Ethernet cable jackets are made from various materials and carry with them different ratings assigned by the NEC. Let’s run through some commonly asked questions about these materials and NEC ratings to help answer which ethernet jacket type goes where in each installation:

What is a PVC jacket?

Polyvinyl Chloride is the backbone material in most ethernet cable jackets. It is a high strength and flexible material, which makes it a go-to jacket for most ethernet cabling. PVC is the most common material found in the below jacket ratings.

What about PE jackets? Where are they used? 

Polyethylene is most common with outdoor rated jackets. They are good at moisture and overall weather resistance. There is also a CPE jacket (Chlorinated Polyethylene), which is even better at oxidation, weather/UV, heat, oil, and flame resistance. PE is best used for any outdoor ethernet runs, while CPE is ideal for direct burial.

What is a CM rated jacket?

Communications Multipurpose. This is the “everyman’s” jacket. CM has some ability to prevent the spread of flame, specifically to the top of a tray in the Vertical-Tray Flame Test. This jacket type is fit for cable trays and other areas that are not classified as riseror plenum spaces. CM jackets are made from PVC. For easier identification, this type of jacket is mostly used “In-Room.”

Where does CMR rated cable go?

Communications Multipurpose, Riser. This cable is meant for installation in vertical shafts. CMR is made from PVC, but it is a grade of flame-retardance that prevents the spread of fire from one floor to another. CMR cable can be used as a substitute for CM, but it is not meant for plenum (air return) spaces. For easy identification, this cable is mostly used “In-Wall,” for vertical runs.

How do I know if I need CMP?

Communications Multipurpose, Plenum. This material burns clean, meaning it does not give off toxic fumes, and can also self-extinguish. PVC releases a thick, toxic smoke when burned, so CMP (plenum) jackets are made from low-smoke PVC, or fluorinated ethylene polymer (FEP). Making it the cable jacket for ethernet runs in a space used for air circulation by HVAC system, namely: a drop ceiling or raised floor.

Is LSZH the same as Plenum?

Low Smoke Zero Halogen is not the same as a plenum. LSZH cables are free from halogenic elements (fluorine, chlorine, bromine, iodine, and astatine). These elements are very common in PVC material, but are toxic when burned. LSZH cables are most often used in low ventilated areas. Think: airliners, railway, ocean liners, and submarines. The military is a major adopter of the LSZH standards, but this jacket rating is more common in Europe than the United States.

What is an Outdoor rated jacket?

Outdoor rated ethernet cables have either PVC or PE jacket that protects against UV rays, moisture, high/low temperatures (-40F to +140F), and some abrasion. Outdoor cable are obviously the best choice for outdoor, or partially outdoor, ethernet runs.

What is the difference between Outdoor and Direct Burial jackets?

Direct Burial jackets are typically made with either PE or CPE material and have been rated for insulation from water absorption and crush-resistance. In terms of jackets, outdoor and direct burial are similar, but the direct burial cables are filled with gel to prevent water from leaking into the cable. 

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