What is glow wire testing?

The Glow Wire Tester is a precision testing instrument specifically designed to detect and evaluate the potential fire hazards of various electrical and electronic products, household appliances, and related materials under high-temperature conditions.The equipment accurately simulates the thermal stress generated by overheated components inside electrical devices caused by fault currents, overload resistance, or other abnormal operating conditions. Through controlled testing, it determines whether materials or finished products are likely to ignite or sustain combustion when exposed to heat, thereby scientifically evaluating the fire safety performance and reliability of the products.This article will systematically introduce the Glow Wire Tester from multiple aspects, including its working principle, testing standards, operating procedures, and practical application cases. The aim is to help readers gain a more comprehensive and in-depth understanding of the functions and importance of this equipment, while also providing valuable reference information for safety production and quality control in related industries.

Core Functions of the Glow Wire Tester

The Glow Wire Tester is a specialized testing instrument used to evaluate the fire hazard risks of electrical and electronic products, household appliances, and related materials under high-temperature conditions. It is widely applied in research and development, quality inspection, and product certification processes.

Core Functions

Simulation of thermal hazard conditions

The tester uses a Φ4 mm U-shaped glow wire made of nickel-chromium alloy (Ni80/Cr20). The glow wire is heated to temperatures ranging from 300°C to 1000°C and then pressed vertically against the specimen with a force of 1.0 N (or 0.95 N) for 30 seconds.

This process simulates thermal stresses caused by:

Fault currents

Overloaded resistive components

Overheated electrical parts affecting nearby materials

Automatic recording of key parameters

The equipment automatically records important testing data, including:

Glow application time (Ta)

Ignition time (Ti)

Flame extinguishing time (Te)

Evaluation of material flame-retardant performance

The tester is used to determine important fire-resistance indices, including:

GWFI (Glow-Wire Flammability Index)

The highest temperature at which the material extinguishes within 30 seconds after removal of the glow wire without igniting the underlying tissue paper or bedding layer.

GWIT (Glow-Wire Ignition Temperature)

The highest temperature at which the material does not ignite under specified testing conditions.

Safety and visualization design

The system is equipped with:

Dark-background observation areas

Viewing windows

Exhaust and smoke extraction systems

It also supports:

Automatic specimen withdrawal

Data storage

Test report generation

These features improve testing safety, operational convenience, and result traceability.

Industries Applicable to the Glow Wire Tester

The Glow Wire Tester is widely used across multiple industries, particularly in fields where fire safety and flame-retardant performance are critical. Its main application industries include:

Electronics and Electrical Industry

Used for evaluating the flame-retardant performance and ignition risk of electronic components and complete products such as:

Switches

Sockets

Relays

Power adapters

Electronic assemblies

Home Appliance Industry

Applied to assess the fire resistance characteristics of plastic housings and internal insulating components in household appliances such as:

Refrigerators

Washing machines

Microwave ovens

Rice cookers

Other domestic electrical appliances

Lighting Equipment Industry

Used for safety testing of components including:

Lighting fixtures

Lamp holders

Ballasts

The tester evaluates performance under overload or fault conditions.

Low-Voltage Electrical Equipment Industry

Widely used for fire safety certification testing of products such as:

Circuit breakers

Contactors

Distribution boxes

Other low-voltage electrical devices

Material Research and Quality Inspection

Used to determine:

GWIT (Glow-Wire Ignition Temperature)

GWFI (Glow-Wire Flammability Index)

for plastics, insulating materials, and other non-metallic materials.

Third-Party Testing and Certification Laboratories

Serves as a standard testing instrument for product certification processes such as:

CCC certification

UL certification

CE certification

Automotive Interior and Industrial Equipment Industries

Some manufacturers use the tester to evaluate the flame-retardant properties of:

Automotive interior non-metallic components

Industrial control equipment

Electrical enclosure materials

The Glow Wire Tester plays an essential role in ensuring product safety, regulatory compliance, and fire hazard prevention across these industries.

Technical Features of the Glow Wire Tester

The Glow Wire Tester is a key testing instrument used to evaluate the fire hazard risks of electrical and electronic products, household appliances, and related materials under high-temperature conditions. It is widely applied in the research, development, and quality inspection of lighting products, low-voltage electrical equipment, insulating materials, and many other industries.

Core Technical Features

High-Precision Temperature Control

The temperature range is typically 0–1100°C, while some high-end models can reach 1050°C continuous testing capability.

The system commonly uses a K-type armored thermocouple (such as imported UK RS thermocouples) combined with PID algorithms or high-precision 16A/D ±0.05% temperature controllers.

Temperature control accuracy can reach ±2°C, exceeding the standard requirement of ±10°C.

Calibration is performed using the 960±15°C silver foil melting method, ensuring accurate and reliable temperature measurement.

Standardized Mechanical Structure

The glow wire is manufactured from Ni80/Cr20 nickel-chromium alloy with a diameter of Φ4 mm ±0.04 mm, bent into a U-shape or loop configuration.

A vertical contact force of 1.0 N ±0.1 N (or 0.95 N ±0.1 N for certain models) is applied to the specimen.

The specimen movement speed is generally within 10–25 mm/s, with common values of 13 mm/s or 16 mm/s.

The penetration depth is fixed at 7 mm, with support for preset adjustment functions.

Automation and Intelligent Control

Most systems adopt:

Microcontroller + touchscreen architecture

Or PLC + touchscreen control systems

The equipment supports one-button automatic testing and can automatically record key parameters such as:

Ignition time (Ti)

Flame extinguishing time (Te)

Glow application time (Ta)

Some models include built-in thermal printers for automatic report generation and printing.

Safety and Environmental Design

The combustion chamber volume is typically ≥0.5 m³.

The chamber interior uses a dark black background with illumination ≤20 Lux to facilitate flame observation.

Equipped with:

Exhaust ventilation systems

Smoke extraction and filtration devices

Optional smoke purification systems on some models

A standard bedding material is placed 200 mm ±5 mm below the specimen, typically consisting of pine wood board covered with 12–30 g/m² tissue paper, to evaluate ignition risk caused by flaming particles or dripping materials.

Operating Procedure of the Glow Wire Tester

Preparation Before Use

Environmental Requirements

The laboratory should maintain normal room temperature with a dry environment and no strong airflow to avoid interference with flame behavior or temperature stability.

The equipment should be placed on a stable and level workbench.

Power supply specifications are typically AC220V, 50Hz, and proper grounding must be ensured.

Equipment Inspection Items

Check the condition of the glow wire.

The glow wire is usually made of nickel-chromium alloy (Ni/Cr 80/20 or 77/20) with a standard diameter of Φ4 mm. During use, the actual diameter should remain above 3.9 mm. If contamination, oxidation, or excessive wear is found, the glow wire should be replaced immediately.

Verify that the K-type thermocouple (diameter Φ0.5–1.0 mm) is correctly connected.

The armored sheath should have a heat resistance capability of at least 1050°C.

Place the standard bedding material 200 mm ±5 mm below the specimen.

The bedding usually consists of a pine wood board covered with standard tissue paper weighing 12–30 g/m², used to evaluate whether the specimen ignites the underlying material.

Ensure the specimen fixture is firmly installed, with the specimen surface perpendicular to the glow wire and an initial gap of approximately 1 mm maintained.

Equipment Calibration (Recommended for First Use and Periodic Verification)

A commonly used calibration method is the pure silver foil calibration method:

Use silver foil with:

Purity: 99.8%

Thickness: 0.06 mm

Size: 2 mm × 2 mm

Place the silver foil on the tip of the glow wire and heat until the foil melts.

The theoretical melting temperature should be 960°C ±15°C.

Compare the measured temperature with the theoretical value to verify temperature control accuracy.

Operating Procedure

Power-On and Preheating Stage

Turn on the equipment power supply and activate the heating system.

Set the target temperature according to the testing standard, such as:

550°C

650°C

750°C

850°C

960°C

Wait until the temperature reaches the set value and stabilizes.

High-performance equipment typically requires 5–10 minutes for stabilization, with temperature fluctuation controlled within ±2°C.

Specimen Installation

Secure the pre-conditioned and dried specimen firmly onto the specimen holder.

Ensure the test surface is perpendicular to the glow wire.

Apply a constant contact force of:

1.0 N ±0.2 N

or 0.95 N ±0.1 N depending on the applicable standard.

Test Execution

Close the test chamber door and start the testing program through the control interface.

The system automatically drives the glow wire toward the specimen at a speed of 10–25 mm/s until contact is made.

Timing begins immediately after contact.

The standard glow application duration is typically:

30 seconds ±1 second

Adjustable within 10–60 seconds if required.

Data Recording and Observation

Key parameters are automatically or manually recorded, including:

Ignition Time (Ti) — the time at which visible flame first appears

Flame Extinguishing Time (Te)

Whether the bedding material (tissue paper or pine board) ignites

Some advanced models (such as KS-51B) include automatic judgment functions that directly output:

“Pass”

“Fail”

according to preset evaluation criteria.

Completion and Cleaning

After testing, the glow wire automatically retracts.

Activate the exhaust system to remove smoke.

After cooling, thoroughly clean all residues from the chamber.

Export and back up test data and generate standardized test reports if required.

Safety Precautions

Personal Protective Requirements

Operators must wear:

Heat-resistant gloves

Protective safety goggles

to prevent burns or flame splashes.

Equipment Safety

Never open the chamber door or move the equipment while it is operating at high temperature.

Keep power interfaces dry and avoid operating the equipment in high-humidity environments.

Emergency Measures

Fire extinguishing equipment should always be available near the testing area.

In case of abnormal conditions, immediately press the emergency stop button to cut off heating power and activate the safety protection system.

Importance of the Glow Wire Tester

The importance of the Glow Wire Tester is primarily reflected in its critical role in evaluating the fire hazards of electrical and electronic products, household appliances, and related materials. Its significance is demonstrated in the following aspects:

Ensuring Electrical Safety and Preventing Fire Risks

The Glow Wire Tester simulates high-temperature heat sources generated inside electrical equipment due to:

Overload conditions

Poor electrical contact

Fault currents

Overheated components

This allows evaluation of the ignition risk of materials or finished products under real operating conditions.

By determining important parameters such as:

GWIT (Glow-Wire Ignition Temperature)

GWFI (Glow-Wire Flammability Index)

the tester quantitatively evaluates the flame-retardant properties of materials and provides essential data support for product design and safety optimization.

Meeting International and National Mandatory Standards

The testing process complies with internationally recognized standards such as:

IEC 60695-2-10

GB/T 5169.10

UL 746A

These standards are mandatory or highly recommended requirements for products entering global markets including:

Europe

China

North America

The equipment is widely used in the research, development, and quality inspection of:

Lighting products

Low-voltage electrical equipment

Insulating materials

PCB substrate materials

Electronic assemblies

Improving Product Quality and Market Competitiveness

The tester helps identify material combustion behavior during the early stages of product development, enabling manufacturers to:

Optimize material selection

Improve structural design

Reduce product recall risks

It also provides repeatable and comparable testing data, enhancing customer confidence in product safety, which is especially important in industries such as:

Consumer electronics

Household appliances

Industrial control systems

Supporting Multi-Industry Applications and Standardized Testing

The Glow Wire Tester supports testing at multiple product levels, including:

Finished product testing (GWT)

Material testing (GWFI/GWIT)

This enables comprehensive fire safety evaluation throughout the entire product chain, from components to complete systems.

The equipment is typically equipped with:

Automatic temperature control (accuracy up to ±2°C)

High-precision timing systems (±0.1 s)

Dark-background observation windows

These features ensure high testing accuracy, consistency, and reliability.

In summary, the Glow Wire Tester is not only a core instrument for electrical fire safety testing, but also an essential tool for protecting consumer life and property while supporting product compliance and market entry worldwide.We sincerely welcome you to leave a message or contact us directly for more comprehensive product information, technical documentation, and professional support.