Fireproof cables, which are widely used at this stage, mainly include UL series flame-retardant cables and flame-retardant low smoke halogen-free cables. The imported products are mainly from the Americas and Europe. Due to the incompatibility of fire-proof cable standards between the Americas and Europe, the fire prevention ideas are very different. Therefore, Party A and the design institute are in a passive state when selecting products, and each has its own reason. Finally, they often choose products according to the actual situation of capital.

UL flame retardant standards mainly include the following grades: cm, CMG, CMX.

1) pressurization level -cmp level (plenum flame test/steiner tunnel test)

The fireproof cable is the cable (plenum cable) with the highest requirements in the UL fire protection standard, and the applicable safety standard is ul910. The experiment stipulates that multiple samples are laid on the horizontal air duct of the device and burned with 87.9kw gas Bunsen lamp (300000btu/hr) for 20 minutes. The qualified standard is that the flame cannot extend beyond 5 feet from the front of the flame of the gas Bunsen burner. The maximum optical density is 0.5, and the maximum average density is 0.15.

This CMP fireproof cable is usually installed in the air return pressurization system used in the ventilation duct or air handling equipment, and is approved by Canada and the United States. Fep/plenum material conforming to ul910 standard has better flame retardant performance than low smoke halogen-free material conforming to iec60332-1 and iec60332-3 standards, and the concentration of smoke is low.

2) main line level - CMR level (riser flame test) this is a commercial riser cable in UL standard, and the applicable safety standard is UL1666. In the experiment, multiple specimens were laid on the simulated vertical axis, and the specified 154.5kw gas Bunsen lamp (527500btu/hr) was used for 30 minutes. The acceptable standard is that the flame cannot spread to the upper part of a room 12 feet high. There is no smoke concentration specification for trunk grade fireproof cables, which are generally used for floor vertical and horizontal wiring.

3) commercial grade - cm grade (vertical trail flame test)

Mineral insulated cable is a kind of cable that wraps copper conductor core wire with copper sheath and uses magnesium oxide powder as inorganic insulating material to separate conductor and sheath. The outermost layer can be selected with appropriate protective sheath as required. Commonly known as MICC or MI cable. There is a similar cable that uses metal instead of copper sheath to wrap the core wire and insulating material, which is called mineral insulated metal sheathed cable (MIMS cable).

In 1896, mineral insulated cables originated in Switzerland, spread to France in 1934, and began to develop in Britain and America in 1936. It is widely used due to its excellent fire protection characteristics, including the domestic test standard bs6387 for various mineral cables, which is also the British standard. Up to now, what we are talking about is rigid cable. After the introduction of mineral insulated cable into China, due to its high production cost, there were fewer manufacturers and users in the initial stage. Until the implementation of gb/t50016 in 2015, it was clearly required that MI cable be used for fire protection lines. So far, mineral insulated cable has ushered in the spring in China.

Mineral insulated cables can be divided into rigid and flexible types according to their structure. According to the standard, it can be divided into national standard cable (rigid) and enterprise standard cable (flexible). Rigid mineral cable has the old national standard, which is very difficult to bend as the name suggests, and has great limitations in transportation and installation. Flexible mineral cable rttz has the national standard gb/t 34926-2017, and other models have their own standards formulated by various enterprises. The standards of various manufacturers are different, and the quality is uneven.

There are only six types of national standard rigid mineral insulated cables: light load 500V bttq, bttvq, wd-bttyq, and heavy load 750V bttz, bttvz, wd-bttyz

Model of national standard flexible mineral insulated cable: rttz, rttyz, rttvz, voltage class: 0.6/1kv or 450/750v

The models of other flexible mineral insulated cables are named by each manufacturer. There are more than a dozen common types, such as btwtz, gan-btgyz, btly, ng-a, etc.