WDZBN-YJY73 Class B Enhanced Low Smoke Zero Halogen Steel Tape Armored XLPE Power Cable for Direct Buried, Pipe Gallery & Anti-Mechanical Damage Public Engineering

Professional code interpretation tailored for electrical engineering teams

• WDZ: Low Smoke Zero Halogen (LSZH); utilizes halogen-free insulation and sheath materials that do not emit toxic or corrosive gases when exposed to open flames.
• B: Class B flame-retardant rating; meets moderate fire safety standards for public and civil buildings.
• N: Enhanced bundled flame-retardant formulation; effectively inhibits vertical flame propagation when multiple cables are laid in close proximity.
• YJ: XLPE (Cross-linked Polyethylene) insulated core; features high heat resistance and extremely low dielectric loss.
• Y: Inner Low Smoke Zero Halogen polyolefin sheath (LSZH inner sheath).
• 73: Double steel tape armor + outer LSZH polyolefin sheath; the steel tape layer provides superior mechanical protection, effectively resisting crushing forces, puncture by sharp debris, and external impacts.

WDZBN-YJY73 is an armored upgrade of the standard WDZBN-YJY cable. By adding a double steel tape mechanical reinforcement layer to the Class B enhanced LSZH flame-retardant cable, it overcomes the inherent weaknesses of unarmored LSZH cables—specifically their limited resistance to underground crushing, puncture by sharp debris, and impact damage from construction machinery. Designed for various fixed installation projects, it is suitable for direct burial, utility tunnels, tunnel wall mounting, outdoor cable trenches, and impact-resistant cable tray installations in basements, perfectly balancing moderate fire safety, eco-friendly halogen-free performance, and robust mechanical protection.

• Class 2 compacted stranded oxygen-free copper conductor: Circular compacted stranding offering low DC resistance and stable performance for long-distance, high-current transmission.
• Irradiation-crosslinked XLPE insulation: Uniform extruded wall thickness, capable of withstanding 90°C long-term heat, with excellent aging resistance and water-treeing inhibition.
• Halogen-free, low-smoke, flexible filler: Provides circular shaping and eliminates internal air gaps, reducing heat accumulation during dense parallel installation.
• Polyester tape separator: Fully wraps the cable core to prevent frictional wear on the insulation layer during pulling and installation.
• LSZH (Low-Smoke Zero-Halogen) inner sheath: Isolates the cable core from the steel tape armor, preventing chemical corrosion of the insulation by the metal layer.
• Double-layer galvanized steel tape armor: Overlapping double-layer steel tape structure forming a robust mechanical protective barrier against underground rocks, vehicle crushing, and construction impacts.
• WDZBN modified flame-retardant LSZH outer sheath: UV-resistant, moisture-proof, low-smoke, and halogen-free outer protection; encapsulates the steel tape armor to prevent rust and environmental corrosion.

Domestic mandatory standards: GB/T 12706.2 (Standard for armored power cables), GB/T 19666 (General requirements for low-smoke, halogen-free cables), GB 31247 (Classification of combustion performance and combustion test standards for low-smoke, halogen-free cables), GB 50016 (Code for fire protection design of buildings), GB 50217 (Code for design of electric power engineering cables)

Concurrently applied international testing standards: IEC 60228 (Conductor specifications), IEC 60332-3B (Flame retardancy test for bunched cables), IEC 61034 (Smoke density test), IEC 60754 (Halogen emission test), IEC 60502 (Mechanical strength test for armored cables)

Mainstream general-purpose low-voltage rating: 0.6/1 kV (covering over 99% of direct-buried power distribution projects for public buildings)

Customized medium/low-voltage option: 1.8/3 kV, specifically for auxiliary power circuits in long-distance underground utility tunnels

Single-core WDZBN-YJY73: 10 mm² – 630 mm² (armored direct-buried installations rarely involve small cross-sections below 10 mm²)

Multi-core WDZBN-YJY73: 2/3/4/5 cores, as well as composite core configurations such as 3+1, 3+2, and 4+1; cross-section range: 10 mm² – 400 mm²

Conductor material specifications: 99.99% virgin T2 oxygen-free copper; manufactured using a compact stranding process to minimize internal voids, thereby enhancing actual current-carrying capacity under the heat dissipation constraints typical of direct-buried installations

• Long-term continuous operating temperature: 90°C; current-carrying capacity exceeds that of traditional PVC-insulated armored VV22 cables.
• Short-circuit withstand temperature: Withstands instantaneous temperatures of 250°C for 5 seconds without insulation melting or dielectric breakdown.
• Class B Enhanced bunched flame-retardant performance: Passes the IEC 60332-3B vertical bunched cable combustion test; flames do not propagate vertically along bunched armored cables.
• Low-smoke Class B standard: Smoke light transmittance ≥60%; maintains visibility sufficient for basic evacuation during fire emergencies.
• Halogen-free performance: Total halogen emission <0.5%; produces no corrosive hydrogen chloride gas, preventing harm to personnel and firefighting equipment.
• Double steel-tape armor mechanical performance: Withstands 2000N of crushing force and 1000N of external impact; resists puncture by sharp debris during direct-burial installation.
• Minimum installation bending radius: 15 times the outer diameter for multi-core armored cables; 20 times the outer diameter for large-cross-section single-core armored cables (values ​​are higher than those of unarmored YJY series due to the steel tape layer).
• Installation ambient temperature range: -20°C to +70°C; allows for standard direct-burial installation without preheating in low-temperature winter conditions.
• Factory withstand voltage test: All finished armored cables pass a 3.5kV AC withstand voltage test (duration: 5 minutes) prior to delivery, with no insulation breakdown.
• Steel tape corrosion resistance: Utilizes hot-dip galvanized steel tape; resists long-term corrosion in moist soil environments without rusting through.

• Small-to-medium cross-sections (10 mm² – 95 mm²): Underground lighting for residential complex garages, underground branch power distribution for campuses, and wiring for ventilation systems in underground pedestrian walkways.
• Medium cross-sections (120 mm² – 185 mm²): Underground incoming main power lines for office buildings and underground fire-safety circuits for community commercial center basements.
• Large cross-sections (240 mm² – 630 mm²): Main power supply cables for municipal utility tunnels and underground main distribution feeders for new school campuses.

1. Double-layer steel tape armor provides industry-leading resistance to mechanical damage. The double-layer overlapping galvanized steel tape reinforcement distinguishes this cable from unarmored WDZBN-YJY cables. In direct-burial applications lacking rigid steel conduit protection, this structure effectively withstands damage caused by the crushing force of sharp rocks, heavy surface loads, and accidental impacts from construction machinery. For complex municipal tunnel and utility corridor projects, this armor layer significantly reduces the frequency of post-installation maintenance and repairs, thereby resolving the primary risk associated with using unarmored Low-Smoke Zero-Halogen (LSZH) cables in underground applications.
2. Dual-layer LSZH (Low-Smoke Zero-Halogen) sheathing protects the steel tape from underground corrosion The steel tape armor is fully encapsulated between an independent inner LSZH separation sheath and an outer flame-retardant LSZH protective sheath. The inner sheath prevents the metal steel tape from scratching the XLPE-insulated cores during cable bending and pulling operations, while the outer LSZH sheath acts as a barrier against underground soil moisture and mildly acidic or alkaline substances. This prevents corrosion and perforation of the galvanized steel tape during long-term underground service, thereby extending the cable's overall service life to 70 years—matching the design lifespan of public buildings.
3. Enhanced Class B flame retardancy and halogen-free fire safety characteristics It retains all the fire safety advantages of the base WDZBN-YJY model: the enhanced Class N flame-retardant formulation effectively inhibits flame propagation when multiple armored cables are stacked on supports within enclosed utility tunnels; the halogen-free formulation eliminates secondary hazards caused by toxic smoke in confined underground spaces such as tunnels and utility galleries, fully complying with fire safety acceptance standards for schools, commercial facilities associated with residential complexes, and municipal underground utility projects.
4. XLPE insulation enhances current-carrying capacity for directly buried cables with limited heat dissipation Directly buried cables face poorer heat dissipation conditions compared to cables installed in indoor air-filled shafts. The WDZBN-YJY73 cable utilizes XLPE insulation rated for 90°C; for a given conductor cross-section, its steady-state current-carrying capacity is 16%–24% higher than that of the PVC-insulated, armored VV22 cable (rated for 70°C). When planning long-distance, directly buried trunk lines, engineers can avoid the unnecessary selection of larger conductor cross-sections solely to meet capacity requirements, thereby striking a balance between the risks associated with heat accumulation in direct burial and overall material procurement costs.
5. Broad environmental adaptability reduces investment in auxiliary conduit infrastructure Featuring a Low-Smoke Zero-Halogen (LSZH) outer sheath, this cable offers resistance to UV radiation, moisture, and mild chemical corrosion. Complemented by steel-tape armor, it can be directly buried in standard soil or installed in outdoor cable trenches, semi-underground equipment rooms, and on tunnel-wall brackets without the need for heavy-duty anti-corrosive steel conduits. For large-scale direct-burial power distribution projects in industrial parks or residential communities, this solution significantly lowers the costs associated with procuring and installing protective conduits.
6. A stable, integrated armoring production process ensures consistency in mechanical and fire-resistance performance across batches. The fully automated production line—featuring armoring tape wrapping and co-extrusion of dual-layer Low-Smoke Zero-Halogen (LSZH) materials—strictly standardizes parameters such as the steel tape overlap ratio, flame-retardant plastic formulation, and XLPE insulation specifications. This process rigorously controls variations in mechanical impact strength, smoke density, and flame-retardant performance between production batches, thereby eliminating the risk of failing project fire safety inspections or mechanical performance spot checks due to inconsistent batch quality.

• Underground power distribution for mid-to-high-rise commercial and office buildings Outdoor underground main feeder lines; direct burial of fire pump control cables in basements; impact-resistant cable tray routing in underground equipment rooms
• Underground public power lines for educational campuses Underground main feeder lines for primary/secondary schools and universities; underground power supply for student dormitories; underground distribution cables for sports field lighting
• Underground facilities supporting residential areas Underground lighting for community garages; underground installation of shared fire safety lines; power routing for emergency evacuation systems in underground pedestrian passages
• Municipal underground infrastructure projects Auxiliary power cables for urban utility tunnels; underground main feeder lines for ventilation and fire safety systems in urban road tunnels; underground power distribution lines for municipal parks
• Outdoor underground layouts for general public service buildings Outdoor underground power supply for regional cultural centers and community health service stations; impact-resistant cable routing in public gymnasium basements

1. Case Study 1: Electrical Installation for the New Campus of a Key Secondary School The project's electrical design specifications mandated the use of WDZBN-YJY73 steel-tape armored cables for all outdoor buried power distribution trunk lines. Unarmored WDZBN-YJY cables were rejected because the rocky soil at the construction site posed a high risk of puncturing the cable sheath during direct-burial installation; meanwhile, PVC-sheathed VV22 armored cables failed to meet fire safety regulations regarding "low-smoke, zero-halogen" (LSZH) standards. Our company provided comprehensive mechanical strength test reports for the armor and certification documents confirming the cable's Class B enhanced flame-retardant and LSZH properties. This documentation enabled the project to pass fire safety inspections and construction quality acceptance tests on the first attempt, with no remedial work required. The double-steel-tape armor structure effectively prevented cable damage during the extensive earth backfilling operations, and no insulation breakdown failures occurred after a full year of operation at maximum load.
2. Case Study 2: Retrofit Project for the Underground and Outdoor Buried Cabling of an 18-Story Community Commercial Complex The general contractor's procurement team selected the WDZBN-YJY73 series of armored cables for the underground fire pump circuits and the outdoor buried main power lines supplying the retail units. The cable’s dual-layer Low-Smoke Zero-Halogen (LSZH) sheath effectively withstands the perpetually damp underground soil environment, while the galvanized steel tape armor layer withstands the crushing forces exerted by vehicles driving over the underground passageways. We provided customized, cut-to-length services based on the underground utility layout drawings; compared to bulk purchasing in uniform lengths, this reduced cable offcut waste by 13%, thereby optimizing the electrical material budget for the entire retrofit project.
3. Case Study 3: Power Infrastructure Project for Phase I of the Urban East District Utility Tunnel Municipal tender requirements mandated that cables fixed to the utility tunnel walls must be armored, LSZH-rated cables capable of withstanding mechanical crushing forces. Design engineers ultimately designated the WDZBN-YJY73 as the sole compliant model. Our technical team assisted the procurement department in compiling CCC certification, mechanical performance test reports for the armor, and IEC test data regarding LSZH and flame-retardant properties. This documentation fully satisfied the detailed comparative criteria outlined in the government tender, significantly boosting the general contractor's overall evaluation score. Upon project completion, third-party on-site sampling and testing—including impact and crush resistance tests—confirmed that all mechanical performance and fire safety metrics successfully met acceptance standards.

• Voltage Rating Selection Rules: Standard 0.6/1kV WDZBN-YJY73 cables are to be used for direct-burial installation in conventional public buildings; custom-specified 1.8/3kV armored cables may be selected for long-distance municipal utility tunnel trunk lines.
• Cross-Section Calculation Logic: Due to poor heat dissipation conditions associated with direct-burial installation, load current calculations must be based on the total equipment power, incorporating a load expansion margin of 18%–20%; cable selection should leverage the high current-carrying capacity of XLPE (cross-linked polyethylene) to avoid material cost waste caused by indiscriminately increasing the cross-sectional area.
• Core Count Matching Criteria: 3-core WDZBN-YJY73 cables are selected for single-phase direct-buried lighting branch circuits; 4-core cables are used for three-phase fire-fighting equipment direct-buried trunk lines; 3+1 or 4+1 composite-core cables are selected for public equipment requiring grounding protection.
• Application-Specific Guidance: WDZBN-YJY73 is the optimal choice for direct-burial, tunnel, and impact-resistant basement projects requiring a medium fire-safety rating; for critical direct-buried evacuation circuits in super-high-rise buildings, subways, and large hospitals, an upgrade to Class A low-smoke armored cables (WDZA-YJY73) is required; for underground installation in highly corrosive chemical plants, armored cables must be enclosed within fully sealed, heavy-duty anti-corrosion steel conduits.

• Direct-burial specifications: A 10 cm thick fine sand bedding layer must be laid both beneath and above the cable, followed by a protective layer of solid bricks to shield it from large, sharp stones; for sections subject to frequent heavy vehicle traffic, an additional HDPE protective conduit should be installed over the armored cable to provide secondary protection.
• Strict control of bending: Installation must comply with minimum bending radius standards (15 times the outer diameter for multi-core cables and 20 times for single-core cables); excessive bending can cause deformation of the double steel-tape armor, cracking of the internal Low-Smoke Zero-Halogen (LSZH) sheath, and damage to the insulated cores.
• Installation in utility tunnels and galleries: Cable support brackets must be installed at 2-meter intervals; a 30% heat dissipation gap must be maintained between parallel, stacked armored cables to prevent heat accumulation from reducing the actual current-carrying capacity.
• Low-temperature winter installation: The LSZH outer sheath of the WDZBN-YJY73 cable retains good toughness at -20°C, requiring no pre-heating prior to pulling or bending, making it suitable for municipal direct-burial projects in northern regions.

• Pre-order Qualification Verification: Confirm that the supplier can provide the CCC mandatory certification, the mechanical strength test report for double-layer steel tape armoring, and the inspection certificate for Class B flame-retardant, low-smoke zero-halogen (LSZH) properties.
• Goods Acceptance and Spot Checks: Verify the clear laser-printed markings on the outer sheath (e.g., "WDZBN-YJY73 0.6/1kV + cross-sectional specification"); inspect the uniformity of the steel tape overlap, the compactness of the copper core, and the consistency of the double-layer LSZH sheath thickness. For municipal, school, and government tender projects, samples must be taken for third-party spot checks regarding mechanical impact resistance and fire safety performance.
• Advance Planning of Delivery Schedules: For bulk orders destined for large campuses, municipal utility tunnels, or underground community installations, orders should be placed 12 to 18 working days in advance. This lead time accounts for raw material production, the armoring/wrapping process, and finished product sampling/testing, thereby preventing construction stoppages caused by cable supply shortages.

• Meets domestic standards: The full series of WDZBN-YJY73 armored cables fully complies with the GB/T 12706.2 standard for armored cables and the GB 31247 mandatory specification for Low-Smoke Zero-Halogen (LSZH) fire safety; all performance indicators meet the acceptance criteria set by engineering quality supervision stations and fire rescue bureaus.
• Qualified for international-standard testing: Passes the full suite of IEC tests for armored mechanical performance and LSZH fire safety; official test reports are available for submission during the bidding process for overseas municipal underground projects.
• One-stop provision of complete batch documentation: CCC certification, mechanical performance test reports for double steel-tape armor, Class B flame-retardant LSZH test reports, factory batch inspection reports, certificates for T2 copper and LSZH flame-retardant plastic raw materials, technical parameter compliance tables for bidding, and special VAT invoices.
• Guaranteed batch quality consistency: Each production batch utilizes standardized galvanized steel tape specifications, a unified LSZH flame-retardant formula, and an automated armor-wrapping process. This ensures minimal batch-to-batch variation in mechanical durability and fire safety performance, eliminating the risk of project acceptance failure caused by non-compliant armored cables in specific batches.

Our product range is extensive, covering everything from small-gauge (10mm²) armored branch cables for direct burial to large-cross-section (630mm²) armored trunk cables for utility tunnels. We maintain ample stock of common models used in schools, residential communities, and municipal direct-burial projects to ensure rapid delivery. We offer services such as custom-length cutting, laser printing of project-specific identifiers on the outer sheath, and an upgrade option featuring "double-layer fire-resistant mica tape" for dedicated fire-safety direct-burial circuits. This enables one-stop, centralized procurement of premium Low-Smoke Zero-Halogen (LSZH) armored cables, eliminating the hassle of coordinating with multiple suppliers.

We exclusively utilize high-quality imported low-smoke, zero-halogen (LSZH) flame-retardant masterbatch, prime-grade T2 virgin oxygen-free copper, and standard hot-dip galvanized anti-corrosion steel tape; we strictly reject inferior recycled halogen-free plastics and thin, ungalvanized steel tapes that fail to meet mechanical performance standards. We implement a comprehensive five-tier inspection process: halogen and mechanical property testing of incoming raw materials; in-line monitoring of copper conductor stranding; automatic thickness detection during XLPE insulation extrusion; real-time control of steel tape armor wrapping; and batch-based impact resistance and flame-retardancy sampling of finished armored cables. This approach effectively eliminates quality defects common among smaller manufacturers—such as steel tape that is too thin and prone to corrosion, inadequate flame-retardant performance, and uneven thickness in LSZH sheathing.

By bypassing wholesale markups from intermediaries, we offer tiered volume discounts for bulk orders of armored cables destined for large-scale campuses and municipal utility tunnels. Our team of senior electrical engineers provides complimentary services—including calculations for direct-burial current-carrying capacity, optimization of conductor cross-section selection, and design recommendations for installation (covering sand bedding and protective measures). We assist purchasers in selecting the most cost-effective WDZBN-YJY73 armored cable specifications while fully meeting mechanical durability and fire safety standards, thereby lowering the total investment in electrical materials for underground direct-burial projects.

Our team, comprised of electrical engineers with over 15 years of experience in municipal underground cable design, offers comprehensive technical support to design institutes and general contractors. Services include consulting on power distribution circuit design for direct-burial applications in public buildings, provision of downloadable WDZBN-YJY73 current-carrying capacity reference tables, compilation of data regarding mechanical and fire safety parameters for tender submissions, and guidance on preparing documentation for fire safety inspections. For government, educational, and utility tunnel tenders, we assist in creating comparative tables for mechanical strength and Low-Smoke Zero-Halogen (LSZH) fire safety metrics that comply with stringent tender requirements, significantly enhancing the contractor's competitiveness in winning the bid.

Equipped with multiple XLPE continuous co-extrusion and automatic steel-tape armoring lines, the facility achieves high daily output for WDZBN-YJY73 cables, supported by extensive on-site storage for copper, galvanized steel tape, and LSZH (Low-Smoke Zero-Halogen) materials. Even for massive orders—such as those for new campus developments or municipal utility tunnel installations—delivery is guaranteed within the established schedule, thereby eliminating the risk of civil construction delays caused by supply shortages of armored cables.

All delivered WDZBN-YJY73 steel-tape armored cables come with a 15-year manufacturer’s quality warranty covering key performance indicators, including mechanical armoring integrity and LSZH fire safety. A professional technical team provides remote video guidance within 24 hours to resolve technical challenges encountered during underground installation. Additionally, free training on underground armored cable installation is available for long-term municipal engineering partners and school construction contractors. Dedicated profiles are maintained for high-volume clients, allowing for the advance stockpiling of raw materials aligned with project schedules, thereby shortening lead times for subsequent reorders.

The WDZBN-YJY73 is a Class B enhanced, low-smoke zero-halogen (LSZH), double-steel-tape armored XLPE power cable. It serves as a specialized cabling solution for applications requiring resistance to mechanical impact, such as direct underground burial, municipal utility tunnels, and public infrastructure projects in basements. This product combines three core advantages: robust mechanical protection against crushing and puncture provided by double-steel-tape armor; Class B enhanced fire safety performance featuring bundled flame retardancy and LSZH characteristics; and high-temperature XLPE insulation that ensures reliable current-carrying capacity for underground burial. It effectively addresses two critical challenges in underground public infrastructure design: the risk of mechanical damage to cables during installation and the safety hazards posed by toxic smoke in the event of a fire within confined underground spaces.

As a specialized manufacturer of WDZBN-YJY73 armored cables—holding both domestic CCC certification and international IEC qualifications for mechanical and fire safety testing—we offer a comprehensive range of standardized Low-Smoke Zero-Halogen (LSZH) armored cables, full documentation support for acceptance and certification, and dedicated technical consulting for underground electrical engineering. We serve global municipal utility tunnel contractors, industrial park construction groups, commercial real estate design institutes, and procurement teams for large-scale underground projects. We help underground public infrastructure projects—requiring moderate fire-resistance ratings—successfully pass mechanical performance spot checks and fire safety inspections, ensuring long-term, stable, low-maintenance, and cost-effective operation of underground power distribution circuits throughout the building's lifecycle.