The difference between A, B1, B2 flame-retardant cables and ZA, ZB, ZC, ZD flame-retardant cables

1. Different Reference Standards

Traditional Bundled Flame Retardant ZA, ZB, ZC and ZD Classes do not belong to the classification of flame retardant performance. The flame retardant levels of ZA, ZB, ZC, and ZD refer to GB/T 19666-2019 “General Rules for Flame Retardant and Fire Resistant Wires, Cables, or Optical Cables”, which are divided into four categories: ZA, ZB, ZC, and ZD according to the combustion characteristics; the flame retardant levels of A, B1, B2, and B3 refer to GB 31247-2014 “Classification of Burning Performance of Cables and Optical Cables”, which are divided into four grades: A, B1, B2, and B3 according to the flame spread length, peak heat release during combustion, total heat release, combustion speed, peak smoke generation speed, total smoke generation in 20 minutes, and smoke concentration.

2. Different standards binding force
   GB 31247 “Classification of Burning Performance of Cables and Optical Cables” is a national mandatory standard with mandatory binding force. Products that do not meet the mandatory standards shall not be produced, sold, or imported. Click here to learn more about cable technology and make progress every day. GB/T 19666-2019 “General Rules for Flame Retardant and Fire Resistant Wires, Cables, or Optical Cables” is a recommended standard encouraged by the state. Mandatory standards are unified standards throughout the country, standards to protect human health, personal and property safety, and national standards that are enforced by laws and administrative regulations; recommended national standards are voluntarily adopted standards, mainly for production, inspection, use and other aspects.
3. Different technical requirements
   The most important is the technical requirements of B1 flame-retardant wires and cables, from which we can clearly understand the excellent performance of these indicators in safety performance.
   Standards for combustion performance:
4. Flame spread FS≤1.5m;
5. Peak heat release rate ≤30kW; total heat release within 1200s of fire ≤15MJ;
6. Combustion growth rate index FIGRA≤150W/s;
7. Peak smoke production rate ≤0.25m²/s; total smoke production within 1200s of fire ≤50m²;
8. Smoke density (minimum light transmittance) It≥60%.
9. Vertical flame spread H≤425mm

The product must provide three additional information:
(1) Droplet level: The burning droplet/particle level is divided into three levels: d0, d1, and d2.
(2) Smoke toxicity level: According to the degree of damage/damage caused by toxic and harmful substances in the smoke, it is divided into three levels: t0, t1, and t2.
(3) Corrosiveness level: According to the ability of the surrounding medium to corrode the material, it is divided into three levels: a1, a2, and a3. Special attention should be paid to the additional information that must be indicated for B1 and B2 flame retardant products; such as: GB 31247 B1 (d0, t0, a1). If it is not marked, it is regarded as a B3 flame retardant product, that is, ordinary low-smoke halogen-free wires and cables.

B1-level flame-retardant wires and cables are applicable to GB 51348-2019 “Electrical Design Standards for Civil Buildings”. When direct wiring is used in indoor places, the following provisions shall be met:

1. Flame-retardant sheathed insulated wires of not less than B2 level shall be used, and the cross-sectional area shall not be greater than 6mm;
2. Fire-resistant cables and mineral insulated cables shall have flame retardancy performance not less than B1 level.

The selection and laying of fire distribution lines shall meet the requirements for the continuous operation time of fire-fighting electrical equipment (750℃, 90min) and comply with the following provisions:

1. The alarm bus of the automatic fire alarm system in the evacuation passage of crowded places shall select cables with combustion performance of B1 level;
2. The alarm bus in other places shall select cables with combustion performance not less than B2 level;
3. Fire linkage bus and linkage control line shall select fire-resistant copper core cables; the combustion performance shall comply with the provisions of GB 31247.