FAQs About Bundle wire and cable burning tester

In the safety performance evaluation and certification of wires and cables, the Bundle Wire and Cable Burning Tester is a standardized testing device specifically designed to evaluate the burning behavior of cable bundles under flame exposure. It simulates real fire conditions in which bundled cables are subjected to heat, ignition, and flame propagation, allowing assessment of their ability to inhibit vertical flame spread when installed in a vertical configuration.

This testing equipment is essential for verifying flame retardancy, fire safety performance, and supporting product design improvement. It is widely used in testing laboratories, cable manufacturers’ internal labs, and certification systems.

This article presents a systematic explanation of key issues related to bundled cable burning tests in the form of Frequently Asked Questions (FAQ), helping readers gain a comprehensive understanding of the working principles, applicable standards, equipment configuration, and test procedures.

What Is a Bundle Wire and Cable Burning Tester?

Q: What exactly is a bundle wire and cable burning tester, and what does it evaluate?

A: A bundle wire and cable burning tester is a device used to evaluate the ability of bundled wires and cables to resist vertical flame spread under specified test conditions. A standardized ignition source is applied to the lower section of vertically mounted cable bundles, exposing them to flame. The test then observes whether flames propagate upward, the rate of flame spread, and flame persistence.

Based on these observations, the flame-retardant performance and fire safety level of the cable bundle are assessed. Test results are used to determine compliance with relevant safety standards and certification requirements.

This equipment is applicable to various types of bundled cables, including power cables, control cables, communication cables, optical fiber cables, and multi-core wire harnesses. The test is conducted under standardized procedures and controlled burning conditions to ensure scientific validity and reliable, repeatable results, making it an important tool for quality control and fire risk assessment.

Why Is Bundle Cable Burning Testing Necessary?

Q: Why must bundled wires and cables undergo burning tests?

A: When wires and cables ignite in a fire environment, their combustion behavior, flame propagation speed, and the generation of smoke and toxic gases directly affect personal safety and property loss. In real fire scenarios, vertically installed cable bundles can easily become pathways for flame spread. If flame propagation is not effectively controlled, the fire can escalate rapidly.

Therefore, evaluating the flame-retardant performance of bundled cables through standardized burning tests is a critical basis for determining cable safety and compliance with installation requirements.

Bundle burning tests not only determine whether cables continue burning after flame exposure but also quantitatively assess parameters such as flame spread height and burning duration. These indicators are essential for classifying flame-retardant grades and understanding flame propagation behavior. Based on test results, manufacturers can optimize material formulations and develop improved flame-retardant designs, while certification bodies can assess compliance with regulatory standards.

What Standards Are Commonly Used for Bundle Burning Tests?

Q: Which standards are typically applied to bundle cable burning tests?

A: Bundle wire and cable burning tests are conducted in accordance with various international and regional safety standards. These standards specify test methods, equipment dimensions, ignition conditions, flame application angles, and evaluation criteria to ensure repeatability and comparability of results. Common standards include:

IEC 60332-3 series: International standards for flame propagation testing of vertically mounted bundled cables

GB/T 18380.31 / GB/T 18380.32: Chinese national standards equivalent to IEC 60332-3. defining test conditions and acceptance criteria

UL 1685: North American standard evaluating flame spread behavior of cable bundles mounted on vertical trays

EN 50399: European standard assessing both burning behavior and smoke generation of bundled cables

IEEE 383 / IEEE 1202 (optional): Applicable on certain testers through adjustment of burner orientation

These standards clearly define details such as burner position, fuel type, airflow conditions, and allowable flame spread limits, forming the technical basis for standardized testing.

What Are the Main Components of the Testing Equipment?

Q: What are the typical components of a bundle wire and cable burning tester?

A: A bundle wire and cable burning tester is a large, specialized system that generally consists of the following components:

Test Chamber

The chamber is typically constructed from heat-resistant stainless steel with a rigid structure. It forms the core testing area where vertical burning of cable bundles takes place.

Bundle Support Structure (Ladder or Tray)

A standardized metal ladder or tray is installed inside the chamber to mount bundled cables vertically. Different standards specify different ladder widths and configurations.

Ignition System (Burner)

The ignition system commonly uses a propane gas burner to generate a stable flame. Burner position, angle, and gas flow rate must be precisely set according to the applicable standard.

Ventilation and Exhaust System

An air supply and exhaust system ensures stable oxygen conditions during combustion and safely removes smoke and combustion gases from the chamber.

Control and Monitoring System

This includes timers, temperature sensors, gas flow controllers, and data recording devices to ensure compliance with standard test conditions and accurate data collection.

Safety Protection Devices

Due to the involvement of high temperatures and combustible gases, the equipment is typically equipped with emergency stop buttons, fire suppression systems, and other safety features to reduce operational risks.

How Is a Bundle Cable Burning Test Conducted?

Q: What is the basic procedure for bundle burning tests?

A: Bundle burning tests are performed according to standardized procedures, generally including the following steps:

Sample Preparation

A specified number of cables are bundled and tied according to standard requirements, with defined lengths and spacing.

Sample Installation

The bundled cables are vertically fixed onto the ladder inside the test chamber, ensuring correct positioning and specified distances from the burner.

Flame Application

The burner is ignited, and a standardized flame is applied to the lower section of the cable bundle for a specified duration and intensity.

Observation and Recording

During the test, flame spread height, burning duration, and combustion behavior are observed and recorded. If equipped, heat release and smoke parameters may also be measured.

Result Evaluation

Test results are evaluated against standard-defined acceptance criteria, such as maximum allowable flame spread height and flame persistence time. Compliance or non-compliance is determined accordingly.

Common Terminology in Bundle Burning Tests

Q: What are some commonly used technical terms in these tests?

Vertical Flame Spread: The height and rate at which flames propagate upward along vertically mounted cable bundles

Heat Release Rate (HRR): The amount of heat released per unit time during combustion, indicating burning intensity

Smoke Production Rate (SPR): The rate of smoke generation during combustion, relevant to visibility and smoke hazard evaluation

Burning Duration: The time a cable continues to burn after the ignition source is removed, reflecting self-extinguishing performance

Which Products Are Suitable for Bundle Burning Tests?

Q: What types of cables or wire harnesses are typically tested?

A: Bundle burning testers are mainly used to evaluate the vertical burning behavior of:

Multi-core power and control cables

Communication cables and optical fiber bundles

Bundled wires with insulation and outer sheaths

Cables used in applications where flame-retardant bundle testing is required, such as building wiring and internal wiring of electrical equipment

Single-cable flame tests are conducted using different instruments. Bundle burning tests focus on simulating real installation conditions and flame propagation behavior in grouped cable layouts.

How Should Test Data Be Interpreted?

Q: Which parameters are most important when evaluating test results?

A: Test results are assessed based on limits specified in applicable standards. Key evaluation parameters include:

Maximum flame spread height

Flame persistence time after burner removal

Presence of flaming droplets or burning debris

If additional instrumentation is used, parameters such as HRR and SPR may be analyzed for a more detailed assessment of fire hazard characteristics.

These indicators collectively reflect whether cables may intensify fire spread, generate excessive smoke, or fail to self-extinguish after ignition.

What Precautions Should Be Taken During Testing?

Q: What should be noted before and during testing?

Standardized sample preparation is essential to ensure comparable results

Environmental conditions such as temperature, ventilation, and gas supply must meet standard requirements

Accurate burner positioning is critical, as distance and angle significantly affect burning behavior

Adequate safety measures must be in place due to open flames and high temperatures

What Are the Limitations of Bundle Burning Tests?

Q: What limitations does this type of test have?

A: Bundle burning tests simulate cable combustion under standardized conditions. While they effectively evaluate flame-retardant performance and flame spread characteristics, they cannot fully replicate the complexity of real fire scenarios, which may involve varying fire sources, structural influences, and environmental factors.

Therefore, these tests serve primarily as standardized comparative assessments rather than exact representations of all real-world fire conditions.

The bundle wire and cable burning tester is a critical component of cable fire safety evaluation systems. Based on standards such as IEC, UL, GB/T, and EN, it assesses the flame-retardant and flame spread characteristics of bundled cables under controlled fire conditions. The test involves coordinated control of equipment configuration, sample preparation, ignition parameters, and data evaluation.

A thorough understanding of the test principles, applicable standards, and result interpretation methods is essential for ensuring accurate and reliable outcomes. Beyond certification purposes, bundle burning tests also play an important role in product design optimization and ongoing quality control in cable manufacturing.