What is the Flame Retardancy Testing Method for Wires -Practical Analysis Based on the RSB-WC Equipment

1 Introduction
In power transmission and electronic equipment applications, the flame retardancy of wires and cables is a key barrier to preventing fire accidents. If the flame retardancy of cables is not up to standard, once a short circuit, overload, or aging occurs, it is likely to cause flame spread, release toxic smoke and high-temperature droplets, resulting in serious casualties and property losses. Therefore, establishing standardized and accurate flame retardancy testing methods for wires is crucial.
The LISUN RSB-WC Single Wire and Cable Burning Tester is a professional equipment designed for testing the combustion characteristics of single insulated wires and cables (details link: https://www.lisungroup.cn/products/4137.html). Integrating imported core components and automated control technology, it is widely used in household, industrial, household appliance supporting, testing and certification scenarios. Centering on the two core issues of “What is the working principle of the single wire and cable burning tester” and “What is the flame retardancy testing method for wires”, this paper conducts a systematic analysis combined with equipment parameters and standard systems to provide technical support for industry testing practices.

2 Basic Characteristics of the RSB-WC Single Wire and Cable Burning Tester
2.1 Core Equipment Parameters
The RSB-WC burning tester includes two models: RSB-WC and RSB-WC1, which are adapted to different testing scenarios. Its core technical parameters are shown in the following table:

2.2 Equipment Configuration Requirements
When the RSB-WC and RSB-WC1 models are in operation, they need to be equipped with a dedicated air compressor:
For 220~240V/50Hz voltage scenarios: LS-EU800W2-55L air compressor (power 800W×2, capacity 55L, speed 1380r/min, pressure 0.7Mpa, flow rate 120L/min);
For 110~120V/60Hz voltage scenarios: LS-US800W2-55L air compressor (same parameters as LS-EU800W2-55L).

3 What is the Working Principle of the Single Wire and Cable Burning Tester
Based on the core logic of “simulating real fire environments and automatically monitoring key indicators”, the RSB-WC Single Wire and Cable Burning Tester achieves accurate detection of cable combustion characteristics through the collaborative work of mechanical structure, control module, and sensing system. Its working principle can be divided into four core links:
3.1 Flame Generation and Stable Control
The equipment adopts a 1kW nominal premixed flame burner to generate a standard flame through precise proportioning of gas and air. Gas (high-purity propane or liquefied petroleum gas) is adjusted to a flow rate of 0.1~1L/min through a flow meter, and air is delivered by a compressor and mixed at a flow rate of 3~30L/min to ensure that the flame shape and temperature meet the test standard requirements. The imported flame control module can real-time monitor the flame status, avoiding flame instability caused by gas pressure fluctuations, and ensuring the consistency of test conditions.
3.2 Sample Positioning and Combustion Action
After cutting the sample to a length of 600±25mm, it is vertically fixed on the bracket in the combustion chamber, with the lower end accurately aligned with the flame center. The combustion chamber adopts a smoke-corrosion-resistant iron plate spraying process, which can withstand long-term high-temperature testing and acid smoke erosion. At the same time, it provides a closed environment for the combustion process, simulating the combustion scenario of cables in actual use and avoiding external air flow interference with test results.
3.3 Automated Monitoring of Process Parameters
The equipment integrates imported timing units and sensing systems to achieve real-time monitoring of multi-dimensional parameters:
Combustion time control: Set the combustion duration of 0.1~999.9s through the LCD touch screen. After reaching the set time, the burner automatically moves away, and the afterburning time and glowing time are recorded synchronously;
Flame spread monitoring: Capture the distance and speed of upward and downward flame spread through visual recognition and scale positioning;
Dropping monitoring: Place absorbent cotton 100mm below the sample, judge whether the droplets ignite the absorbent cotton through the sensing module, and record the frequency and characteristics of droplet generation.
3.4 Data Recording and Visual Presentation
Data such as combustion time, afterburning time, glowing time, flame spread distance, and droplet status during the test are real-time displayed and automatically stored through the self-developed LCD touch screen, supporting data export and traceability, avoiding manual recording errors, and ensuring the repeatability and credibility of test results.

4 What is the Flame Retardancy Testing Method for Wires——Standardized Process Based on the RSB-WC Equipment
Based on the working principle of the RSB-WC burning tester, the flame retardancy test of wires follows a standardized process of “preparation – test – determination”, which fully complies with the requirements of core domestic and international standards. The details are as follows:
4.1 Test Preparation Stage
Sample Preparation: Select the single insulated wire or cable to be tested, cut it to a length of 600±25mm, remove surface impurities and damages, and ensure the integrity of the insulation layer. The sample specifications must meet “conductor diameter ＞0.8mm or cross-sectional area ＞0.5mm²”; for fine cables (such as enameled wires with conductor diameter ＜1mm), the RSB-WC1 model should be selected.
Equipment Commissioning: Connect the adapted air compressor, adjust the pressure to 0.7Mpa to ensure stable air flow; connect the gas and set the initial flow rate through the flow meter, ignite the burner to calibrate the flame to a 1kW premixed flame; set the combustion time (such as 30s, 60s, adjusted according to test standards) through the touch screen.
Sample Fixation: Vertically install the prepared sample on the bracket in the combustion chamber, ensure that the lower end of the sample is aligned with the flame center, and place dry absorbent cotton 100mm below to detect the ignition characteristics of droplets.
4.2 Test Execution Stage
After starting the equipment, the burner flame accurately acts on the lower end of the sample, and the timing unit starts recording the combustion time synchronously;
After reaching the set combustion time, the burner automatically moves away from the sample, and the equipment switches to the “afterburning/glowing monitoring” mode to record the afterburning time before the flame is extinguished and the glowing time of the red-hot area of the sample;
During the test, observe and record the flame spread in real time: measure the distance from the lower edge of the upper bracket to the starting point of the carbonized part, and the distance that the combustion extends downward to the lower edge of the upper bracket;
Observe the generation of droplets: record whether droplets are generated, the frequency of droplets, and whether the absorbent cotton is ignited.
4.3 Result Determination Stage
According to the reference standards, the flame retardancy of the sample is judged as qualified or not from three core dimensions: flame spread, combustion duration, and droplet characteristics. The specific judgment indicators are shown in the following table:

4.4 Reference Standard System
The RSB-WC burning tester is compatible with a number of core domestic and international test standards, covering all scenarios of flame retardancy testing for single wires and cables. The standard system is shown in the following table:

5 Typical Application Scenarios of the RSB-WC Burning Tester
5.1 Wire and Cable Manufacturing Industry
It is used for quality control of household wires and cables (such as RVV polyvinyl chloride insulated flexible cables, BV copper core polyvinyl chloride insulated wires) and industrial cables (such as YJV cross-linked polyethylene insulated cables, VV polyvinyl chloride insulated cables). It verifies their vertical combustion performance and droplet characteristics to ensure compliance with safety standards and avoid fire hazards.
5.2 Household Appliance Supporting Industry
For the internal wiring of large household appliances such as washing machines, air conditioners, and refrigerators, as well as the power connection lines of small household appliances such as rice cookers and electric kettles, it tests their combustion performance under flame conditions to meet the safety requirements of “fire prevention of insulated wires and cables inside household appliances” in the household appliance industry and reduce the fire risk caused by equipment failures.
5.3 Testing and Certification Field
Third-party testing institutions such as SGS and CQC use this equipment to carry out compliance testing, providing cable enterprises with test reports that meet CE and CCC certification requirements; enterprises can optimize flame retardant formulas (such as adjusting the addition amount of flame retardants) through this equipment during the R&D stage to improve product competitiveness.
5.4 Special Testing for Fine Wires and Cables
The RSB-WC1 model is specially designed for fine insulated wires inside electronic instruments and communication equipment. It meets the requirements of vertical flame propagation characteristics testing of fine cables under diffusion flame, ensuring the fire safety of internal wiring of electronic equipment.

6 Conclusion
Through the working principle of “stable flame control, precise process monitoring, and automatic data recording”, the RSB-WC Single Wire and Cable Burning Tester provides a standardized solution for wire flame retardancy testing. Its testing method based on vertical burning test covers the entire process of sample preparation, equipment commissioning, test execution, and result determination, complying with the requirements of core domestic and international standards. It can accurately evaluate the combustion performance, flame spread rate, and droplet characteristics of cables. The equipment is widely used in production and manufacturing, household appliance supporting, testing and certification fields, providing reliable technical support for cable quality control and safety assessment. In the future, with the development of flame retardant material technology, the adaptability and testing accuracy of this equipment will be further improved, continuously contributing to the safety upgrade of the wire and cable industry.