【 Weak current College 】 fire equipment selection of power supply cables and wires

Summary overview of the current fire equipment power supply wires and cables of the status quo, according to the standard describes the electric wire electric cable combustion characteristics of classification, fire-fighting equipment power supply cables and wires of provisions of the recommendation.
Keyword status characteristics taxonomy selection installation recommendations
First, the provisions relating to the specifications and status
National standards for the building design fire protection standard "GBJ16-87 (revised edition) 1A article 10.1.4, fire power equipment for power distribution lines should wear protective tube. When concealed should be laying in the non-burning body structure, its thickness should not be less than the downlead 3cm, must wear a metal pipe, and to take fire protection measures. Use insulation and sheath material for non-yanran cable can not take the wear metal pipe protection, but should be laying in cable well ditch.
Industry standard for the civil construction electrical design specifications "section 24.8.2 stipulates that: the power of super high-rise buildings, lighting, automation, and other lines use retardant wire and cable; but important fire equipment (such as fire pumps, fire service lift, anti, exhaust fan, etc.) of the power circuit, the use of fire-resistant cable. A class of high-and low-floor building of power, lighting, automation, and other lines use retardant wire and cable, but important fire equipment (such as fire pumps, fire service lift, anti, exhaust fan, etc.) of the power supply line, when you can use conditions to fireproof cable
Or adopt other measures to achieve fire-resistant wiring.
According to the Fire Department of statistics, China's a fire, electrical fire because of a half or so. And electrical fires because the electric wire electric cable of aging and overload caused by the use of a larger proportion of fire, a fire caused by the electric wire electric cable of combustible insulation and sheath material allows fire accident further expanded. Wire and cable insulation and sheath material combustion emit toxic gases causing large numbers of casualties, hampered Firefighters extinguish. At the same time, in a fire caused by the fire-fighting equipment of power supply line was burned, and cannot guarantee the normal operation of fire protection equipment,
Delay in the fire extinguishing time, causing greater damage to property. Due to architectural design fire protection standard is based on the level of economic development in China, so in the early 1990s to develop norms in the building on the equipment used and for fire fighting equipment used in wire and cable in use on did not make explicit provision. On the use of fire fighting equipment wire cable only take dark laying in the structure. And out of the fire for laying the measures requested are not clear, so that the designer cannot in wire and cable fire protection measures proposed for construction units on specific requirements. As China's economic development level, flame retardant, fire resistance, fire and other wire and cable have been successfully developed and put into production. I think it can and must the building wire and cable choice made explicit provisions to reduce the electric wire electric cable in occurrence of fire smoke and a variety of toxic gas that workers who were casualties, reduce the fire-fighting equipment power supply line of fire-extinguishing time delay to expand fire personal and property damage.
Second, wire and cable combustion characteristics of classification:
1. General Electric wire electric cable: no flame retardant, fire resistance, low smoke non-halogen and other features of wires and cables. General Electric wire electric cable uses organic materials as insulated and sheathed layer to flame ignition and spread in easily, without combustion characteristics.
2. flame retardant wire and cable, it is difficult to catch fire and prevent or delay the flame spread ability of wires and cables. Usually refers to pass GB/T18380.3 (same IEC60332-3) standard test qualified electric wire and cable. Flame retardant wire cable is not a noncombustible cable, it was only in the insulation and sheath layer added flame retardant materials, so that the cable is not in the fire, in an external ignition source yanran disappeared, after a period of time be self-extinguishing. But when external conditions change, in particular cable bunch of installation (that is, cable laying together), cable fire rather than because of self-extinguishing, interaction yanran cables.
Fire-retardant cables according to the adopted provisions of GB/T18380.3 different levels standard test, can be divided into A, B, C, D grade four kinds of flame retardant. Its requirements should be consistent with the requirements of the table 1. Table test capacity refers to the wires and cables into a vertical burning capacity of the cable, its method of calculation is as follows:
V=nS1－S2/1000
Type: n-cable sample number
S1-cable sample foreign section (mm2)
S2-cable samples of metal and in the area (mm2)
V — cable sample capacity of L/m
In the electrical design and use it should be noted that a general fire-retardant cables (ZR-VV, ZR-YJV) is not a noncombustible or retardant cable. In flame retardant cable selection should be noted that the cable of the flame retardant class.
3. fire resistance of wire and cable, in a specified temperature and time of the fire burning down can still maintain the integrity of the electric wire electric cable line. Usually refers to by GB/T12666.6 (equivalent IEC60331) test qualified electric wire and cable. Organic fire-resistant cable (NH-VV, NH-YJV) essentially follows the traditional cable manufacturing method, copper conductor for stranded wire, wrapping up a two-layer 50% cover of MICA fire zone (high temperature 800℃) as refractory layer, and then press a different model runs on a certain thickness of PVC or cross-linked polyethylene insulation for normal, last cable core fills between the outermost layer and rank-and-file cable sheath.
Fire wire cable according to the standards by GB/T12666.6 test, its request shall be in accordance with the table 2.
In the electrical design and use of, the General fire-resistant cable (NH-VV, NH-YJV) is not a noncombustible or retardant cable. In fact the cable outer sheath layer, fill the layer and the inner insulation, should belong to combustible or fire retardant materials. Fire-resistant cable's main function is sheathed layer, fill the layer within the insulating layer after the fire, the ablation by wrapping in copper conductors of MICA fire protection and continued on for some time, so the fire-resistant cable not the cable can fire, but only in the fire to maintain power on a period of time.
4. fireproof cable: cable with vast mineralEdge and copper, in flames with noncombustible performance and smoke-free, non-toxic, fireproof cables except by GB/T12666.6 (fire resistance test), but also has a certain resistance to spray water and resistance to mechanical impact. Fire-retardant cables is the use of inorganic insulation material cable, like magnesium oxide mineral insulated cable with solid round copper materials for conductors, surrounded by dense populated MgO powder for insulation, wall with copper pipes with special machines fill drawing moulding. Insulation material magnesium melting point up to 2800 ° c, melting point of copper, for 1083 ° c as long as they do not reach the melting temperature, copper mineral insulated cable is not damaged.
3. simulation entities fire test report
According to Zhejiang Jiuli fire-resistant cable co., Ltd., in order to test for fire-fighting equipment is usually selected cable and laying in the continuation of the entity the fire power supply capability. As well as the common cable in case of fire, the fire sprinkler and heavy objects fall cases can guarantee the power supply, also in order to provide a basis for design specifications. By Sichuan fire Research Institute and Liguria company sponsored do simulation entities fire test. In 2001, from 26 to 28 April completed a three-time trials. Test cable and the laying of the way see table 3.
Test the cable in addition to oxygen layer of fire retarding cable, are chosen by 15KW load.
Water-jet set: for the strip of water spray, set two places, just above the cable layout. Water estuary from cable 0.7m, two nozzle spacing 1.4m. Water pressure Jet pressure 0.1Mpa 0.25Mpa,. Place: heavy weights in two groups of 4, set just above the cable on the concave parts of floors. The quality of each group were 1.6Kg, 3.3Kg, 5.2Kg and whereabouts 7.5Kg, heavy objects, using artificial control height distance cable 1.1m whereabouts.
According to the test reports, cable failure record of fire-resistant table 4.
The impacted experiment records see table 5 and table 6 and table 7 for spray impact cable experiments records see table for eight, nine, ten tables table
IV. fire-fighting equipment selection of power supply cables and wires:
Currently in the country, has not yet developed flame retardant, fire resistance, fire-retardant cables and wires of product standards, all such cables and wires of naming is based GB12666.5-90 and GB12666.6 ~ 90 fire resistance test standards, as regards cable sheathing materials added a flame retardant and online-tied to the Mica, cable in the electrical performance of what changes have taken place without a clear in the standard.
The civil construction electrical design code JGJ/T16-92 the 24.9.6 section on various types of fire and electrical devices in a fire during a continuous period of at least the time of power supply, as shown in table 11. Canada national building code height is greater than the building, 18m should provide the full circumstances can work two hours of emergency power supply, alarm and communication system using a direct cable should be able to withstand fire attack 1 hour, Australia AS2293 standards require emergency evacuation lighting master feeder, the feeder cable run 2 branch hours, and the last branch circuit to achieve 15min. While the architectural design fire protection standard of fire power equipment for power transmission in the downlead must wear metal tube and fire protection measures. As for fire prevention measures can be standard specification does not clearly defined. I am of the view that, in order to meet fire safety equipment in the fires of continuous power supply, you must wire cable of the flame retardant, fire resistance, fireproof grade definition made clear on building wires and cables are categorized using the site, and expressly provided for in the specifications for various wires and cables of the use of environmental, fire protection equipment power supply line of wire and cable made of clear requirements.
For mineral insulated cable, because of its non-combustible, non-smoking, non-toxic and impact resistance, fire resistance of spray characteristics can be defined as fire-retardant cables.
For normal equipment of power supply lines, in Super high-rise building level can be used in A flame-retardant cable, in public buildings to use B-flame electric wire electric cable, other buildings can be C-level fire wire cable.
By substation (or total power distribution unit) to the main line of fire power. Super high-rise building and belongs to the doctrine of a class of high-rise buildings for fire equipment elevators, fire pumps, fans, smoke and fire control, fire emergency lighting line to use cable, other fire equipment, fire-resistant cables can be used.
Reference documents
1. simulation entities fire cable characteristics report Ministry of public security fire Research Institute in Sichuan province, Zhejiang Jiuli refractory
Cable Co., Ltd.
2. pay attention to the important part of the electric fire-line fire party pure soldiers