR under Article 800 for communications. The shield is the point: a reader data pair, a keypad bus, an audio line, or a sensor loop that has to share a riser or a wall with lighting and power wiring picks up less noise under foil than it would bare, and 20 AWG is a step heavier than the 22 AWG most sensor wiring uses, which buys a longer run for anything that also draws a little current. 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. 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

• Riser rated two ways. CL3R under NEC Article 725 and CMR under Article 800, so it's listed for riser shafts, vertical runs between floors, and general in-wall and in-ceiling use on security, control, and communications circuits, and the CL3R listing covers Class 2 circuits under the code's substitution rules.
• Two 20 AWG stranded bare copper conductors. Heavier than 22 AWG for longer signal and light-power runs, 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 sensor pairs.
• Black and red. The standard pair coding for polarity on a DC signal or alarm circuit.
• PVC insulation and jacket. Flexible and easy to strip, 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 or Class 3 circuit calls for.
• 3.61 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 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, intercom and entry-phone audio lines, line-level audio between a paging amplifier and a source, door and window contacts and sensor loops routed past fluorescent lighting or motor circuits, thermostat and damper control pairs in a noisy mechanical room, and any two-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. 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: a 20 AWG pair is about 20 ohms per 1000 ft round trip, so a 12 V reader drawing 200 mA at 300 ft loses about 1.2 V; for a strike, a siren, or anything heavier, use an 18 AWG pair instead. 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. CL3R and CMR cover risers and general use but not return-air plenums; a run through a plenum ceiling needs a CL3P cable. If the route is quiet, the unshielded riser cables do the same job for less and terminate faster. 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

Shielded