This white paper discusses telecom cable ratings, specifically CMP (plenum) and CMR (riser) cables, including their characteristics, applications, and fire safety standards. CMP cables are fire-retardant and suitable for air-handling spaces, while CMR cables are more cost-effective and easier to install for non-plenum areas. The document emphasizes the importance of selecting the right cable type based on specific installation needs and offers insights on the potential downsides and advantages of each cable type.

1. WHITE PAPER
FS.COM White Paper | Telecom Cable Rating: CMP or CMR Cables
We usually use terms—CMP, CMR, PVC and LSZH to describe telecom cables, but do you know what
these terms really mean? And, more importantly, which one does your project actually need? The
article below will briefly outline many industry cable types, along with their features to help you
have a better understanding of them.
Plenum Rated Cables
CMP cable refers to the communication plenum cable that is laid in the plenum spaces of buildings.
Plenum rated cable or just plenum cable is jacketed with a fire-retardant plastic jacket of either a
flame retardant low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer (FEP). Owing
to its material in this network cable, it doesn’t emit a toxic smoke when they burn. Plenum rated
cables are slower to burn and produce less smoke than other cables.
As seen in the above image, plenum refers to the air handling space. In a standard commercial
building, the plenum is the space between the drop ceiling and the structural ceiling. In residential
installations the plenum may include the space above the ceiling or under the floor when floor level
air circulation is used. Plenum rated cable is mandated to be installed in any “air handling” space
because of its low smoke and low flame characteristics.
Telecom Cable Rating:
CMP or CMR Cables

2. WHITE PAPER
FS.COM White Paper | Telecom Cable Rating: CMP or CMR Cables
Riser Rated Cables
CMR cable refers to the communication riser cable that is run between floors in non-plenum areas.
The term ”riser” usually refers to a space that runs between floors in an office or a commercial
building. The fire requirements on riser cable are not as strict as plenum cables. It will emit toxic
fumes when burning. This is considered to be a slight problem, but it is not enough to warrant
consideration as long as these cables are not used in ducts.
These cables can be used for both commercial and residential spaces but are generally used more
for residential homes. For example, riser cables can be used from room to room, as long as it is run
around baseboards, along bottoms of walls, and along the tops of walls. They can also be used to
run cables from the basement to the upper floor, as long as the cable does not need to pass through
an air duct.
How Do I Know Which One Should I Choose?
Many customers has asked about this question, unfortunately we cannot help or advise you as each
individual cabling details has to be evaluated. However, for those who plans to wire their house with
cat 5e or cat6 cables, we do have some practical suggestions for you to choose between plenum
and riser rated cables.
Both plenum and riser cables commonly include a rope or polymer filament with high tensile

3. WHITE PAPER
FS.COM White Paper | Telecom Cable Rating: CMP or CMR Cables
strength, which helps support the weight of the cable when it is dangling in an open chute. Cables
like twisted-pair, coaxial, HDMI, and DVI are available in both plenum and riser versions. The cable
cost is often significantly higher than general-use cable due to the special restricted-use flame
retardant materials. Plenum cable is expensive, much more expensive than riser rated cable.
Additionally the practice of running cables in plenum spaces is becoming less popular, and therefore
demand for plenum rated cable is much less than riser rated cable.
However, the plenum rated cables have a higher fire rating than riser cables. Thus, plenum cable can
always replace riser cable, but riser cable cannot replace plenum cable in plenum spaces. The
stiffness of CMR cable is less than that of CMP cables. This means CMR cable is easier to bend
around corners of baseboards and ceilings. This can allow a tighter fit against corners to minimize
the look of cables. The following two pictures shows the burning test of these two cables.
One final tip to keep in mind is that If you will never need to run it through air-handling
ducts/spaces, just get Riser rated. But, for retrofits, that's often the easiest route from basement to
the upper floors and sometimes a few basement ceiling joist spaces are covered over with tin to use
as inexpensive cold air return ducts. If you have to go through those, Plenum rating is required, too.
If there's ever a hot enough fire to melt CMR's covering, any toxic fumes it might emit will be among
the least of your worries. but the Riser rating means its fire-resistance will keep the flames from
following it between floors.

4. WHITE PAPER
FS.COM White Paper | Telecom Cable Rating: CMP or CMR Cables
Conclusion
Selecting the right type of cable for your home network is important; CMP cable is usually
recommended as it is safer to use in case of fire, even though they are more expensive and stiffer
than CMR cabling and more difficult to bend. But if you are not up to run cables through air duct,
CMR cable is actually a great choice, as this type of cable is less expensive and easy to install in a
network. FS.COM is committed to offer the most cost-effective cabling solutions to our clients. Our
cat 5, Cat 5e, cat 6 cables are available in both plenum and riser version. If you have any interest,
please feel free to contact us.

5. WHITE PAPER
FS.COM White Paper | Telecom Cable Rating: CMP or CMR Cables
Contact Us
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Notice: This document is for informational purposes only and does not set forth any warranty, expressed or
implied, concerning any equipment, equipment features, or service offered or to be offered by FS.COM.
FS.COM reserves the right to make changes to this document at any time, without notice, and assumes no
responsibility for its use. This information document describes features that may not be currently available.
Contact a FS.COM sales team for information on feature and product availability.
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