Plenum vs. Non-Plenum: What You Need to Know for Security and Access Control Cables

Selecting the appropriate cable type for security and access control systems is one of the most crucial decisions in any commercial project. System reliability, safety, and code compliance all depend on understanding where each cable type is approved for use. One of the biggest distinctions professionals face is between plenum vs. non-plenum cable ratings.

It’s common to discuss this topic because these two classifications directly impact how cabling performs during a fire and how it’s permitted under building codes. Knowing the difference helps one select materials that not only deliver performance but also protect lives and property.

In this post, we’ll explore what separates plenum and non-plenum cables, why the difference matters for security and access control cables, and how to make the right choice for code-compliant projects.

Understanding Cable Ratings in Security and Access Control

In low-voltage systems, cable ratings determine where and how products can be installed within a building. The National Electrical Code (NEC) assigns specific designations that reflect flame resistance, smoke production, and safe use cases.

For security and access control, these ratings influence how cables connect card readers, locks, request-to-exit devices, alarm panels, and cameras. In other words, the correct cable choice ensures systems remain functional and compliant while minimizing fire risks.

The debate around plenum vs. non-plenum isn’t about signal performance. It’s about safety and code requirements in different parts of a building. Both types may carry identical signals and power, but their construction materials and test ratings make them suitable for specific spaces.

What Is a Plenum Cable?

Plenum-rated cables, identified by the CMP (Communications Plenum) designation, are designed for spaces that circulate air as part of heating and cooling systems. These include open return-air spaces above ceilings or below raised floors. Because air movement can carry smoke and toxic gases quickly during a fire, these areas demand cables that resist ignition and limit emissions.

Plenum-rated security and access control cables utilize fire-resistant jackets composed of special fluoropolymers or low-smoke compounds. These materials self-extinguish and produce minimal smoke compared to standard PVC jackets. They must pass stringent flame and smoke tests defined by NFPA 262, the standard for plenum cables.

Common examples include 18/2 shielded plenum control cables for card readers and 16 AWG wire for power delivery in return-air spaces. These options provide safety compliance and maintain signal integrity under high-temperature conditions.

In short, plenum cables are required anywhere wiring runs through environmental air-handling spaces. They help prevent a minor incident from escalating into a major emergency.

What Is a Non-Plenum Cable?

Non-plenum access control wires, commonly labeled as CMR (riser-rated) or CM (general-purpose), are designed for areas that do not handle air circulation, such as wall cavities, conduit runs, or vertical shafts between floors. These cables use standard PVC insulation and jacketing, which offer adequate flame resistance for contained pathways but do not meet the low-smoke requirements of plenum-rated products.

A non-plenum access control cable performs well in typical riser or enclosed environments where the potential for fire spread is limited. Because the materials are less costly, non-plenum cables are often more economical for routes that do not require plenum compliance.

Building codes restrict their use to areas outside of plenum spaces. When chosen properly, non-plenum cables meet NEC safety standards while keeping overall project costs manageable.

Key Differences Between Plenum and Non-Plenum Cables

The primary difference between these two categories lies in material composition, safety testing, and the allowable environments.

• Fire Resistance: Plenum cable resists flames longer and produces less smoke. Non-plenum cable burns faster and releases more fumes.
• Material Construction: Plenum uses fluoropolymer or low-smoke compound jackets, while non-plenum typically uses PVC.
• Use Case: Plenum is required in return-air spaces such as ceilings or HVAC plenums. Non-plenum fits enclosed risers or conduits.
• Cost: Plenum-rated products are more expensive due to stricter materials and testing requirements.
• Code Requirement: The NEC mandates the use of plenum cable in air-handling areas and restricts the use of non-plenum cable to other controlled environments.

In summary, plenum cable vs. non-plenum access control cable decisions should always align with local fire codes and project specifications. Safety and compliance (not price) dictate which one to use.

Code Compliance and Safety Standards

Cable ratings are derived directly from standards such as NEC Article 725 for power-limited circuits and NFPA 262 for flame and smoke testing. These guidelines are in place to reduce fire hazards and protect occupants in commercial buildings.

Using a non-compliant cable can lead to failed inspections, system removal, or worse, liability if a fire spreads through unapproved wiring. Municipalities may have local amendments to national codes, so confirming requirements with an authority having jurisdiction (AHJ) is always part of responsible design.

Plenum-rated cable adds a layer of protection in shared air spaces, reducing the risk of smoke migration through HVAC ducts. It’s an essential part of any safety-conscious building system.

Applications in Security and Access Control Systems

Different subsystems use cables with specific characteristics. In access control, access control wires power readers, locks, and sensors that control door operation. Many of these devices also use RS485 communication for data exchange, which benefits from shielded pairs to maintain clear signals.

When devices or control panels are located above ceilings where air circulates, plenum-rated security and access control cables become mandatory. For instance, an 18/2 shielded plenum cable may run from a controller to a card reader positioned in a plenum zone, offering both signal protection and fire compliance.

In contrast, non-plenum access control wires serve enclosed pathways, such as vertical risers between floors or behind protective walls. These cables are ideal for carrying control signals or power in areas that do not share airflow with occupied spaces.

Whether connecting cameras, controllers, or sensors, the right rating maintains both performance and safety compliance.

How to Select the Right Cable for Compliance and Performance

Selecting the correct cable starts with evaluating the environment and application. Follow a few guiding principles when determining what to specify.

1. Identify the Airflow Environment: Determine whether the cable route passes through air-handling spaces. If it does, a plenum-rated product is required.
2. Verify System Requirements: Consider voltage, shielding, and conductor size to ensure compatibility. For example, a 16 AWG wire might power a locking mechanism, while an 18/2 shielded plenum cable could carry both data and low-current power for a reader.
3. Check Regulatory Standards: Review NEC and NFPA references, along with any local building codes.
4. Balance Budget and Safety: Non-plenum options are appropriate for non-airflow environments, but fire-rated materials are worth the investment where safety demands them.

By understanding both the physical environment and system specifications, it’s easy to confidently select cables that satisfy inspection requirements and deliver long-term reliability.

Why Compliance and Quality Matter in Low-Voltage Cabling

Low-voltage systems depend on trust. Building owners, engineers, and contractors rely on wiring that performs safely over time. Using certified, properly rated cable protects people, property, and the integrity of the entire network.

Products should meet or exceed all national standards for plenum-rated security and access control cables, as well as non-plenum access control wires. For us, compliance isn’t optional. It’s built into how to approach every project. Quality cabling not only passes inspection but also ensures the stable operation of critical systems, such as fire alarms, cameras, and access control devices.

Making Informed Cable Choices

In the debate of plenum vs. non-plenum, there’s no universal answer. Plenum cables are designed for air-handling areas where fire and smoke risk is highest, while non-plenum cables are suitable for protected or enclosed pathways. Both play essential roles in a well-designed, code-compliant network.

Selecting the right access control cable isn’t just about performance; it’s about safety, compliance, and confidence in how your system operates.

To learn more about security and access control cable specifications, visit our Security & Access Control Resource Center. For assistance with selecting plenum or non-plenum cable options for your next project, contact our team.

Reliable low-voltage wiring forms the backbone of every professional security system. When selecting materials that strike a balance between performance and fire safety, it helps create environments that protect both people and technology.