JW-NHMA-III Fire-Resistant Aluminum Alloy Busway
I. Product Overview
The 180-minute fire-resistant aluminum alloy busway product is a specialized busway dedicated to powering fire-protection equipment. After years of testing, Jiuwei Busway became the first aluminum alloy fire-resistant busway product in China to pass type testing at the China Quality Certification Center and obtain CQC certification. It is suitable for AC 50Hz, three-phase four-wire and three-phase five-wire power distribution systems with a rated voltage below 690V and a rated operating current from 250A to 5000A. In addition to the standard conductive function of ordinary busway, the product must also maintain circuit integrity for a set period of time while exposed to flame. Its performance complies with the national standard GB/T 7251.6 and the relevant provisions of GA/T 537-2005 "Test Methods for the Flame-Retardant, Fire-Protective, and Fire-Resistant Performance of Busway Trunking Systems," achieving a fire-resistance time of 180 minutes
. The product can be used continuously both under normal conditions and for the specified duration in a fire environment, and is suitable for locations with high fire-protection requirements — such as super-tall buildings, large commercial complexes, metro transit hubs, airport terminals, key control centers, hospitals, and data centers — where it takes over power transmission and distribution duties in place of fire-resistant cables. Per relevant fire codes, fire-resistant busway should be used for a high-rise building's vertical fire-protection distribution trunk when the calculated current is 400A or above.
This product uses an aluminum alloy conductor. Aluminum has a density of only 2.7 g/cm³ — about one-third that of copper — so a busway of the same length is substantially lighter, making transportation and installation more convenient and significantly reducing construction cost and installation difficulty. Against a backdrop of persistently high copper prices and sharply rising budgets for electrical engineering firms, Jiuwei's alloy fire-resistant busway is an option that maintains electrical performance while significantly lowering cost, and it has already been applied on key national engineering projects
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II. Core Product Structure
The 180-minute fire-resistant aluminum alloy busway product consists of four core components: high-purity aluminum alloy conductor bars, a high-performance fire-resistant insulation system, fire-resistant support brackets, and a high-strength steel outer casing.
Conductor: high-purity electrical-grade aluminum alloy bars (aluminum content ≥99.5%) are used as the conducting material, with a resistivity below 0.0283 Ω·mm²/m. The surface of the aluminum alloy bars is tin-plated, which effectively enhances oxidation and corrosion resistance, lowers contact resistance, and improves connection reliability. Aluminum has a density of 2.7 g/cm³, about one-third that of copper, so a busbar of the same length is substantially lighter. The cross-section and length of the aluminum bars are designed to the specific load requirements; their conductivity is about 60%–65% that of pure copper, and by properly increasing the cross-section, a current-carrying capacity close to that of copper bars can be achieved. The aluminum bar specifications cover the full range of current ratings from 250A to 5000A, allowing flexible configuration for different load requirements.
Insulation system: the surface of the aluminum bars is wrapped in multiple layers of fire-resistant mica tape. The mica tape complies with the JB/T5019.20-85 "Electrical Insulating Mica Products" and JB/T6488-1~3-92 "Mica Tape" standards, and under normal conditions has good flexibility along with high heat resistance and good dielectric and mechanical properties. The mica tape retains very high insulation performance at temperatures up to 950°C, and still maintains very high insulation performance at 600°C. The insulation layer uses ceramifiable silicone rubber or mica tape, which can carbonize under high heat to form a ceramic-like protective layer — a significant safety improvement compared with ordinary busway (PVC insulation, rated for only 70°C)
. To meet fire-resistance-rating requirements, the aluminum bar surface is wrapped with multiple layers of synthetic mica tape (typically 10 to 15 layers), wound evenly and tightly to form a multi-layer composite insulation structure that ensures the insulation performance does not fail at high temperatures.
Brackets: the brackets are made of fire-resistant insulating material and feature multiple grooves into which the busbars are seated and secured. High-temperature alumina ceramic parts are used for insulating support and can withstand temperatures up to 1000°C-
. Both the phase-separator blocks and the joint insulation plates are made of ceramic Al₂O₃ material, which offers excellent high-temperature resistance and anti-aging performance.
Casing: made of high-strength steel with a profile thickness of no less than 2mm and an anodized surface finish. The casing uses a combined structure of two side plates plus top and bottom covers; the side plates feature heat-dissipation fins and dovetail grooves, and are assembled screw-free via a hook-and-groove connection, giving a high protection rating. After the casing surface undergoes rust removal, degreasing, and phosphating/drying, it is sprayed with a fire-resistant coating; within 3 to 5 minutes of a fire starting, the coating begins to foam and expand, forming a dense carbonized insulating layer that seals every gap in the busway casing. This effectively reduces heat transfer and closes off all openings, preventing fire-fighting water from entering and causing a busbar short circuit, so normal power supply is maintained
. The side plates on both sides of the casing use a double-layer hollow structure; this tight hollow design effectively blocks high-temperature gas or open flame from entering the interior of the busway-
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The product uses a well-engineered sandwich-style tightly-laminated phase conductor structure, giving the busway a compact, small-footprint form; the busbar system has low impedance, low voltage drop, and good dynamic-thermal stability as its main advantages-
. Joints use dedicated fire-resistant insulating components for reliable, convenient connection. A non-magnetic aluminum alloy casing with good conductivity is used as the protective earth conductor, surrounding the conductor bars on all sides; because it sits as close as possible to the three-phase busbars, it achieves minimal reactance, and since the protective earth conductor is equidistant from all three phase busbars, its reactance is identical for each-
. This integrated grounding technique performs better than a separate PE bar, and is consistent with the technical direction advocated by the electrical technical committee of using the busway casing itself as the grounding conductor.
III. Core Performance Characteristics
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Ultra-high fire resistance. The product has passed testing under the GA/T 537-2005 standard, maintaining circuit integrity for more than 180 minutes in flame at 950°C to 1000°C. Fire resistance time is the core metric for fire-resistant busway, and the national standard requires a sustained fire-resistance capability of ≥180 minutes-
. This product meets the 950°C, 180-minute fire-resistance requirement and can be used in settings with high fire-safety requirements-
. For the evacuation lighting and smoke-control system supply trunks of civil buildings taller than 100m, fire-resistant busway rated at 950°C for 180 minutes or higher should be used. Jiuwei currently classifies fire-resistant busway on the market into five grades: 180-minute fire resistance, 120-minute fire resistance, 45-minute fire resistance, 5-minute fire resistance, and fire-retardant but not fire-resistant; this 180-minute fire-resistant product is the highest fire-resistance grade-
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Lightweight design, easy installation. Aluminum has a density of only 2.7 g/cm³, about one-third that of copper, so a busway of the same length is substantially lighter. Compared with copper-bar fire-resistant busway, aluminum-bar fire-resistant busway is roughly two-thirds lighter, making transportation and installation more convenient and significantly cutting construction cost and installation difficulty. In space-constrained scenarios requiring vertical installation or hoisting — such as electrical shafts in high-rise buildings or metro tunnels — the lightweight advantage of aluminum-conductor fire-resistant busway is especially pronounced, substantially reducing installation labor intensity and shortening the construction schedule.
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Excellent electrical insulation performance. Under normal conditions, insulation resistance reaches 20 MΩ or above (per GB standard requirements)-
. The busbar system can withstand a 3750V power-frequency withstand voltage test for 1 minute with no breakdown or flashover. When operating continuously at rated current, temperature rise does not exceed: 60K at connection terminals, 30K at the metal casing, and 40K at the surface of the in-trunk insulating components-
. After a fire breaks out, the busway system continues to operate normally even as the combustion temperature rises to 960°C-
. The insulation layer uses mica tape, which can carbonize under high heat to form a ceramic-like protective layer, significantly improving safety compared with ordinary busway. -
Double-layer casing structure, high protection rating. The casing uses a double-layer hollow structure made of aluminum-magnesium alloy profile, effectively blocking high-temperature gas or open flame from entering the busway. The casing surface is anodized and then sprayed with fire-resistant coating; when exposed to fire, the coating rapidly expands to form a dense carbonized insulating layer that seals every gap in the busway casing, preventing high heat from reaching the interior. The protection rating reaches IP54 to IP67, allowing it to withstand fire-sprinkler spray and ensuring the integrity of the power supply line under fire conditions.
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Excellent mechanical performance and corrosion resistance. The product casing is made of high-strength aluminum-magnesium alloy, giving it high structural strength and load-bearing capacity. After anodizing, the aluminum alloy casing has excellent corrosion resistance and has passed salt-spray testing, allowing long-term use in harsh environments with high salt spray and high humidity. The product's seismic performance meets the relevant standard requirements, ensuring safe power supply under extreme conditions such as earthquakes.
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Good dynamic-thermal stability. Its sandwich-style tightly-laminated phase conductor structure gives the busbar system low impedance and low voltage drop, along with good dynamic-thermal stability. The aluminum conductor bars are arranged closely together and fit tightly against the side plates, effectively reducing temperature rise.
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Full range of specifications, flexible configuration. The product's current ratings cover 250A, 400A, 630A, 800A, 1000A, 1250A, 1600A, 2000A, 2500A, 3150A, 4000A, and 5000A, and it can be flexibly configured as a three-wire, four-wire, or five-wire system. Standard section lengths are set according to the current rating, for convenient on-site installation and transport.
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Integrated grounding technology, superior protective performance. A non-magnetic aluminum alloy casing with good conductivity serves as the protective earth conductor, surrounding the conductor bars on all sides. This integrated grounding technique keeps the protective earth conductor as close as possible to the three-phase busbars, achieving minimal reactance, with the protective earth conductor equidistant from — and thus having identical reactance to — all three phase busbars-
. Whether the fault is a brief or a sustained phase-to-ground short circuit, this grounding method performs better than a separate PE bar. -
Significant cost advantage, outstanding value for money. Aluminum typically costs only one-quarter to one-third as much as copper, so raw material cost is substantially lower than for copper-bar fire-resistant busway products. Against a backdrop of persistently high copper prices, the cost advantage of aluminum-bar fire-resistant busway is especially clear, effectively controlling procurement cost early in a project. Jiuwei's alloy fire-resistant busway is an option that maintains electrical performance while significantly lowering cost-
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Safe and environmentally friendly. The product complies with the RoHS/REACH standards; its main materials do not produce toxic or hazardous gases in a fire, making it safe and environmentally friendly. The insulating material is halogen-free and does not release toxic gases at high temperature, helping ensure the safety of evacuating personnel.
IV. Core Manufacturing Process Features
The 180-minute fire-resistant aluminum alloy busway product employs a range of advanced technologies and strict control measures in its manufacturing process to ensure precision, reliability, and consistency.
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Automated processing technology. Jiuwei Busway uses automated stamping, bending, and welding equipment combined with precision measurement systems to keep machining accuracy within ±0.5mm. The cutting, punching, and bending of aluminum alloy sheet metal are tightly controlled to ensure precise casing dimensions and a sturdy structure. Some production lines have already introduced an MES system, enabling full-process traceability from raw material receipt through to finished-product shipment.
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Aluminum alloy conductor pretreatment process. The surface of the aluminum bars undergoes pickling, phosphating, and anti-oxidation treatment, effectively removing the surface oxide layer and enhancing conductive contact performance. The aluminum bar surface is then tin-plated to further improve oxidation resistance and reduce contact resistance, ensuring reliable contact over long-term operation. The cutting, punching, and surface-treatment processes for the aluminum bars are tightly controlled to ensure precise conductor dimensions and a smooth, burr-free surface.
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Multi-layer mica tape winding process. The aluminum bar surface is wrapped with multiple layers of synthetic mica tape (typically 10 to 15 layers), wound evenly and tightly to ensure the insulation layer is free of bubbles and wrinkles. Automated equipment controls the winding tension and layer count during the process, keeping the insulation layer quality consistent across every aluminum bar. After winding, each aluminum bar undergoes withstand-voltage testing and insulation-resistance testing to ensure its insulation performance meets requirements.
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Screw-free assembly process. The top and bottom covers of the aluminum alloy casing connect to the side plates via a hook-and-groove structure, requiring no screws, rivets, or welding. Because no holes are made in the casing, moisture and dust cannot get in, which raises the protection rating and gives it a very clean appearance. The side plates are designed with heat-dissipation fins and dovetail grooves, which aid busway heat dissipation, strengthen the casing, make installation more convenient, and reduce the overall weight of the busway.
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Fire-resistant coating spraying process. After the casing surface undergoes rust removal, degreasing, and phosphating/drying, an electrostatic spraying process is used to evenly apply fire-resistant powder or coating. The spray thickness is precisely controlled to ensure that, in the event of a fire, the coating can quickly foam and expand to form a dense carbonized insulating layer. All performance indicators of the fire-resistant coating comply with the GB14907-94 standard.
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Double-layer hollow casing forming process. The side plates on both sides of the casing use a proprietary double-layer hollow structure formed through precision roll forming. This tight double-layer hollow structure effectively blocks high-temperature gas or open flame from entering the interior of the busway, while also strengthening the mechanical strength of the casing.
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Precision ceramic bracket machining process. The insulating support components are high-temperature alumina ceramic parts, machined via a precision molding process for accurate dimensions and a smooth surface. The ceramic brackets offer excellent heat resistance up to 1000°C, maintaining structural integrity and insulation performance in a flame environment.
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Modular design and factory prefabrication. Before leaving the factory, the product is already fabricated into the appropriate straight sections, elbow sections, T-tap sections, feeder heads, and so on, per the specific project layout requirements, making on-site installation convenient. All components are prefabricated, so on-site work requires only simple connections — installation is straightforward and maintenance is easy.
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Comprehensive quality inspection system. Quality inspection covers electrical performance testing (such as withstand-voltage and insulation-resistance measurement), mechanical strength testing, and fire-resistance performance verification. The product has passed CCC type testing and fire-resistance performance verification under GA/T 537-2005
. A contact-resistance tester is used to control joint contact resistance, ensuring the joint temperature rise meets standard requirements.
V. Diverse Application Scenarios
Thanks to its lightweight design, significant cost advantage, ultra-high fire resistance, excellent electrical insulation performance, and reliable structural design, the 180-minute fire-resistant aluminum alloy busway product is widely used in a range of important locations with strict requirements for fire-protection power supply safety and continuity.
(1) Super-Tall Buildings and High-Rise Civil Buildings
The fire protection systems of super-tall buildings and high-rise civil buildings demand extremely high power supply reliability. For civil buildings taller than 100m, the supply trunks of the evacuation lighting and smoke-control systems should use fire-resistant busway rated at 950°C for 180 minutes or higher. The supply trunks for fire control rooms, fire lifts, and fire pumps likewise require power lines with a high fire-resistance grade. Fire-resistant busway should be used to supply a high-rise building's vertical fire-protection distribution trunk when the calculated current is 400A or above. The product is installed vertically in the electrical shafts of high-rise buildings as the main supply line for fire-protection loads, ensuring that critical equipment — fire pumps, sprinkler systems, smoke-exhaust fans, emergency lighting, fire lifts, and the like — can keep running for more than 180 minutes when a fire breaks out, buying valuable time for evacuation and fire rescue. The lightweight advantage of the aluminum alloy conductor is especially notable in vertical installations in high-rise buildings, substantially reducing the structural load burden and installation difficulty.
(2) Large Commercial Complexes and Public Venues
Large shopping malls, commercial plazas, hotels, and other crowded venues have extremely strict fire-safety requirements. The 180-minute fire-resistant aluminum alloy busway product provides reliable power for the fire-protection systems of these venues. Equipment such as fire shutter doors, smoke-control systems, emergency lighting, and fire broadcast systems within a mall require highly reliable supply trunks. The compact structure of fire-resistant busway can be concealed within the building structure without affecting the overall look of the commercial space, and its modular design makes it easy to flexibly adjust the distribution scheme to fit the commercial layout. In large, crowded public venues, the safe and environmentally friendly nature of fire-resistant busway is especially important — the high heat of a fire does not release toxic gases, keeping evacuation routes safe for occupants.
(3) Metro and Rail Transit
Metro stations are public venues with extremely high foot traffic, and once a fire breaks out, the reliability of the power supply system is directly tied to passenger safety. Equipment in a metro station — signaling systems, ventilation systems, platform screen doors, emergency lighting, escalators, and the like — needs highly reliable power. The 180-minute fire-resistant aluminum alloy busway product can keep supplying power in a fire environment inside metro tunnels and stations, ensuring the normal operation of emergency equipment and evacuation systems. The product is widely used in high-traffic public venues such as metro systems and other locations with high fire-protection requirements. Its double-layer casing structure and fire-resistant insulating-layer design effectively resist the high heat and smoke exposure found in a tunnel environment. The lightweight nature of the aluminum alloy conductor makes installation and maintenance easier within the confined space of a tunnel, and it is widely used in rail transit traction substations and station distribution systems.
(4) Airport Terminals and Transportation Hubs
Airport terminals are massive public buildings with dense crowds and a great deal of equipment, placing extremely high demands on the fire-protection power supply system. Equipment throughout a terminal — security screening, baggage handling systems, information centers, emergency lighting, HVAC systems, fire pumps, and so on — all require a reliable fire-protection power supply. With its 180-minute fire-resistance limit, the 180-minute fire-resistant aluminum alloy busway product can keep critical equipment powered when a fire occurs, ensuring an orderly evacuation of terminal occupants and smooth fire rescue operations. The lightweight advantage of the aluminum alloy conductor can significantly reduce construction difficulty and safety risk during high-elevation installation work in long-span buildings.
(5) Hospitals and Medical Facilities
Large general hospitals demand extremely high stability and safety from their electrical systems — in critical areas such as operating rooms, ICUs, and imaging departments in particular, a power interruption would directly endanger patients' lives. A hospital's fire-protection distribution system needs to meet the power-supply requirements of a first-class load. The 180-minute fire-resistant aluminum alloy busway product provides highly reliable power for a hospital's fire pumps, smoke-control systems, emergency lighting, and backup power for medical equipment. The high fire resistance and low smoke toxicity of fire-resistant busway ensure it does not cause secondary harm to patients and medical staff in the event of a fire.
(6) Data Centers and Information Infrastructure
Data centers demand extremely high stability and reliability from their electrical systems, and with dense, high-value equipment, fire risk prevention and control is especially important. Systems throughout a data center — fire protection, emergency lighting, cooling, security, and so on — need highly reliable power. The 180-minute fire-resistant aluminum alloy busway product gives a data center's fire-protection loads up to 180 minutes of continuous power supply capability, ensuring the fire-protection system can keep operating in the event of a fire and protecting data assets to the greatest extent possible. The product's compact structure makes flexible cabling and installation easier within a data center facility, and the lightweight aluminum alloy conductor design makes flexible cabling and maintenance easier as well.
(7) Sports Venues and Large Public Facilities
Sports venues need high-power supply for their fire-protection systems, emergency lighting, broadcast systems, and more. During major sporting events, occupant density is extremely high, making fire safety especially important. The 180-minute fire-resistant aluminum alloy busway product can provide stable, reliable power to a sports venue's fire-protection equipment, ensuring that critical equipment — fire pumps, smoke-control systems, emergency lighting, and so on — keeps running in an emergency. Its modular design allows for fast installation, suited to the tight construction schedules typical of sports venue projects.
(8) Critical Control Centers and Emergency Command Centers
Important control locations — fire control rooms, emergency command centers, integrated urban management platforms, and the like — demand extremely high power-supply reliability. These locations must keep operating during emergencies such as fires, providing command support for fire rescue and emergency management. The 180-minute fire-resistant aluminum alloy busway product provides a highly reliable supply line for the fire-protection loads of these important locations, ensuring the normal operation of a control center's critical equipment — communication systems, monitoring systems, dispatch systems, and so on — when a fire occurs.
(9) Industrial Plants and Petrochemical Enterprises
Large industrial plants, petrochemical enterprises, and similar sites hold large quantities of flammable and explosive materials, creating high fire risk. The fire-protection systems at these sites require highly reliable power. Thanks to its excellent fire resistance and impact resistance, the 180-minute fire-resistant aluminum alloy busway product can keep equipment — fire pumps, foam fire-suppression systems, emergency lighting, and so on — powered in a fire environment. The cost advantage of the aluminum alloy conductor is especially notable across the large-scale fire-protection distribution networks found in industries such as chemical processing, effectively reducing project investment cost.
(10) Connections from Diesel Generators to Distribution Cabinets
Per the requirements of the GA/T 537-2005 standard, fire-resistant busway can be applied to fire-protection emergency power lines such as those from diesel generator to distribution cabinet, or from distribution cabinet to sub-distribution cabinet. When a fire breaks out and the diesel generator set starts up as the emergency power source, fire-resistant busway ensures the power output from that emergency source can be safely transmitted to each fire-protection load terminal, keeping fire-protection equipment running continuously.