Many people easily confuse the concepts of flame-retardant cables and fire-resistant cables. Flame-retardant cables, which often feature advantages like low halogen and low smoke, are particularly suitable for use in chemical plants. However, while fire-resistant cables can generally replace flame-retardant cables in many applications, the reverse is not true. Their main differences are as follows:

1. Difference in Principle

The working principles of fire-resistant and flame-retardant cables differ.

• The flame-retardant principle of halogenated cables relies mainly on the flame-inhibiting effect of halogens.

• The flame-retardant principle of halogen-free cables depends on the endothermic effect of precipitated water, which lowers the temperature to extinguish flames.

• Fire-resistant cables rely on the mica material within the fire-resistant layer to provide fire protection and heat resistance, ensuring the cable can continue to operate normally during a fire.

2. Difference in Structure and Materials

The structure and materials used in fire-resistant cables differ from those in flame-retardant cables.

• The basic structure of a flame-retardant cable consists of:
  (1) Insulation layer made from flame-retardant materials.
  (2) Sheath and outer jacket made from flame-retardant materials.
  (3) Binding tapes and fillers made from flame-retardant materials.

• Fire-resistant cables typically have an additional fire-resistant layer between the conductor and the insulation. Therefore, theoretically, a fire-resistant layer can be added to a flame-retardant cable structure to create a flame-retardant and fire-resistant cable.

In practice, fire-resistant cables often use multiple layers of mica tape directly wrapped around the conductor. This construction can withstand prolonged burning; even if the polymer at the point of flame application burns away, it ensures the line remains operational.

3. Clear Concepts, Advantages, and Disadvantages of Flame-Retardant, Halogen-Free, and Fire-Resistant Cables

• Flame-Retardant Cables:

  • Characteristic: Delay the spread of flame along the cable, preventing the fire from expanding.

  • Advantage: Due to their lower cost, they are widely used cable types. Whether installed singly or in bundles, when burned, the spread of flame can be controlled within a certain range, thus helping to avoid major disasters caused by fire spread and improving the fire safety level of cable lines.

  • Disadvantage: (Compared to Halogen-Free) May produce more smoke and corrosive/toxic gases when burned.

• Halogen-Free Low-Smoke Flame-Retardant Cables:

  • Characteristic: Not only possess good flame-retardant properties, but the halogen-free materials also result in low corrosivity, low toxicity, and very little smoke generation when burned.

  • Advantage: Reduces damage to personnel, instruments, and equipment, facilitating timely rescue efforts during a fire.

  • Disadvantage: Their mechanical and electrical properties are generally slightly inferior to those of regular cables.

• Fire-Resistant Cables:

  • Characteristic: Designed to maintain circuit integrity for a specified period under flame burning conditions.

  • Advantage: Can ensure the circuit remains operational during a fire. When designed as low-smoke halogen-free types, they emit minimal acidic gas and smoke during combustion, significantly enhancing safety during a fire. Especially, they can maintain circuit integrity even under combined conditions of burning, water spray, and mechanical shock.

  • Disadvantage: Typically higher cost than standard flame-retardant cables.