PVC vs. Plenum vs. Riser: Mapping The Differences
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PVC vs. Plenum vs. Riser: Mapping The Differences

Communication cables in a building are often referred to as plenum, riser, or simply PVC. Read this blog to learn how these three compare. Read this blog to learn how The standards of cables for riser and plenum spaces are regulated by the National Electrical Code and the NFPA National Fire Protection Association standards.

What is a PVC Cable in the Context of Plenum/Riser Characteristics?

PVC refers to the cables that are not rated for plenum or riser. These are the cables with a standard PVC polyvinyl chloride insulation. While PVC cables are of high quality and are optimal for many different environments, they are not rated for plenum and riser. Therefore, another way to put it is that PVC is a non-plenum non-riser cable. If put into places designed for plenum or riser cables, PVC cable is at risk of catching fire, quickly spreading it, and spreading gasses while it burns. All in all, cable with only a PVC rating cannot be used in tight places between the floors and air ducts because it would significantly risk a fire.

What are Plenum-Rated and Riser-Rated Cables?

Plenum-rated cables are specifically ranked for plenum spaces. Plenum spaces are air-filled parts of the building. For example, this is the part of the building where the air is circulated for air-conditioning systems and any ventilation. The cable that is rated for plenum can be used in air-tight places. The plenum-rated cable has excellent resistance to fire. While this does not necessarily mean that it is utterly immune to catching fire, it means that the cable will melt without spreading fire. Plenum cables will also not emulate harmful gasses as PVC cables would. Though not necessarily, plenum cables often have Teflon FEP analysis.

Сables that are rated for plenum are called CMP.

Riser-rated cables are radically different from plenum-rated and PVC cables because they are designed for riser spaces. Riser spaces are the places that are basically a shaft located vertically. All or most utilities within the building, including the electrical conduit and water supply, are distributed vertically within the riser. In simple words, risers are placed between the floors.

Cables rated for riser are called CMR, which is basically the name of their rating. These cables meet the fire standards of being installed between floors in the so-called non-plenum spaces. 

How Do Plenum and Riser Cables Compare?

Both plenum and riser cables (CMP and CMR) are fire-resistant cables with excellent performance in their respective places. If we compare plenum-rated cables to riser-rated cables, the fire resistance of the former is way superior. This difference does not really have any practical significance as the plenum and riser are not usually in one place. For the reason discussed above, a plenum cable is usually more than 50 percent more expensive than the riser cable.

Can I Use Plenum Instead of Riser and Vice-Versa?

Riser cable can never be used instead of plenum cable because it is not prohibited in plenum spaces. On the other hand, plenum cables can be used instead of the riser. 

For excellent communication cables, including plenum, riser, and PVC, shop at Nassau National Cable.

Communication cables in a building are often referred to as plenum, riser, or simply PVC. Read this blog to learn how these three compare. Read this blog to learn how The standards of cables for riser and plenum spaces are regulated by the National Electrical Code and the NFPA National Fire Protection Association standards.

What is a PVC Cable in the Context of Plenum/Riser Characteristics?

PVC refers to the cables that are not rated for plenum or riser. These are the cables with a standard PVC polyvinyl chloride insulation. While PVC cables are of high quality and are optimal for many different environments, they are not rated for plenum and riser. Therefore, another way to put it is that PVC is a non-plenum non-riser cable. If put into places designed for plenum or riser cables, PVC cable is at risk of catching fire, quickly spreading it, and spreading gasses while it burns. All in all, cable with only a PVC rating cannot be used in tight places between the floors and air ducts because it would significantly risk a fire.

What are Plenum-Rated and Riser-Rated Cables?

Plenum-rated cables are specifically ranked for plenum spaces. Plenum spaces are air-filled parts of the building. For example, this is the part of the building where the air is circulated for air-conditioning systems and any ventilation. The cable that is rated for plenum can be used in air-tight places. The plenum-rated cable has excellent resistance to fire. While this does not necessarily mean that it is utterly immune to catching fire, it means that the cable will melt without spreading fire. Plenum cables will also not emulate harmful gasses as PVC cables would. Though not necessarily, plenum cables often have Teflon FEP analysis.

Сables that are rated for plenum are called CMP.

Riser-rated cables are radically different from plenum-rated and PVC cables because they are designed for riser spaces. Riser spaces are the places that are basically a shaft located vertically. All or most utilities within the building, including the electrical conduit and water supply, are distributed vertically within the riser. In simple words, risers are placed between the floors.

Cables rated for riser are called CMR, which is basically the name of their rating. These cables meet the fire standards of being installed between floors in the so-called non-plenum spaces. 

How Do Plenum and Riser Cables Compare?

Both plenum and riser cables (CMP and CMR) are fire-resistant cables with excellent performance in their respective places. If we compare plenum-rated cables to riser-rated cables, the fire resistance of the former is way superior. This difference does not really have any practical significance as the plenum and riser are not usually in one place. For the reason discussed above, a plenum cable is usually more than 50 percent more expensive than the riser cable.

Can I Use Plenum Instead of Riser and Vice-Versa?

Riser cable can never be used instead of plenum cable because it is not prohibited in plenum spaces. On the other hand, plenum cables can be used instead of the riser. 

For excellent communication cables, including plenum, riser, and PVC, shop at Nassau National Cable.

Vita Chernikhovska profile picture

Author Bio

Vita Chernikhovska

is a dedicated content creator at Nassau National Cable, where she simplifies complex electrical concepts for a broad audience. With over a decade of experience in educational content and five years specializing in wire and cable, her work has been cited by authoritative sources, including the New York Times. Vita's popular series, such as 'What is the amp rating for a cable size' and 'How to wire different switches and appliances,' make technical information accessible. She also interviews industry professionals and contributes regularly to the wire and cable podcast.

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