Jacket Types for Ethernet Cables (CMP, CMR, CMX)

The internal wires of an Ethernet information link are protected by a coat, which is an exterior sheath. This coat is available in a variety of colors and styles to suit a variety of needs. Ethernet cable coatings are made from a variety of materials and carry a variety of NEC assessments. Because there is no such thing as a one-size-fits-all Ethernet or outdoor cable, selecting the right one might be challenging.

Jacket Types for Ethernet Cables

Choosing between CMP, CMR, and CMX cables is one of the challenges you may face. NEC (National Electric Code) kinds are the acronyms listed above. The National Fire Protection Agency of the United States created the code to specify the different types of cable jackets and their uses. The outer wrapping of an Ethernet cable is called a jacket, and it protects the interior wires.

So, what’s the difference between jacket Types for Ethernet Cables? This page defines this terminology and explains the Facts About CMR, CMP, and CMX Ethernet Cable Jacket.

CMP (Communications Multipurpose Cable, Plenum)

Communications multipurpose cable plenum, or CMP, is defined in Article 800 of the National Electric Code as a cable with a fire-resistant rating jacket, also known as a plenum-rated cable. The Ethernet Cables 1000ft CMP is designed to limit the spread of flame from a fire to five feet or fewer, hence lowering the amount of smoke created.

The plenum is defined as a restricted region with a higher air pressure within than outside. It’s a distinct area that’s utilized for heating, ventilation, and air conditioning. In most buildings, space is found between the structural ceiling and the drop-down ceiling or under a raised floor. Such openings allow air to circulate throughout structures.

As a result, if the wires we employ catch fire, they must not emit harmful vapors. When exposed to fire, plenum-rated or CMP cables are made of FEP (fluorinated ethylene propylene), which melts fast and creates little smoke with less toxicity. They also burn smoothly and self-extinguish rapidly.


  • Although plenum cables are more expensive than non-plenum cables, they may be employed in residential and commercial areas in buildings.
  • Plenum-rated cables, rather than simple PVC cables, are required in places like air ducts. In the case of a fire, they will not burn.

CMR (Communications Multipurpose Cable, Riser)

CMR cables, in contrast to CMP cables, are known as riser-rated cables. The CMR cable jackets are composed of PVC with a Teflon coating to prevent them from catching fire. These wires are designed to keep the fire from spreading between floors through vertical shafts or risers. They are commonly used in traditional networking because, unlike CMP cables, they do not pass through an air duct.

Furthermore, the ultimate goal of its fire-repelling property is to prevent flames from spreading from one floor to another that are unaffected. Because CMR cables have substantially stronger fire resistance than CM cables, they can be used as a replacement in situations where CM cables are employed. CMR cables are more flame-resistant than CM cables and consequently cost more.


  • CMR cables are favored over CMP cables because they are less expensive, provide some fire protection, and are thinner, making them easier to terminate. 
  • They’re best used in riser ducts that run vertically between floors and inside walls. They can also be utilized in traditional networking for room-to-room applications if they do not travel over the plenum.

CMX Cable (Outdoor/Residential Communications)

Due to its UV resistance and weatherproof qualities, Cat6 Ethernet Cables 1000ft CMX rated are manufactured of LLDPE (Linear Low-Density Polyethylene). They’re designed to endure direct sunshine, wind, rain, and temperature extremes. They are not, however, fire-resistant.

Outdoor cabling in the open air or subterranean burial requires CMX-approved cables. They’re frequently utilized outdoors, in both business and residential buildings, to deliver the principal network/Internet connection, which may then be dispersed further. They can also be employed in regions where only a few communication wires are required.


When compared to CMR, CM, or CMP cables, CMX cables offer a higher level of resilience and impact resistance. 

The CMX is the finest choice, whether buried underground or mounted on the side of buildings.


Nabeel is an SEO and Content Marketer at Tantumtech.net, specializing in technology topics. With a profound interest in all things tech-related, he channels his enthusiasm into creating engaging and informative content. Nabeel's writing is focused on delivering valuable insights to readers, ensuring they stay up-to-date with the latest advancements and trends in the tech industry.

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