The CMP vs CMR Cables: Difference Between Plenum and Riser Ethernet Cables

Choosing the right ethernet cables is an important decision that will affect your business for years to come. And that is  why we always recommend getting the right cables for your unique requirements. When you are getting new cables, you need to look at everything from the cable conductor to the resistance of the cable and from EMI to crosstalk.

In this article, we will discuss the difference between communications multipurpose plenum-rated cables and communications multipurpose riser-rated cables.

CM Cables

Communications multipurpose cables are used for connecting devices in a wired network, such as ethernet cables, coaxial cables, etc.  These cables are used widely in homes, schools, hospitals, offices etc.

CM Cable Jacket

It is a cable jacket that is specifically designed to meet the fire safety standards set by the national electrical code (NEC) in the article 800. Cables can heat up due to data transmission at extreme capacity or because of environmental conditions such as warm weather or high cable density and the risk of cables catching fire becomes higher.

To prevent such fire hazards, NEC has set a standard to ensure safety of infrastructure and life.

CMP Cables

CMP-rated cables are the safest of all communications multipurpose cables. They are designed for installations in indoor plenum spaces. What makes them even more popular is that they can be installed in any type of space.

For instance, you can run CMP cables in riser spaces or outdoors as well. But they can get a bit too pricey for that so mostly, in non-plenum spaces, either riser or PVC cables are installed.

CMP Cable Jacket

A CMP cable jacket is also referred to as a plenum jacket and the name comes from the fact that it is designed for installations in air ducts in indoor “plenum” spaces. For example, the raised floor or dropped ceiling in a building is a plenum space.

This jacket is the safest of all cable jackets. It is low smoke zero halogen (LSZH) insulation.

CMR Cables

Communications Multipurpose Riser rated cables are commonly referred to as Riser Cables because of the cable jacket and their application. These cables meet the NEC fire safety standards and are designed for use in indoor vertical rising spaces. For example, when you have to run a cable from one floor of a building to another, a riser cable is what you need.

These cables are to be used in enclosed spaces because in the unlikely scenario of catching fire, they can emit toxic smoke.

CMR Jacket

The jacket of the Riser-Rated ethernet cables is made out of a high quality PVC and is fire-retardant, just like its counterpart. It can withstand high-temperatures in all environments and has self fire extinguishing features. Meaning, it will prevent fires from spreading from one room to another.

Bear in mind, the likelihood of this jacket catching fire is very low, but it can emit toxic smoke if it does. And therefore, it is mandatory to run it only in enclosed spaces, when installed indoors.

Difference between CMP and CMR

Jacket Material: The material that is used to make both types of jackets is different. CMP jackets are made out of a low smoke zero halogen material (LSZH) and CMR jackets are made out of a high quality PVC.

Use: CMP cables are used in plenum spaces and CMR cables are used in riser spaces.

Cost: Riser rated cables are more affordable as compared to plenum rated cables.

Safety: Both cables are safe for use but CMP cables have exceptional safety features.

Resistance: Both jackets have almost the same resistance against EMI and crosstalk.

When to use CMP vs CMR Cables?

It goes without saying that both types of jackets are supposed to be used in different environments. Their recommended usage is to be followed strictly and doing otherwise may cause fire hazards. When you have to run cables in an indoor open space, you need to install riser jackets. For instance, if you are installing in the space above dropped ceilings, go get plenum-rated cables.

And if you are running cables in indoor spaces that are enclosed such as the inside of walls, you need to use riser-rated jackets.

Having said that, CMP jackets are not limited to only the indoor enclosed spaces. You can also use them outdoors and in riser spaces because they are the finest of all with the highest fire safety standards. However, using cables with plenum jackets in non-plenum spaces can be expensive as opposed to using non-plenum cables in non-plenum spaces.

CMP Cables Examples

The following are the examples of the most popular CMP cables that cater to all sorts of wired networking requirements from big industrial networks to small home networks.

  • Cat5e Plenum Cable
  • Cat6 Plenum Cable
  • Cat6a Plenum Cable
  • Cat7 Plenum Cable


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CMR Cables Examples

The following examples are the most popular riser cables and can be used in indoor riser spaces and even outdoors.

  • Cat5e Riser Cable
  • Cat6 Riser Cable
  • Cat6a Riser Cable
  • Cat7 Riser Cable

Why Smartech Cables?

For cutting-edge ethernet cables or accessories, check out Smartech Cables. We are the industry leader in manufacturing high-performance networking cables and accessories. Our products exceed the industry standards and we are offering market competitive prices, coupled with free shipping on orders above $100.