National Standard Specification for Fire Protection of Cables

Mentioned cable fire prevention, the industry often associates with the scene of laboratory combustion testing. Indeed, the delineation of the international standard in the fire rating of cables is mainly based on the test conditions of the spread distance, burning time, heat and smoke release, and gas toxicity release of the cable after ignition.

At the national standard level, corresponding explanations were also made on the fire protection of cables; on the other hand, the rapid development of data centers and smart buildings also required the domestic market to further regulate the level of fire protection cables to meet higher demands.

From international standards to national standards

As we mentioned in the previous series of articles, for the fireproof and flameproofing of cables, there are mainly international standards such as the UL series of the United States, the IEC 60332 series of the International Electrotechnical Commission, the EN 50399 and the EN 50265 series of the European Union. standard test.

In the United States, according to the UL series test standards, the cables are further classified into four levels: CMX (lowest level), CM, CMR (vertical use), and CMP (for forced ventilation). The details of the cables prevent flame spread. demand. Among them, the CMP grade cable has the highest flame retardant rating.

The above international standards are widely used in the cable market. In the process of revision of the GB/T 50311-2000 “Design Code for Integrated Cabling Systems for Buildings and Buildings”, China also incorporates the design and use of domestic buildings. Cable fire rating was introduced into national standards.

The national standard GB50311-2007, namely "the design specification of integrated wiring system engineering" is one of the most important national standards in the field of integrated wiring in China. In this specification, the “fire prevention” specification is specifically separated as a separate chapter and introduced in two parts, which indicates the importance of national standards for cable fire protection.

Among them, Section 8.0.1 stipulates that "according to the fire rating of the building and the fire-resistance requirements for the material, the cable selection and deployment method of the integrated wiring system and the installation site should take corresponding measures."

Here, the principle of adaptability of fire protection requirements for integrated wiring is emphasized, that is, the fire protection of cables must be matched with the fire rating of buildings. The so-called matching, in fact, it is recommended that when planning and designing a building, use a fire-resistant cable that is equivalent to or slightly higher than the fire rating of the building.

If the fire rating of the cable is not enough, not only can it fail to meet the fire protection requirements of the entire building, but it will also be a hidden danger of serious damage in the fire. Of course, a too high cable fire rating will increase the project cost. The main content of Section 8.0.2 is based on an equal comparison of European, American, and international cable testing standards, and then proposes facing different occasions and installation methods, using cables that meet the appropriate fire rating, several typical details as following:

When laying cables in vented spaces (eg in ceilings and under raised floors, etc.), CMP grades (OFNP or OFCP cable) or Class B1 can be used; trunk cables in cable shafts are open. When laying, CMR grade (OFNR or OFCR cable) or B2 and C grades can be selected; under the laying conditions of fireproof protection using sealed metal pipe slots, the cable can be CM grade (OFN or OFC cable) or D level.

It can be seen that the national standard is based on the reference to the international testing standards, and puts forward the requirements for matching and comprehensive consideration of the building fire rating, as well as the height, area, function, and importance of the building. Although the specific provisions are relatively simple, the importance of fire protection for cables has been pointed out, and it is of important guiding significance for the promotion of fire retardant cables in the domestic market.

Market philosophy needs follow up

Although GB50311 combined with the specific conditions of domestic building design and construction, the problem of cable fire prevention was explained. However, in a certain period of time, fire prevention cables did not attract sufficient attention in the domestic market. According to statistics, the total amount of domestic CMP cables is only a few thousand boxes per year, while in the global market, this figure is 200,000 to 300,000 boxes per month, and the usage is still increasing year by year.

In recent years, with the development of intelligent buildings and the rise of the data center cabling market, high-density cabling has become a trend. At the same time, the development of super high-rise buildings and the impact of several more serious fire accidents are also thought-provoking. As a building's underlying infrastructure, a high-grade flame-retardant cable emits fewer toxic and acidic gases when burned, and has less heat and smoke, for buildings, people, information, equipment, etc. Fire safety is crucial. Against this background, more and more domestic users and design agencies have given full attention to the problem of fire protection of cables. The application of high-grade fire-resistant cables, especially CMP grade cables, has gradually opened up in the domestic market. More and more domestic projects, especially data-centers, airports, hospitals, libraries, museums and other key fire protection units have also had CMP cable deployments. At the planning and design level of the project, users with long-term vision and design units are choosing high-grade fire-resistant cable products based on the needs of the industry and social development. In fact, in view of the market prospects of domestic high-grade fire-retardant cable, many suppliers are actively investing in production and R&D, and Wantai Technology, which focuses on CMP-grade cable production, is quite representative. The company has been investing in CMP cable production since 1998. Currently, it has deployed more than ten factories and R&D facilities in the world. The CMP flame-retardant cable output reaches 30,000 boxes/shaft per month, accounting for 10% of the total CMP cable production in the world. One of the strong.

Nowadays, it has been five years since the GB50311-2007 standard was formally implemented. The country has already passed the revision of this standard and will formally implement the new national standard in 2013. However, it is certain that the problem of cable fire protection will still be one of the key elements of the new national standard and will be more detailed. It can be expected that with the introduction of the new national standard, high-grade fire-retardant and flame-retardant cables will have better development opportunities in the domestic market.