What is the difference between CM CMR CMP fire ratings?

CM, CMR and CMP are three different fire ratings in UL safety regulations, and there are obvious differences between them in terms of fire performance, application places and price.

First of all, CM fire rating is the fire rating for ordinary data cables, which are generally used in ordinary homes and general offices. Its flame retardant effect is realized based on halogenated chemicals, and the outer sheath is mostly made of PVC and the insulation layer is made of high-density PE. When burning, it will emit toxic halogens, smoke, and release a large amount of heat.CM grade cable netting in the combustion spread less than 5 meters will be automatically extinguished.

Secondly, the safety of CMR fire rating is located in the second, mainly by improving the ignition point of the cable to achieve the purpose of not easy to burn. The test standard is UL 1666, in the fan forced combustion conditions, a bundle of CMR cable must be in the combustion spread less than 5 meters within the self-extinguishing. CMR grade cable network cable outer jacket is made of high flame-retardant PVC material, the insulation layer of high-density PE material, encountered in the flame combustion, it will be emitted toxic halogenated gases (chlorine) and lead vapors. CMR grade cable network cable is widely used in ventilation systems in trunking applications that are physically separate from the cabling system, commonly found in regions such as Asia and Australia.

Finally, the CMP fire rating is the highest fire rating in the UL Fire Rating Standard. It is higher than the IEC 60332-1 and IEC 60332-3 standards for flame retardancy, and is commonly used in large data centers, media centers, financial centers, convention centers, museums, and other venues in the building.CMP-rated network cable insulation materials use the U.S. DuPont Teflon FEP (perfluoroethylene propylene copolymer), which is highly ductile, highly flame retardant, and other characteristics. According to UL standards, CMP fire-rated cable combustion, the fire spread distance can not reach beyond 1.5 meters.

When choosing CM, CMR or CMP cable network cables, you need to consider the specific application scenarios, safety needs and budget. Generally speaking, ordinary homes and offices can choose CM grade cable network cable, while for places that require higher fire safety, such as data centers or large public facilities, you should choose CMR or CMP grade cable network cable. It is also important to ensure that the selected cable network cables comply with relevant international standards and codes to ensure their quality and performance.

In addition, attention should also be paid to checking the outer jacket marking of the cable to ensure that it is labeled with words such as ISO/TIA, PVC/LSZH, and CM/CMR/CMP, which are important references for determining the performance, material, and fire protection rating of the cable. If there is no such marking, the theory suggests that the material of the cable, fire resistance is poor, and does not meet the international standards for integrated cabling and wiring, the use of such cables may appear network barriers or security risks and other issues.

CM CMR CMP fire ratings
CM CMR CMP fire ratings

After the above introduction, you must have found the differences between CM/CMR/CMP in terms of fire rating, burning conditions and outer jacket materials. In addition, there are also differences in price, application areas, substitutes and so on.

  • Price difference
    As the outer sheath of CM Cable Network Cable and CMR Cable Network Cable is made of PVC material, while CMP Cable Network Cable is made of fluorine material, the price of CM Cable Network Cable and CMR Cable Network Cable Cable Cable is cheaper than that of CMP Cable Network Cable.
  • Different areas of application
    In general, CM Cable is used for building elevators, inflatable rooms other than other environments in the media and horizontal cabling. CMR is used for vertical cabling in building elevators and vertical passages. CMP is used for air ducts, inflatable rooms or other air. Horizontal wiring in circulation environments.
  • Substitution
    In general, CM cable network cable cannot replace CMR cable network cable and CMP cable network cable.

How to choose CM/CMR/CMP cable network cable?
From the above, it can be seen that the fire rating CMP>CMR>CM. so is it not the most suitable to choose CMP cable in the actual application?
Relatively speaking, CMP cable network cable is a good choice. Since CMP cables have the highest fire rating and safety and are suitable for any type of cable and network cable requirements, the risk of inhaling toxic fumes if a fire accidentally breaks out in a building is relatively low. However, given the cost, it is not necessary to choose CMP cable networking cables for data center cabling, such as vertical trunking systems. Ductless cabling is now possible in most data centers. Therefore, CMR cable network cable is also a good choice.

Related Knowledge Answers
What are PVC, LSZH, OPNR and ONFP?

These are cable fire ratings and outer jacket materials. Fiber optic cables also have specific fire ratings (OFNP/OFCP/OFNR/OFCR). They are more flame retardant than CMR/CMP copper cables. For more information, please visit “Characterization of various types of fire retardant cables“.

Sheath Material Advantages
PVC (polyvinyl chloride) cable:

Good mechanical properties, high electrical insulation, flexible, strong, good flame retardant, but less stable to light, heat, so more suitable for indoor fiber optic cables. Outer sheath material.

LSZH (Low Smoke and Halogen Free) cable:
It is characterized by low smoke, low toxicity, low corrosion and high flame retardant. As a safe and environmentally friendly material, LSZH is ideal for indoor/outdoor installations; however, it is more expensive.

Plenum is one of the main components of OFNR grade fiber optic cable. It is highly flame retardant and does not produce toxic or corrosive gases at extremely high temperatures. Fiber optic cables made from Plenum are the preferred choice for wiring in ventilation ducts used in air handling equipment or in air recirculation pressurization systems.

Risers are one of the main components that form OFNR-rated fiber optic cables, which are less flame retardant than the Plenum material and have a lower flame retardancy than the Plenum material.
Plenum material is weaker and is a non-toxic, corrosive gas specification. Therefore, OFNR grade fiber optic cables with Riser material are usually used to build trunk and horizontal cable network cables.

OFNP/OFCP NEC standard flame retardant grade (pressurized grade), the highest grade. Assuming that a fan is used to force a flame onto a bundle of flame-retardant (pressurized) fiber optic cable, the flame on the fiber optic cable will extinguish itself within 5m and a non-toxic, non-corrosive gas will Being generated.

The OFNR/OFCR NEC standard has the second highest vertical level (trunk level). Again, a fan is used to force the flame onto the trunk level fiber optic cable bundle. There are no smoke or toxicity specifications, although the flame will extinguish itself within 5m of spread.

TST CABLES – Leading Global Supplier of High Temperature Fire Resistant and Flame Retardant Cables
TST CABLES specializes in providing high temperature fire retardant cable applications and solutions, we for the railroad, aviation, marine, nuclear power, oil and gas, wind power and other industries, to provide a variety of specifications for the manufacturing process of fire-retardant cables, the cable material selection need to undergo a rigorous design and testing, to ensure that the cable in the normal operation and the fire, high temperature and other extreme conditions of safety and stability. When choosing fire protection cables, the most suitable product should be selected according to the specific application scenarios and needs, taking into account the performance, safety, cost and other factors of the cable.

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