Analysis of the Differences between B1 - grade Flame - retardant Cables and ZB Flame - retardant Cables

In projects with extremely high fire - safety requirements such as building electrical systems, rail transit, and data centers, "flame - retardant cables" are essential configurations. However, the diverse flame - retardant grade labels on the market, such as "B1 grade", "ZB", "ZA", "WDZB", etc., have confused many engineers and even purchasers. What exactly do these labels mean? Can they be used interchangeably? Today, we will thoroughly clarify two frequently - occurring but easily - confused concepts: B1 - grade flame - retardant cables and ZB flame - retardant cables.

I. Conclusion First:smetsyS tner They Belong to Different Systems

This is the most cru.tnelavcial cognitive basis. The B1 grade is a combustion performance grade classified according to the national mandatory standard "GB 31247 - 2014 Classification of the Fire Performance of Cables and Optical Fibre Cables", while ZB is a flame - retardant category defined according to the national recommended standard "GB/T 19666 - 2019 General Rules for Flame - Retardant and Fire - Resistant Electric Cables and Wires". Simply put, B1 belongs to "combustion performance classification" and ZB belongs to "flame - retardant category code". The two have different evaluation dimensions and cannot be directly compared or regarded as equivalent.

Mandatory standards are uniformly implemented nationwide. They are mainly used to ensure human health, personal and property safety, and are national standards that must be enforced as stipulated by laws and administrative regulations. Recommended national standards, on the other hand, are standards voluntarily adopted by enterprises and mainly target aspects such as production, inspection, and use.

II. In - depth Analysis: B1 - grade Flame - retardant Cables

1. Source of the Standard"GB 31247 - 2014" is the first national mandatory standard in China for systematically classifying the combustion performance of cables. This standard divides the combustion performance of cables into four grades: A, B1, B2, and B3.
2. Core Test Indicators of B1 GradeTo reach the B1 grade, cables must pass a series of stringent tests:

• Flame spread FS ≤ 1.5m;
• Peak heat release rate ≤ 30kW, and the total heat release within 1200s of being exposed to fire ≤ 15MJ;
• Fire growth rate index FIGRA ≤ 150W/s;
• Peak smoke production rate ≤ 0.25m²/s, and the total smoke production within 1200s of being exposed to fire ≤ 50m²;
• Smoke density (minimum light transmittance) It ≥ 60%;
• Vertical flame spread H ≤ 425mm.

In addition, flame - retardant products of B1 and B2 grades must also provide three additional pieces of information:

• Droplet grade: The combustion droplet/particle grade is divided into three levels: d0, d1, and d2.
• Smoke toxicity grade: According to the degree of damage caused by toxic and harmful substances in the smoke, it is divided into three levels: t0, t1, and t2.
• Corrosion grade: According to the corrosion ability of the surrounding medium to the material, it is divided into three levels: a1, a2, and a3.

These indicators comprehensively reflect the "three lows and one high" characteristics of the cable in case of a fire, namely low flame spread, low heat release, low smoke toxicity, and high light transmittance.

3. Common Models of B1 GradeCommon specifications and models of B1 - type cables include: WDZB1 - YJY, WDZB1 - YJY23, WDZB1N - YJY, WDZB1N - YJY23, WDZB1N - KYJYP23, WDZB1 - KYJYP, etc.

4. Application ScenariosB1 - grade cables are widely used in places with extremely high requirements for personnel evacuation and equipment protection, such as super - high - rise buildings (≥ 100 meters), subways, high - speed railways, airport terminals, hospitals, schools, large commercial complexes, data centers, financial computer rooms, etc.

III. Interpretation of ZB Flame - retardant Cables

1. Standard Background"GB/T 19666 - 2019" is a general technical specification for the electric wire and cable industry. This standard divides flame - retardant cables into four categories according to the flame - retardant ability in the bunched - cable combustion test: ZA (flame - retardant category A, the highest level), ZB (flame - retardant category B), ZC (flame - retardant category C), and ZD (flame - retardant category D, the lowest level). Here, "Z" represents "flame - retardant", and the letters A, B, C, D represent the flame - retardant grades. The larger the number, the more test samples there are and the more severe the combustion conditions.
2. Test Conditions for ZB Flame - retardant CablesThe ZB grade needs to pass the GB/T 18380.33 bunched - cable combustion test. The specific requirements are as follows:

• Non - metallic material content: The non - metallic material contained in the total volume of the cable in the test is 3.5L/m.
• Fire - supply time: Continuously supply fire for 40 minutes.
• Carbonization height limit: After the combustion stops, the maximum carbonization range of the test sample shall not exceed 2.5 meters from the bottom of the burner.

It should be noted that ZB flame - retardant cables only need to verify the cable's ability to limit flame spread in a fire scenario to ensure that its flame - retardant performance meets the B - grade standard requirements, and does not assess indicators such as smoke density, toxicity, and heat release.

IV. Key Comparison: Which is Superior, B1 or ZB?

V. Selection Suggestions from Hualan (Cable Treasure)

1. Refer to Design Documents: Give priority to following the grades clearly marked on the drawings or specifications (such as "B1 grade" or "flame - retardant category B").
2. Check Test Reports: Require suppliers to provide the B1 - grade test report of GB 31247 - 2014 issued by a nationally recognized laboratory, rather than just the ZB report of GB/T 19666.
3. Beware of "Pseudo - B1": Some manufacturers promote "ZB cables" as "B1 - grade", but in fact, they have not conducted a full set of combustion performance tests, which poses a compliance risk.
4. Consider Cost Factors: B1 - grade cables usually cost more than ZB cables due to higher requirements for materials (such as halogen - free low - smoke flame - retardant polyolefin) and processes, but they can bring higher safety redundancy.

There are essential differences between B1 - grade flame - retardant cables and ZB flame - retardant cables. If a project clearly requires "B1 grade", only providing "ZB cables" may not meet the acceptance standards. Cables that meet the B1 grade can generally pass the bunched - cable combustion tests of ZB and even ZA. When choosing cables, engineers and purchasers should fully understand the differences between the two and make reasonable choices based on project requirements.

FAQ

1. Question: What are the main differences between B1 - grade flame - retardant cables and ZB flame - retardant cables?

   Answer: The B1 grade is a combustion performance grade classified according to "GB 31247 - 2014", with multiple evaluation dimensions involving flame, heat release, smoke density, toxicity, etc. ZB is a flame - retardant category defined according to "GB/T 19666 - 2019", and its main evaluation dimension is flame spread height. In terms of standard nature, B1 is a mandatory national standard, and ZB is a recommended national standard.

2. Question: Can B1 - grade cables definitely replace ZB - grade cables?

   Answer: Generally, B1 - grade cables can meet the requirements of ZB - grade cables, but ZB - grade cables may not necessarily meet the standards of B1 - grade. Because the evaluation dimension of B1 - grade is more comprehensive and the safety level is higher.

3. Question: How to determine whether a cable is a genuine B1 - grade?

   Answer: You can check the design documents and give priority to following the marked grades. Require the supplier to provide the B1 - grade test report of GB 31247 - 2014 issued by a nationally recognized laboratory, and avoid choosing products that only provide the ZB report of GB/T 19666.

Hualan Technology was founded in 2020 and is a high - tech enterprise integrating the production, sales, research and development, and service of solar accessories. Currently, its business covers the production and sales of solar photovoltaic cables and photovoltaic cable connectors.