I. BTLY Cable Product Standards:
BTLY fire-resistant cables are manufactured in accordance with the following standards:
Items: GB/T, IEC, DIN, VDE, BS
Cable insulation level and withstand voltage rating: 12706, 60502
Flame test and mechanical test: 6027
Flame spread test: 18380.3, 60332-3, 472
Smoke emission test: 17651.2, 61034-2, 472
Circuit integrity test: 12666.6, 60331, 472, 6387
Halogen content test: 17650.2, 60754-2, 472
Flame test for electrical cable systems: 4102
China's promulgated standards and regulations primarily include:
"Code for Fire Protection Design of High-Rise Civil Buildings" GB50045-95 (2005 Edition)
Beijing Civil Building Wire and Cable Fire Protection Design Code (DGJ08-93-2002)
Building Design Fire Protection Code (GB 50016-2006)
China Fire Protection Manual (2007 Edition)
Design Code for Automatic Fire Alarm Systems (GB 50116-98)
Fire Protection Design Code for Wire and Cable in Civil Buildings (DGJ08-93-2002)
Beijing Fire Department Document (Beijing Fire and Rescue Department 2004) 352
Design Code for Power Engineering Cables (GB 50127-94)
Fire Protection Design Code for Garages, Repair Garages, and Parking Lots (GB 50067-97
BTLY Cable Flame Test Standards
The design parameters of BTLY fire-resistant cables strictly adhere to the British BS6387 standard and the International Electrotechnical Commission (IEC) standard. These technical parameters have passed special testing by the China Fire Protection Administration and the National Fire-Resistant Building Materials Quality Supervision and Inspection Center.
Because fire-resistant cables are composed entirely of inorganic materials (metallic copper and magnesium oxide powder), they are inherently fire-resistant and cannot burn or support combustion. Since the melting points of copper are 1083°C and magnesium oxide are 2800°C, these cables can continue to provide power even in fires near the melting point of copper, making them truly fire-resistant.
II. BTLY Cable Structure
The conductor is a round stranded copper wire; the insulation is pure gold mica tape (no longer composited with extruded insulation, thus eliminating carbon particles and improving electrical stability); an interlocking metal sheathed aluminum alloy insulation layer (which can be used for grounding); and an insulation sheath (covered with an inorganic material—Mg(OH)2 or Al(OH)2—that is flame-incombustible, expandable, and fire-retardant).
III. BTLY Cable Applications
The NG-A (BTLY) flexible fire-resistant cable is suitable for emergency use after installation. It can also be used as a 125°C halogen-free flame-retardant or fire-resistant cable. This cable series has a wide coverage range, overcoming the shortcomings of rigid fire-resistant cables while leveraging the advantages of flexible fire-resistant cables. It provides practical products for key projects, enabling modern engineering to achieve the goal of preventing short circuits from burning and burning from short circuits in electrical wiring. It is not only successfully applied to fire alarm and emergency lifeline circuits, but is also widely used in high-density current and other special performance requirements. IV. Features ① Fire resistance meets the three BS6387 tests: no breakdown under 950°C flame for 3 hours, no damage after 30 minutes at 650°C, and no damage after 15 minutes of water spray (direct immersion is also acceptable). This fully meets the BTT fire resistance standards.
IV. BTLY Cable Features
② This product is available in sizes of 1.5-6 square meters with 1-37 cores, 10-240 square meters with 1-5 cores, and 300-630 square meters with single cores. Lengths can be customized and delivered as whole reels without joints.
③ No separate conduit is required for installation, and the cable offers the same waterproof and impact resistance as BTT.
④ Excellent rodent, ant, and radiation protection ensures cable stability, long life, and durability.
⑤ Low operating temperature, low line loss, strong overload resistance, long service life, and high safety make it particularly suitable for use in projects with environmental protection requirements.
⑥ Explosion-proof (The highly compacted insulation material in the cable and the cable terminals with specially sealed sleeves prevent steam, gas, and flame from entering connected electrical equipment, making it suitable for use in explosion-hazardous areas and for connecting various explosion-proof equipment and devices.)
⑦ Corrosion-resistant (The metal sheath of the BTLY model mineral insulated cable is highly corrosion-resistant, eliminating the need for additional protective measures in most installations. Even in locations where the cable's metal sheath is susceptible to chemical corrosion or severe industrial pollution, the cable remains safe due to the protection of the outer plastic sheath.)
⑧ High mechanical strength (BTLY mineral insulated cable is durable and can continue to operate even if deformed by one-third of its diameter. Even withstanding severe mechanical damage, its electrical performance remains unaffected.)
V. Main Functions of BTLY Cable
NG-A (BTLY) model cable uses aluminum as its primary material. Extrusion of the metal tube replaces drawing of the copper tube, simplifying the process and improving efficiency while significantly reducing product costs (aluminum costs only 1/10 of the overall cost of copper). The reason aluminum tubes can replace copper tubes and resist melting under high-temperature flames is due to the intumescent refractory layer extruded over the tubes. Under the attack of flames, the intumescent layer foams and solidifies, forming a thick barrier that blocks the flames from directly impacting the tubes. This not only preserves the integrity of the tubes but also reduces the heating temperature of the mica tape to below 600°C, undoubtedly improving the insulation stability of the mica tape (the insulation resistance of mica tape increases with decreasing temperature).
VI. BTLY Cable Models and Specifications
For conductor sizes of 120 mm² and above, single-core cable is recommended for ease of installation.
Model Description Example
1. Type Code
Fire Resistance ……………………………………N
Insulation ……………………………………G
Grade ……………………………………A (950°C~1000°C) 3 hours
Wiring Series …………………………B
2. Conductor Code
Copper Conductor ……………………………T
3. Insulation Code
Mica Insulation ……………………………Omitted
4. Metal Sheath Code
Aluminum Metal Sheath ……………………………L
Aluminum Alloy Metal Sheath …………………LH
Copper Metal Sheath ………………………T
Copper Alloy Metal Sheath …………………TH
5. Sheath Code
Polyethylene/Polyolefin …………………Y
※To comply with local acceptance standards, functional codes such as WDZAN, WDZN, NH, or ZR may be added to the front of the model number. The actual products remain the same.
7. BTLY Product Examples
Isolated (flexible) mineral insulated cable, rated voltage 0.6/1kV, 4-core, nominal cross-section 120mm², represented as:
NG-A (BTLY) 0.6/1kV 4×120
Isolated (flexible) mineral insulated cable, rated voltage 0.6/1kV, 1-core, nominal cross-section 240mm², represented as:
NG-A (BTLY) 0.6/1kV 1×240
Referred to as NG-A or BTLY, also known as NG-A (BTLY), WDZAN-BTLY, NG-A, WDZAN-BTLV, BTLV, BTLYQ, BTLVQ, etc.
1. Conductor: Made of twisted multiple copper wires with excellent bending properties.
2. Insulation: Made of mineral insulating material.
3. Metal Sheath: Utilizes a soft aluminum sheath, processed through a special process, offering excellent electrical conductivity, mechanical impact resistance, and flexible bending properties (can replace a ground wire).
4. Isolation Sleeve: Utilizes a cross-linked polyethylene waterproof barrier.
5. Oxygen Barrier: Utilizes Mg(OH)2 or Al(OH)2 mineral materials for high-temperature resistance and fire resistance.
6. Outer Sheath: Utilizes a low-smoke, non-toxic, or higher-quality plastic material with excellent corrosion resistance. Different material grades are available upon request.
8. Comparison of Applicable Standards and Specifications for BTLY Cables
GB/T 12706 "Power Cables and Accessories with Extruded Insulation, Rated Voltage 1 kV (Um = 1.2 kV) to 35 kV (Um = 40.5 kV)", GB/T 17651 "Determination of Smoke Density of Electric or Optical Fiber Cables Burning under Specific Conditions", GB/T 18380 "Fire Tests for Electric and Optical Fiber Cables Under Fire Conditions", GB/T 19216 "Line Integrity Tests for Electric or Optical Fiber Cables Under Fire Conditions", GA 306 "Flame Retardant and Fire Resistant Cables - Classification and Requirements for Plastic Insulated Flame Retardant and Fire Resistant Cables", and British Standard BS 6387 "Fire Test Methods for Cables to Maintain Line Integrity Under Fire Conditions".
9. BTLY cable laying conditions and applicable occasions
BTLY cable can be laid in transmission and distribution lines in important places such as tunnels, cable trenches, bridges, trough boxes, shafts, high-rise buildings, rail transit, hospitals, shopping malls, exhibition halls, garages, entertainment venues, data centers, etc.
BTLY cable characteristics
(1) BS6387 fire resistance
① 950℃: No breakdown after continuous power on for 180 minutes under flame (C)
② 650℃: No breakdown after 15 minutes of water spraying under flame (W)
③ 950℃: No breakdown after 15 minutes of knocking and vibration under flame (Z)
(2) Sustainable production
The metal sheath continuous forming process used in the production process of NG-A (BTLY) isolated (flexible) mineral insulated cable enables the continuous length of a single cable to meet customer requirements, so that the entire cable has no joints and can be laid in sections during installation without the need for conduit. (3) Wide range of specifications
The conductor of NG-A (BTLY) isolated (flexible) mineral insulated cable is round copper stranded wire, so the nominal cross-section of 2.5~6 mm2 can produce 3-61 cores, 2.5~150 mm2 can produce 2-5 cores, and 10~300 mm2 can produce single core.
(4) Short delivery cycle
Adopting advanced production process and mature manufacturing technology, the delivery cycle of NG-A (BTLY) isolated (flexible) mineral insulated cable is short, and the fastest delivery time for conventional models is 7 working days.
(5) Voltage level
Mica tape insulation can make the rated voltage of NG-A (BTLY) isolated (flexible) mineral insulated cable reach 0.6/1kV.
(6) Waterproof NG-A (BTLY) isolated (flexible) mineral insulated cable adopts the metal sheath continuous molding process, which can achieve no joints in the middle, eliminating the phenomenon of water ingress at the joints. Even if the cable is completely immersed in water, it can still operate normally. (7) Anti-mosquito NG-A (BTLY) isolated (flexible) mineral insulated cable can effectively prevent the electrical damage of the cable insulation core by rats and mosquitoes due to the presence of the continuously molded metal sheath. (Damage to the outer sheath can be repaired and restored) (8) High mechanical strength NG-A (BTLY) isolated (flexible) mineral insulated cable is strong and durable, and its impact resistance under fire conditions is better than that of ordinary steel belt armored cable. (9) Strong overload capacity NG-A (BTLY) and BBTRZ flexible mineral insulated cables are completely insulated with mica tape mineral tape that is resistant to high temperatures exceeding 800℃, so its short-circuit overload capacity is higher than that of conventional YJV cables. (10) Corrosion resistance
The metal sheath of NG-A (BTLY) isolated (flexible) mineral insulated cable has high corrosion resistance and generally does not require additional protective measures. Even in places where the cable is susceptible to chemical corrosion or severe industrial pollution, it is still safe because the outermost layer of the cable is protected by a plastic outer sheath.
(11) Energy saving and environmental protection
The heat dissipation of the core of NG-A (BTLY) isolated (flexible) mineral insulated cable is better than that of other types of cables. Therefore, during normal operation, the line loss of NG-A (BTLY) isolated (flexible) mineral insulated cable is 4~7% lower than that of conventional cables.
(12) Radiation protection and long service life (safe and reliable)
The inorganic mineral materials and metal sheaths used in NG-A (BTLY) isolated (flexible) mineral insulated cable have a radiation resistance far higher than the plastic insulation and sheath of organic cables, which can ensure the long-term stability of the cable and is suitable for the nuclear power field. (Our company has the qualification to bid for cables on the procurement platform of China General Nuclear Power Group Co., Ltd.)
(13) Instructions for using metal sleeves as grounding cores
Make clear statements in the ordering contract, and the contract quotation shall be based on this; when using metal sleeves as grounding cores, the aluminum sleeves of each core must be connected in parallel with connectors; the grounding connector and the aluminum sleeve must be properly tightened and sealed with heat shrink tubing, and photos must be kept for record; the grounding connector constructor must keep files for easy tracing.
(14) Intermediate joints
If the cable is damaged during construction, an intermediate joint connector is required, which is directly supplied by the manufacturer and assisted in installation.
X. Recommendations for selecting BTLY cable cross-sections
1. Select cross-section according to core temperature rise
When the load current passes through, the core temperature does not exceed the long-term operating temperature allowed by the cable insulation. This is usually referred to as selecting according to the allowable current carrying capacity.
Suggestion: When the cable passes through different heat dissipation conditions, the corresponding core operating temperature will be different. The cross-section should be selected according to the worst heat dissipation condition (usually no more than 1 meter). 2. Select cross-section based on the allowable voltage loss range.
When the actual terminal voltage of electrical equipment deviates from the rated value, its performance will be affected. The extent of the impact depends on the magnitude and duration of the voltage deviation.
Recommendation: Because the voltage loss increases dramatically during a fire, the core temperature rises sharply. Therefore, voltage loss should be calculated based on fire conditions to ensure continued operation of critical equipment.
Due to the excellent thermal insulation and heat dissipation properties of NG-A (BTLY) cable, it is sufficient to enlarge the cable size by one or two levels based on normal conditions. This generally meets the requirement of a voltage deviation of no more than -10% under fire conditions.
