The Difference Between CMP and CMR Network Cables

If you are in need of network cables for Internet or cable TV, you may be a little surprised to see all the different types of cables that are available. Deciding which type you need might be a bit challenging, especially if you are slightly unfamiliar with network cabling. The two main types of network cables include CMP and CMR. Each has its own uses, advantages, and disadvantages.
 

CMP Network Cables

CMP cables are plenum cables; these cables are used if networking must be done in air ducts. They can be used for commercial or residential spaces. Some people believe that these cables are not meant for residential (home) spaces, but they can be used if you must wire your home network through the air ducts (between the ceiling and the floor above the ceiling).

If you plan to run cable through air handling spaces, you will be required to use plenum cables as they will not combust and cannot actually cause fires. If the cable is in the path of a fire, it melts and emits very little toxic fumes, which is safer and healthier for people and animals that might have to breathe in smoke-filled air before removing themselves from the premises. Cables that must be run through air ducts (plenum spaces) must be proven to be fire safe in accordance with NFPA (National Fire Protection Association) 262.

Plenum (CMP) cable can use two types of fire-retardant plastic jackets.
 

Jacket Types	Specifications
Polyvinyl chloride (PVC)	Low smoke point Patented in 1987 Readily available for purchase Low to no toxins emitted
Fluorinated ethylene polymer (FEP)	Higher smoke point Never commercialized, so more difficult to find Can produce slight toxins when burned

There have also been efforts to develop a non-halogen plenum compound that would provide even better flame-retardant jackets.

CMP cable can be used in any area of the home, including running along baseboards and through rooms. Many cable companies recommend using CMP cables throughout the house as it is safer to use in case of fire, even though they are stiffer than CMR cabling and more difficult to bend. Types of CMP cable include R-733 and R-753.
 

CMR Network Cables

CMR cables are riser cable. These are used for regular networking 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. For example, if you drill a small hole in the living room floor, you can run a CMR cable into the basement.

These cables can be used for both commercial and residential spaces but are generally used more for residential homes. Fire requirements are less strict than with CMP cables, though they must still pass a vertical burn test to ensure they will self-extinguish and prevent the flame from moving up the cable.

Small spreading can occur with these cables, however, and they can emit toxic fumes when burning. This is considered to be a slight problem, but the amount that is breathed in during a fire is not enough to warrant consideration, as long as these cables are not used in air ducts.

Because there are less restrictive requirements on CMR cables, they cannot replace CMP cabling, even though CMP cabling can replace CMR type cabling. 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.

Types of CMR cables include R-731, R-751, and R-756. Both CMP and CMR cables come in a small variety of colors, making it easier to match with walls and flooring.
 

Other Types of Cables

Even though CMR and CMP cables are the main types, there are other types of cables that warrant some explanation.
 

Cable Types	Specification
UL Cable	Used for basic electrical wiring Available for use in appliances, LAN cable, optical fiber cables Must pass UL 1851 Vertical Tray Flame Test
CM Cable Other names can include CMG, CMX	General building wiring Must still pass the UL 1581 Vertical Tray Flame Test Types include R-732, R752, R-757

These cables are used for wiring the home for electricity, not for wiring home or business networks.
 

Conclusion

Deciding on the right type of cable for your home network is important; CMP cable is usually recommended, since it can be used for any type of cable needs. CMR cable is actually a great choice if you are not required to run cable through air ducts, as this type of cable is not up to fire standards in the use of air ducts. However, many homeowners are able to run cables without the use of air ducts, so this is a great choice.

It is also possible to replace any CMR cable with CMP cable, though you cannot necessarily replace CMP cable with CMR cable. These cables come in many different colors, which can help you "hide" the cables around the home.

The most recommended type of network cable is the CMP cable; this is recommended by cable companies and many individuals. It can allow peace of mind that if a house fire were to occur, the cables would not catch or spread the fire, and there would be less risk of toxic fumes being inhaled. CMR cable is also a great type of cable for normal home use, so it is completely a personal decision as to which type you choose, unless of course, you must run your cables through air ducts.

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