18/2 CL3P CMP Plenum Rated Shielded Cable – 500ft Stranded Bare Copper White

18/2 CL3P CMP Plenum Shielded Cable – Flexible EMI-Protected Bare Copper for Security and Low-Voltage Installs

18/2 CL3P CMP plenum shielded cable is the compact, flexible choice for security alarm, intercom, and low-voltage circuit installations in plenum air-handling spaces where EMI protection is required. This 500ft white pull box delivers 18AWG stranded bare copper conductors, an aluminum foil shield with drain wire, and a CL3P/CMP dual-rated jacket — all optimized for routing through tight ceiling cavities, risers, and conduits in commercial and residential buildings.

Furthermore, this cable meets the fire safety performance requirements established under NEC Article 800 for CMP-rated Communications Multipurpose Plenum cable (nofollow). As a result, it is fully approved for installation in HVAC return-air ducts, suspended ceiling plenums, and every air-handling space where low-smoke, flame-retardant cable is required by code. Consequently, contractors, integrators, and AHJs can approve this product with confidence on any inspected commercial or residential job site.

Key Features of Our 18/2 CL3P CMP Plenum Shielded Cable

• Aluminum Foil Shield with Drain Wire — Complete EMI Suppression: This 18/2 CL3P CMP plenum shielded cable carries an overall aluminum foil shield that wraps both conductors, with a bare copper drain wire for single-point grounding at the panel or controller. The shield blocks electromagnetic interference (EMI) and radio frequency interference (RFI) from fluorescent ballasts, HVAC motors, power wiring, and adjacent cable bundles in commercial ceilings. Moreover, shielding is critical on intercom, paging, and low-voltage audio circuits where even small amounts of induced interference can introduce audible hum, noise, or intermittent signal loss.

• 18AWG Stranded Bare Copper Conductors: Two 18AWG stranded bare copper conductors deliver excellent conductivity and outstanding flexibility for routing through tight ceiling spaces, conduit bends, and junction box entries. The stranded construction is particularly advantageous over solid wire in applications requiring repeated movement or where cable must navigate multiple bends without kinking. Additionally, bare copper ensures long-term conductivity and resists the corrosion issues that affect copper-clad aluminum (CCA) in humid ceiling environments.

• CL3P and CMP Dual-Rated Plenum Jacket: The white outer jacket carries both CL3P (Class 3 Plenum) and CMP (Communications Multipurpose Plenum) certifications, verified under UL 13 for plenum cable construction and materials (nofollow). This dual rating satisfies NEC Articles 725 and 800 simultaneously, giving inspectors and AHJs complete flexibility in classifying the installation. In other words, one spool of this 18/2 CL3P CMP plenum shielded cable legally covers every plenum, riser, and air-handling installation scenario.

• Stranded Construction for Easy Routing and Termination: Unlike solid conductor cable, the stranded conductors in this cable bend freely without fatiguing or fracturing during installation. As a result, installers can route this cable through crowded ceiling cavities, down through wall cavities, and into device backboxes without breaking a conductor or losing pull force partway through a run. Furthermore, stranded wire terminates more cleanly under screw terminals and wire nut connections than solid wire, making device wiring faster and more reliable.

• Wide Low-Voltage Application Compatibility: This cable is suitable for security alarm wiring, intercom circuits, paging systems, access control signal circuits, and general low-voltage control applications in plenum spaces. Consequently, it functions as a versatile shielded rough-in cable for AV integrators and low-voltage contractors who need EMI protection across multiple system types within the same commercial building.

• 500ft Pull Box Packaging: The 500ft pull box delivers enough cable for multiple circuit runs on a commercial floor without mid-run splices. Additionally, the pull box format provides tangle-free payout during active ceiling pulls, reducing installation time and cable waste on busy multi-circuit jobs.

• Durable Low-Smoke White PVC Jacket: The white jacket is formulated to resist flame spread and minimize toxic smoke output in fire conditions. Therefore, it fully satisfies the ANSI/NFPA 90A requirements for cable materials in air-handling plenum spaces (nofollow) that govern commercial building construction throughout the United States.

• Compact 18AWG Profile for High-Density Ceiling Pathways: The smaller 18AWG diameter makes this cable ideal for conduit fill calculations on projects where 16AWG cable would exceed the allowable fill percentage. As a result, more circuits can share a single conduit, reducing material and labor costs on high-circuit-count commercial security rough-ins.

Why Choose This 18/2 CL3P CMP Plenum Shielded Cable for Your Installation?

The combination of stranded conductors and aluminum foil shielding makes this 18/2 CL3P CMP plenum shielded cable uniquely suited to the most demanding intercom, paging, and low-voltage audio circuits in commercial plenum environments. Stranded wire flexes without breaking during the sharp bends common in ceiling and wall installations, while the overall shield keeps the signal clean regardless of what other cables share the pathway. In contrast, unshielded 18AWG cable in electrically active commercial ceilings is susceptible to 60Hz hum on audio circuits and false triggers on low-voltage sensor circuits — problems that are expensive to diagnose and impossible to fix without recabling. Moreover, the white jacket meets the industry color-coding convention for intercom, paging, and audio wiring, keeping circuit identification consistent with the rest of the low-voltage installation. For applications where shielding is not required and budget is the priority, our unshielded alternative is the 16/2 CL3P CMP Plenum Unshielded Cable – White 500ft (DoFollow).

The CL3P/CMP dual rating on this 18/2 CL3P CMP plenum shielded cable is particularly important for projects that mix audio and communications circuits in the same ceiling space. CL3P satisfies NEC Article 725 for power-limited Class 3 circuits — the classification that covers intercom, paging, and audio distribution wiring. CMP simultaneously satisfies NEC Article 800 for communications wiring. Therefore, specifying this single cable eliminates the documentation complexity of maintaining separate cable types for each NEC article, and ensures that any AHJ inspection passes without a substitution dispute. Additionally, the CMP rating permits this cable to be installed anywhere a lower-rated CMR or CM cable is required, giving contractors maximum flexibility when routing across multiple building zones. For a heavier-gauge shielded option where current capacity or run length requires 16AWG, consider our 16/2 CL3P CMP Plenum Shielded Cable – White 500ft (DoFollow).

At 18AWG, this 18/2 CL3P CMP plenum shielded cable is the most compact and lightest shielded plenum cable in the 52Networks low-voltage family, making it the preferred choice for intercom handset wiring, paging speaker feed circuits, and low-current sensor circuits where the smaller gauge is both electrically sufficient and practically advantageous for conduit fill. Furthermore, the 500ft pull box is perfectly sized for single-floor security and intercom rough-in jobs, providing enough footage to cover all device runs without waste. For the complete range of CMP-rated plenum security and audio cables across all gauges, browse our full Speaker and Security Cable collection (DoFollow).

Frequently Asked Questions

Q: What is the difference between stranded and solid conductors, and why does it matter for plenum installations?

Stranded conductors like those in this 18/2 CL3P CMP plenum shielded cable consist of multiple thin copper wires twisted together, while solid conductors are a single wire per gauge. Stranded wire is significantly more flexible than solid wire of the same gauge — it bends without fatiguing, routes around corners without kinking, and is far less likely to fracture at a termination point under vibration or thermal cycling. As a result, stranded cable is the preferred choice for plenum installations that require routing through multiple bends, drops through wall cavities, or connection to devices that experience movement or vibration such as intercom handsets and paging speakers. Additionally, stranded conductors terminate more cleanly under push-in and screw-type terminals at intercom units, paging amplifiers, and security panels, reducing the risk of a broken conductor creating an intermittent open circuit. In contrast, solid conductors are preferred for longer home-run pulls where pull tension is a concern.

Q: Is this 18/2 shielded plenum cable appropriate for intercom systems and paging circuits?

Yes — this 18/2 CL3P CMP plenum shielded cable is ideally suited for intercom systems and paging circuits in commercial plenum environments. The 18AWG stranded bare copper conductors provide excellent flexibility for routing to intercom stations and paging speakers, while the aluminum foil shield prevents the 60Hz audio hum that unshielded cable picks up from adjacent power wiring and lighting circuits in commercial ceilings. Furthermore, the CL3P/CMP dual-rated jacket satisfies both NEC Article 725 (intercom and paging as power-limited Class 3 circuits) and NEC Article 800 (communications wiring classifications) in the same plenum space, ensuring full code compliance regardless of how the AHJ chooses to classify the circuit. As a result, this cable is used by commercial AV integrators as the standard shielded intercom and paging rough-in cable on projects where plenum compliance and audio signal quality are both required.

Q: How should the aluminum foil shield on this cable be grounded at the device or panel end?

The aluminum foil shield on this 18/2 CL3P CMP plenum shielded cable should be grounded at one end of each cable run only — typically at the head-end equipment location such as the intercom master station, paging amplifier, or security panel. At the device end of the run, the drain wire should be cut back and left floating to prevent the formation of a ground loop, which would introduce 60Hz hum directly into the audio signal path. At the equipment end, connect the drain wire to the chassis ground or designated shield terminal as specified by the equipment manufacturer. Moreover, keep the unshielded section of the drain wire as short as possible at the termination point, since an exposed drain wire can act as an antenna and re-introduce the interference the shield was designed to suppress. Always follow the intercom or paging system manufacturer’s specific grounding instructions, as different system architectures handle shield termination differently.

18/2 CL3P CMP plenum shielded cable from 52Networks delivers EMI protection, CMP-certified fire safety, and stranded bare copper flexibility for every commercial security, intercom, and low-voltage installation. Order today and receive a 500ft pull box ready for your next plenum project.