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What Is the Difference Between Plenum and Riser Cable?

Are you looking to buy the next ethernet cables but unable to differentiate between the plenum and the riser cables? Or you are a novice and can’t decide whether Cat6 Plenum is better for you or Cat6 Riser? You need not worry as we have got you covered.

Before going into the difference, let’s first know what plenum and riser cables are. 

What Is Plenum Cable?

A cable bearing a CMP mark on the outer surface of its jacket is characterized as a plenum cable. In case you are wondering, let us tell you that CMP stands for Communications Multipurpose Cable, Plenum, and it is the highest rating for jacket material for ethernet cables. These cables are meant for installation in the plenum spaces of the buildings. Plenum spaces are empty spaces between the ceilings or the floors of the buildings. These spaces are meant to facilitate air circulation for air conditioning and heating systems. These spaces are at greater risk of fire eruption, and this is where a plenum-rated comes in handy. 


The plenum cables are manufactured using supreme quality polyvinyl chloride. In case of fire eruption, these cables halt fire progression because of their fire-retardant properties. Also, when exposed to fire, these cables emit no smoke or dangerous gases. Because of the thick jacket, these cables provide top-notch protection against alien crosstalk, near-end crosstalk, and electromagnetic interference thus, keeping the integrity of your data intact. These cables are also UV resistant. The following types of plenum cables are available in the market right now: Cat5e Plenum, Cat6 Plenum, and Cat6a Plenum.

These cables, too, meet all types of industry standards, including FCC, CE, CSE, ISO/IES, and are in compliance with RoHS and TIA/EIA. 

What is Riser Cable?

A riser ethernet cable is identified by the CMR market printed on the outer surface of its jacket – CMR here stands for Communications Multipurpose Cable, Riser. The CMR-rated ethernet cables are also made using fine-quality polyvinyl chloride. As their name suggests, these cables are meant for installation in the riser or vertical spaces of the buildings.

Riser-rated cables also have fire retardant properties, and they too halt fire progression just like their plenum counterparts. When it comes to protection against electromagnetic interference, near-end crosstalk, and alien crosstalk, riser-rated have excellent protection against them. They, too, keep the integrity of your data intact. You can find the following types of riser cables in the market: Cat5e Riser, Cat6 Riser, and Cat6a Riser

These cables, too, meet all types of industry standards, including FCC, CE, CSE, ISO/IES, and are in compliance with RoHS and TIA/EIA. 

Difference Between Plenum & Riser Cables

  1. Jacket Material: The main difference between the riser and plenum ethernet cables is that of jacket material. Plenum cables enjoy CMP ratings. It is the highest rating when it comes to ethernet jackets. These cables are made from the best quality polyvinyl chloride. Riser cables come with CMR ratings, and it is the second-best jacket ratings in the ethernet cable industry. Although riser-rated jackets are also made from good quality polyvinyl chloride, the same is not as fine as it is in CMP-rated cables. 
  2. Irreplaceable: You can use plenum cables as a replacement for riser cables for installation in the riser spaces. However, you can’t use riser ethernet cables as a replacement for plenum cables. 


As far as specifications are concerned, like data transfer rates and bandwidth capacities, both riser and plenum ethernet cables share the same properties. For instance, a Cat6 riser cable will have the same data transfer speed and bandwidth capacities as are possessed by the Cat6 plenum. 

Terms to Know when Choosing Plenum Vs Riser Cabling

When shopping for plenum or riser rated cables, here’s a quick rundown of acronyms and other words to be aware of:

Cables with the letters CL, CM, and CMG. Residential-grade or general-purpose cabling is referred to as this. In Riser Or Plenum Environments, It Is Not Suitable For Commercial Use.

CMR Cables are a type of cable. Communications Riser. Approved for use in stairwells.

CMP Cables are a type of cable used to connect Plenum on Communications Approved for use in plenums and risers.

The National Fire Protection Association (NFPA) is a non-profit organization dedicated to preventing fires. The National Electrical Code was produced by this body.

NEC. The National Electrical Code (NEC) is a set of rules (NFPA 70). This guide is intended to establish a standard for electrical safety in residential, commercial, and industrial structures.

Plenum (CMP) Rated Cable VS Riser (CMR) Rated Cable

Plenum-rated cables are utilized in plenum spaces in business and residential buildings. These plenum spaces are found between the ceiling and the floor above it (drop ceiling), and they serve as conduits for heated/cooled or return airflows.

Plenum cables have a higher fire rating and are built with a low-smoke PVC or a fluorinated ethylene polymer fire-retardant plastic jacket (FEP).

In non-plenum regions, riser-rated wires run between floors through cable risers or elevator shafts. In a vertical burn test, these cables must also self-extinguish and prevent the flame from moving up the cable.

Riser cables are not subject to the same fire regulations as plenum cables. As a result, plenum cables can replace riser cables in plenum spaces, whereas riser cables cannot replace plenum cables.

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