What is the standard for fire resistant cable?

The IEC standard for cables defines the flame resistance criteria for various cables. To evaluate the flame retardancy, the IEC has developed IEC-1, IEC-2, and IEC-3. IEC-1 and IEC-2 assess the flame retardancy of single cables positioned at an angle and vertically, respectively. IEC-3 addresses the flame retardancy of bundled cables when tested in a vertical position, which imposes stricter criteria than its single-cable counterparts. Cables manufactured by ZMS comply with these standards and pass the necessary assessments.

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Low-smoke Zero Halogen cable is noted for its excellent fire-resistant properties along with the absence of halogens in the materials used. This type of cable is less corrosive and emits minimal smoke when burned, thereby reducing potential harm to individuals and equipment. This feature facilitates easier evacuation during emergencies.
Although low-smoke halogen-free flame-retardant cables have outstanding flame-retardant characteristics, their mechanical and electrical properties may be somewhat lower than those of standard cables.

Application Requirements:
The permissible continuous operating temperature for conventional non-halogen low-smoke flame-retardant polyolefin insulation should not exceed 70C, whereas for irradiation cross-linked non-halogen low-smoke flame-retardant insulation, it should not exceed 105C. Additionally, the minimum temperature for cable installation should be no less than 0C.

Often people confuse flame-retardant cable with fire-resistant cable. While flame-retardant cables have numerous advantages suitable for chemical industries, such as low halogen and low smoke emissions, fire-resistant cables serve a different purpose. The fundamental differences between the two types include:

1. Principle Differences

The underlying principles of fire-resistant and flame-retardant cables vary.
Flame-retardant cables that contain halogens work through the halogen's flame-retardant effects, whereas halogen-free variants function by releasing moisture to cool and extinguish flames. On the other hand, fire-resistant cables rely on a protective layer made of mica materials to ensure the cables continue functioning effectively even during a fire.

2. Structural and Material Differences

Fire-resistant cables are structurally distinct from flame-retardant cables.
Typically, a flame-retardant cable consists of:
(1) An insulation layer made from flame-retardant materials.
(2) A sheath and outer covering made from flame-retardant materials.
(3) A filling and tape constructed from flame-retardant materials.

In contrast, fire-resistant cables include a fire-resistant layer situated between the conductor and insulation. It is theoretically possible to integrate fire-resistant layers into flame-retardant cables to create hybrids, but practical applications do not necessitate this. Fire-resistant cables typically wrap multiple layers of mica tape around the wire directly, providing prolonged resistance to combustion, ensuring the circuit operates correctly even if the outer layer burns.

To evaluate the fire resistance of cables, the IEC has established standards IEC-1, IEC-2, and IEC-3.
IEC-1 and IEC-2 specifically assess flame retardancy for single cables placed at angles and vertically. In contrast, IEC-3 targets the flame resistance testing of bundled cables during vertical burn tests, adhering to notably higher flame retardancy requirements.

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IEC-1/BS-1 Flame Retardant Rating (Flame Tests on Individual Vertical Insulated Wires/Cables)
This rating establishes the flame resistance for individual cables. The test specifies that a 60cm specimen is fixed vertically within a metal chamber. A propane burner applies a flame of 175mm at designated points on the specimen. The test passes if the damaged portion remains confined to a maximum of 50mm below the fixed end.

IEC-3/BS-3 Flame Retardant Rating (Vertical Burn Tests for Bundled Wires or Cables)
This rating defines the flame retardant standard for bundled cables. Testing involves securing a 3.5m cable sample vertically, determined by non-metallic classifications, and under direct flame exposure at specified conditions. The test requires the cable to remain intact during 20 minutes of forced airflow under specified parameters without allowing the flame to propagate beyond 2.5 meters.

Service Offerings: ZMS provides an extensive range of cable and conductor products tailored to your needs. We're dedicated to offering professional support and solutions for all projects.

Quality Assurance Services: Our cable products are produced in compliance with international standards including GB, IEC, BS, NFC, ASTM, and DIN. Our expert team can adapt products to fit your specific requirements.

Professional Customer Service: ZMS offers comprehensive consulting services to aid in project solutions and fast product delivery.

Delivery and Shipping Services: In addition to providing high-quality cables, ZMS excels at delivering safe and efficient product transport while minimizing costs through optimal packaging and logistics.

Packaging Solutions from ZMS: We provide cable packaging on wooden reels, in corrugated boxes, and coiled formats. The ends are securely sealed to prevent moisture damage, and we can label products according to customer specifications using waterproof materials.

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BS (British Standard Institution)

BS-1: Code of practice for emergency lighting of premises

BS-2: Fire detection and alarm systems - Code of practice for system design, installation, commissioning, and maintenance

BS-6: Fire detection and alarm systems in buildings - Code of practice for design, installation, and maintenance in dwellings

BS-8: Fire detection and alarm systems - Code of practice for voice alarm systems

BS-9: Emergency voice communication systems design and installation

BS: Specification for performance requirements of cables for circuit integrity during fire conditions

BS: Non-armoured cables for electric power, lighting, and internal wiring with low emissions of smoke and corrosive gases when burned

BS-6: Specifications for cable systems in smoke and heat control systems

BS-1: Specification for fire-resistant screened cables with low emissions of smoke and corrosive gases, including multicore and multipair cables

BS: Armoured fire-resistant cables for voltages up to 600V with low emissions during combustion

BS-2: Test methods for assessing fire integrity of small cables for emergency circuits.

BS EN: Assessment of fire integrity for large-diameter power cables used in smoke and heat control systems.

BS: Selection and installation guidance for fire-resistant power and control cable systems.

BS: Electric Cable - Low emission insulated armored cables having low emission of smoke and corrosive gases during fire.

BS-1 = IEC 332-1: Test on electric cables under fire conditions - method for single vertical insulated wire or cable.

BS-3 = IEC 332-3: Test on electric cables under fire conditions - test on bunched wires or cables.

BS-1, IEC-1: Method for assessing gases produced during combustion of cables.

BS-2, IEC-2: Testing gas acidity (corrosivity) produced during material combustion.

CEI (Comitato Elettrotecnico Italiano)

CEI 20-11 / EN: Insulating, sheathing, and covering materials for low-voltage energy cables

CEI 20-36/2-1: Tests on electric cables under fire conditions for circuit integrity

CEI 20-45: Fire-resistant elastomeric insulated cables with rated voltage Uo/U 0.6/1 kV

DIN (Deutsches Institut für Normung)

DIN: Fire behavior of building materials and components - Requirements and testing for circuit integrity of electric cable systems.

ASTM Standard

ASTM D: Test method for measuring minimum oxygen concentration supporting combustion of plastic.

ASTM D792: Test methods for density and specific gravity of plastic when displaced.

ASTM D662: Test method for noting smoke density generated by solid materials.

ASTM D638: Standard test method for tensile properties of plastics.

EN (European Norm)

EN: Test methods for resistance to fire of unprotected small cables for emergency circuits.

EN: Tests for vertical flame spread of mounted bunched wires and cables.

EN: Methods to determine halogen acid gas amount from combustion of polymeric materials in cables.

EN: Assessment of gas acidity (corrosivity) during combustion measuring pH and conductivity.

EN -7: Specification for instrumentation and control cables.

EN: Tests for resistance to fire for larger unprotected power and control cables.

IEC (International Electrotechnical Commission)

IEC: Guidance on dimensional limits for conductors of insulated cables.

IEC: Tests for electric cables under fire conditions maintaining circuit integrity.

IEC-1: Tests on electric and optical fiber cables under fire conditions for flame propagation.

IEC-3: Tests for flame spread for veritcally-mounted cables.

IEC-1: Standard for optical fibers.

NBN (Norme Belge)

NBN 713-020: Fire resistance standards for building materials.

NF (Norme Française) SS (Singapore Standard)

SS 299 part 1: Fire-resistant cables performance criteria maintaining circuit integrity under fire conditions.

UL (Underwriters Laboratories)

UL 94: Test for flammability of plastic materials.

VDE (Verband der Elektrotechnik Elektronik Informationstechnik)

VDE: Wiring cables for telecommunication and data processing - Testing cables under fire conditions.