Essential knowledge for wire and cable inspection - Burning test of bundled wires and cables

I. Inspection Purpose

With the development of the economy, the application of flame-retardant cables is becoming increasingly widespread, and the requirements for the flame-retardant performance of cables are also getting higher and higher. The combustion test of bundled wires or cables is mainly used to evaluate the ability of bundled cables to suppress the spread of flames under specified conditions.

Ii. Scope of Application

It is applicable to the bundled burning test of wires and cables.

Iii. Inspection Basis

GB/T 18380.31-2022/IEC 60332-3-10:2009

GB/T 18380.32-2022/IEC 60332-3-21:2009

GB/T 18380.33-2022/IEC 60332-3-22:2009

GB/T 18380.34-2022/IEC 60332-3-23:2009

GB/T 18380.35-2022/IEC 60332-3-24:2009

GB/T 18380.36-2022/IEC 60332-3-25:2009

Iv. Test Equipment and Apparatus

1. Combustion test chamber

2. Gas source (propane gas).

V. Sampling and Testing Equipment

The sample consists of several cables of the same length, with the minimum length of each cable being 3.5 meters.

2. The number of samples should be such that the total volume of non-metallic materials contained per meter is 7L (Class A).

3. The number of samples should be such that the total volume of non-metallic materials contained per meter is 3.5L (Class B).

4. The number of samples should be such that the total volume of non-metallic materials contained per meter is 1.5L (Class C).

Vi. Test Procedures

Test conditions: The external wind speed should not exceed 8m/s, the temperature of the inner wall of the box should be between 5 and 40℃, and the box should be dry.

The samples should be treated at 23±5℃ for at least 16 hours.

3. Install the prepared samples on the steel ladder in accordance with the standard requirements.

4. Start the test according to the fire supply time stipulated in the standard.

5. After the combustion stops, wipe the sample clean. If the sample continues to burn for 1 hour after the fire supply is stopped, forcibly extinguish the flame.

Vii. Evaluation of Test Results

The maximum distance of the carbonized part measured on the sample should not exceed 2.5 meters above the bottom edge of the blowtorch.