summary: Broadcast cable ratings It matters more than many installers realize. These ratings keep systems secure, code compliant, and ready for challenging broadcast environments. This guide explains the CMP, CMR, CL3P, and CL3R flame ratings, how they differ, and when each rating is required. You will also get a clear view Plenum versus riser cableEnvironmental needs and how to choose the right Remee cable for each installation.
broadcast Cable installation The facilities are filled with cables that run over ceilings, between floors, and through studios, control rooms and equipment racks. In the event of a fire, these cables can act as a fuel or conduit for smoke and flames if not properly rated. Fire resistant jackets and the correct code ratings are the first line of defense for occupants and equipment
Section 800 of the National Electrical Code (NEC) specifies communications cable ratings as CMP and CMR, while other NEC articles specify Class 2 and Class 3 limited-power ratings (including CL3P and CL3R). These ratings apply to the enclosure, not to bandwidth or signal performance, but define where cable can be legally and safely installed within a building.
Broadcast cable ratings: CMP, CMR, CL3P, CL3R
All of these common classifications appear in streaming, AV, and IPTV installations, but each serves a distinct purpose. Understanding them helps ensure that the Remee cables you choose comply with the environment and local AHJ (authority having jurisdiction) expectations.
CMP (Communications Plenum)
Highest rated standard communications jacket for indoor use
Intended for ducts, rooms and other air handling spaces (for example, above suspended ceilings used for return air).
CMR (Communication Riser)
Elevated communications cable for vertical columns or rising spaces between floors
Designed to limit the vertical spread of flame so that flames from one floor do not quickly move to other floors
CL3P (Class 3 Plenum)
Category 3 full area power limited cable, used when the circuit carries a higher voltage than Category 2 while still being power limited.
It must pass more stringent flame and smoke tests, which are similar in concept to the CMP test but for circuits with limited power rather than just communications.
CL3R (Class 3 Riser)
Power-limited Category 3 cable approved for riser spaces between floors
Not acceptable in public, but suitable for vertical risers and many power-limited in-wall broadcast applications.
In general, higher-rated (full) jackets can replace lower-rated (higher or general-purpose) environments, but not the other way around. For example, CMP or CL3P can be used in risers, but CMR or CL3R cannot be used in plenums.
Plenum vs Riser Cable in streaming facilities
Plenum vs Riser cable It is one of the most important differences between broadcast engineers and installers who work in multi-floor or commercial spaces. Plenum cable is required wherever the cable is installed in an air handling space, while riser cable is intended for vertical runs between floors.
Plenum vs Riser Cable: Understanding the Key Differences in Streaming Applications
location
Plenum: Air handling spaces such as suspended ceilings for return air or raised floors used for heating, ventilation, and air conditioning (HVAC) circulation.
Riser: Vertical columns, sleeves, or channels connecting multiple floors (for example, MDF to IDF to studios).
Fire and smoke performance
Plenum (CMP/CL3P): Should limit flame spread to a short distance, produce low smoke and reduce toxicity.
Riser (CMR/CL3R): Tested for vertical flame spread but with less stringent smoke and toxicity requirements.
For broadcast applications, choosing the right cable or Remee ClearCast riser cable helps protect air continuity and conforms to building and fire codes, especially in large venues such as arenas, convention centers and studios.
CMP vs. CMR Cable: How to Choose for Each Installation
to understand cmp vs cmr cable In context makes code decisions easier during design and installation. The following simplified scenarios illustrate where each classification is typically needed.
Use CMP (or CL3P) when:
Run broadcast signal or control cables into ceiling air handling spaces across studios or open office areas
Routing camera, intercom, or IP audio cables through air return paths in large production facilities or houses of worship.
Use CMR (or CL3R) when:
Run vertical supports between floors, from central art spaces to remote studios or rack rooms
Installing riser feeders for IP distribution, IFB or control networks in non-air handling columns or vertical ducts.
Because the jacket rating does not affect bandwidth, a Remee ClearCast™ cable with a CMP jacket will have similar electrical performance to a CMR version of the same construction, changing the fire and smoke behavior of the jacket material.
If you are not sure what classification your application needs, you can contact Remee technical specialists through the link Ask an expert Interface to review floor plans, local code requirements and environmental conditions before selecting a product.
The main differences in installation
Environmental considerations for broadcast cable installation
The physical environment affects cable selection as much as it does flame rating. Broadcast systems operate across a variety of conditions from hot mechanical rooms to outdoor broadcasts. Remee designs cable jackets and shielding to support these environments.
Key environmental points:
Internal relocation versus external relocation
Use appropriately rated, UV- and moisture-resistant outdoor jackets or OSP when leaving the building envelope, and transitioning to CMP or CMR indoors.
Temperature and mechanical stress
Avoid exceeding bending radii, tensile loads, or temperatures, especially around cameras on booms, stage boxes, or mobile production vehicles.
Low toxicity and smoking options
In high-occupancy settings (broadcast studios, theaters, stadiums), low-smoke, low-toxic vests help reduce risks during evacuations.
Selecting the correct rating of your broadcast cable (CMP, CMR, CL3P, or CL3R) is non-negotiable for code compliance, installation safety, and uninterrupted AV performance. With Remee’s full range of ClearCast™ cables designed for every environment, you can install with confidence and peace of mind.
You have a project with unique Cable installation Needs or strict code requirements? If the level of Remy Clearcast™ cables not suitable for need, Order a new custom cable.
Frequently Asked Questions: Broadcast Cable Evaluations and Installation
Q1: How do broadcast cable ratings affect code compatibility?
A: Authorities having jurisdiction (AHJs) and building inspectors rely on markings such as CMP, CMR, CL3P, and CL3R to quickly verify that installed cabling conforms to the type of building space. Using a low-rated cable where a higher rating is required can result in failed inspections, rework costs, and increased life safety risks in the event of a fire.
Q2: Can full cable be used everywhere in a broadcast facility?
A: Fully Rated Communications Cables (CMP) and Category 3 Cables (CL3P) can generally be used in riser and in-wall applications, making them an effective alternative to CMR and CL3R in many cases. But the opposite is not allowed; CMR or CL3R cable cannot be installed in plenum air spaces unless it is enclosed in approved metal conduit that meets code.
Q3: How do full cabling versus riser cabling options affect cost?
A: CMP and CL3P cables tend to be more expensive because they use high-performance, low-smoke flame retardant materials and undergo more stringent testing. Therefore, many broadcast projects use a mix: full cabling where needed and uplink cabling elsewhere, to balance safety, compliance and budget.
Q4: How do CL3P and CL3R fit into broadcast system design?
A: CL3P and CL3R apply to power-limited Class 3 circuits, which are common in some low-voltage audio, control, and power applications in audio, video, and broadcast systems. CL3P should be used where these circuits enter plenum spaces, while CL3R is used for riser applications or interior passages between floors that do not process air. When both communications and power-limited circuits share the same path, each cable must carry a rating appropriate for that environment.
