Cat6 Plenum vs. Riser Cable: What are They and What's the Difference?

Updated on Sep 29, 2021 by

Cat6 Plenum vs. Riser Cable: What are They and What's the Difference?

For safety concerns, many users tend to buy flame-retardant cables, of which plenum rated cables and riser rated cables are the top two flame-retardant options that they may prefer to choose. Cat6 ethernet bulk cables are widely applied among all the ethernet bulk cables. So, what is the Cat6 plenum cable? What is the Cat6 riser cable? And Cat6 plenum vs. riser cable: What's the difference?

Flame Retardant Ethernet Cable Jacket Coatings

To know what Cat6 plenum cables (CMP) and Cat6 riser cables (CMR) are, it's essential to figure out the flame-retardant ethernet cable jacket coatings first. Presently, there are two principal types of flame retardant cables in use: PVC-coated Underwriters Laboratories (UL) cables, which adhere to US fire safety standards, and Low Smoke Zero Halogen (LSZH) cables, which comply with European fire safety standards. Cat6 CMP cables and CMR cables fall under the "UL cable type". This category encompasses a spectrum of cables classified into five safety and application-based standards: CMP, CMR, CM, CMG, and CMX.

Cat6 cable

What is a Plenum Cable?

Cat6 plenum cable is an ethernet bulk cable jacketed with improved low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer (FEP). The CMP cable (Communications Multipurpose Cable, Plenum) complies with the highest safety standard in UL fire protection standards-UL910 and is a flame-retardant cable.

Cat6 plenum cable can restrict flame propagation to no more than five feet and limit smoke emission when burned. Due to these characteristics, they are typically deployed in the air return pressure boosting system used in ventilation ducts or air handling equipment (above a suspended ceiling or under a raised floor, for example) and plenums, since they provide pathways for return airflows of buildings, facilitating air circulation. Moreover, less emission of smoke and toxic gases when burning reduces the damage to equipment and personal safety.

What is a Riser Cable?

Cat6 riser cable usually has a jacket covering made up of relatively inexpensive PVC. In other words, it has a higher halogen element content, and it releases a lot of smoke when it burns. Cat6 CMR cable (Communications Multipurpose Cable, Riser), is the commercial-grade cable in the UL standard, applicable to the UL1666 safety standard.

The Cat6 riser cables can be used anywhere except plenum space and air ducts and are typically installed between floors in non-plenum areas. It is the primary conduit of a building's distribution system, carrying voice, data, and video into the different spaces and levels of a building from the service entrance point. In both commercial and residential buildings, CMR cables are needed when running cable between floors through risers or vertical shafts.

Knowing what is a plenum cable and what is a riser cable, then, where does the difference between them lie?

Plenum vs. Riser Cable: What's the Difference

When talking about plenum cable vs. riser cable, there are four main differences.

Jacket Material: Cat6 CMP cable, made of low-smoke PVC or FEP, is chemical-resistant and supports -25 to 125 degrees Celsius. It's safer in fires due to lower toxin release. Cat6 CMR cable uses standard PVC which emits more smoke and toxins, and operates between 0 to 70 degrees Celsius.

Safety Standard: Fundamentally, Cat6 CMP cables and Cat6 CMR cables differ in safety standards. The former one meets the standard of UL910, which is the strictest standard, making plenum cables the most demanding. While, the latter one meets the standard of UL1666, not as strict as the former one. CMP cables have exceptional safety features.

Application: Cat6 plenum cables are used in plenum spaces and riser places. While riser cables can not be used in plenum spaces. Here is a picture of Cat6 plenum cable vs. Cat6 riser cable typical applications:

Plenum vs. Riser Cable Application

Cost: Cat6 Riser-rated cables are more cost-effective as compared to Cat6 plenum rated cables.

Check the chart listed below to get a clearer understanding of Cat6 plenum cable vs. Cat6 riser cable:

Cat6 Plenum Cable
Cat6 Riser Cable
Jacket Material
Low-smoke PVC or FEP
Safety Standard
Plenum Places
Riser Places
Cable Price
Costly than CMR
Less Expensive


For the plenum vs. riser cable, in conclusion, Cat6 plenum cables meet higher requirements in cable jacket material and safety standards, while Cat6 riser cables are cost-effective. CMP cable and CMR cable are both flame-retardant cables and have almost the same resistance against EMI and crosstalk. Knowing this, make your wise choice according to your actual needs.

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