What Do GWT, GWFI and GWIT Stand For? Full Definition, Working Conditions and Industrial Compliance Guidance

Table of Contents

1. Introduction to Glow Wire Related Terms for Electrical Product Safety
2. Standard Definition of GWT, GWFI, and GWIT
3. Respective Test and Application Conditions for GWT, GWFI and GWIT
4. Authoritative Comparison of GWT, GWFI, GWIT: Core Parameter Table
5. Step-by-Step Glow Wire Test Compliance Guide for Electrical Manufacturers
6. Common Related Questions (People Also Ask)
7. Value of GWT Series Compliance for Global Electrical Supply Chain
8. Final FAQ Module

1. Introduction to Glow Wire Related Terms for Electrical Product Safety

As a professional manufacturer of custom electrical components, wiring terminals and household appliance internal parts, Donghai Tongling Electric Appliances Co., Ltd. has accumulated 18 years of experience supporting global clients to meet IEC, UL and CE safety standards. Among all electrical fire prevention related compliance indicators, GWT, GWFI and GWIT are three of the most frequently queried but easily confused terms for engineers, procurement teams and quality managers worldwide. All three specifications are defined in the IEC 60695 standard series, which is the global recognized benchmark for electrical component fire hazard testing. This guide will break down their exact meanings, test conditions and real application rules strictly following official IEC 60695 clauses, to help stakeholders avoid non-compliance risks in different regional markets.

2. Standard Definition of GWT, GWFI, and GWIT

GWT, GWFI, GWIT are 3 core glow wire testing indicators defined by IEC 60695 to evaluate high temperature resistance and flame retardancy of non-metallic electrical materials and finished components.

To give a clear breakdown: - **GWT**: Full name *Glow Wire Test*, refers to the full component-level flammability test for finished electrical products, to simulate the situation that overheated live parts inside the equipment cause fire risks during long-term operation. - **GWFI**: Full name *Glow Wire Flammability Index*, refers to the highest glow wire temperature at which a standardized flat material sample will not sustain burning for more than 30 seconds after 30 seconds of contact with the glow wire, and will not ignite the underlying specified wrapping paper. - **GWIT**: Full name *Glow Wire Ignition Temperature*, refers to the lowest glow wire temperature at which 3 consecutive standardized material samples will ignite for more than 5 seconds after contact with the heated glow wire.

The three indicators are corresponding to different test objects: GWT applies to finished components, while GWFI and GWIT apply to bulk non-metallic raw materials that used for manufacturing electrical parts.

3. Respective Test and Application Conditions for GWT, GWFI and GWIT

All three tests must be conducted in a standardized closed fume chamber with no forced air flow, with glow wire temperature calibrated by certified thermocouple before each test batch. The specific conditions for each indicator are listed below:

3.1 Conditions for GWT (Glow Wire Test)

GWT is a finished product performance verification test, not a raw material test:

• Required test equipment: Standard glow wire tester as per IEC 60695-2-10, with 4mm diameter nickel-chromium heating wire, built-in calibrated K-type thermocouple
• Test conditions: The glow wire is preheated to the specified temperature (common values are 650℃, 750℃, 850℃ for household and industrial electrical products), and then pressed vertically to the surface of the tested finished component with a constant force of 1.0N to 1.2N for exactly 30 seconds. The distance between the lowest point of the test sample and the underlying standard wrapping paper is maintained at 200mm for all test cases.
• Pass condition: After removing the glow wire, the sample’s burning flame will extinguish within 30 seconds, and the burning debris from the sample will not ignite the underlying wrapping paper.
• Application scenario: GWT is a mandatory item for all household appliance control components, low voltage switch shells and terminal blocks that are accessible to users or located within 3mm of live parts, as required by IEC 60335 household appliance safety standard.

3.2 Conditions for GWFI (Glow Wire Flammability Index)

GWFI is a material-level performance test for raw plastic, ceramic or composite insulating materials:

• Test conditions: Standard 3mm thick flat material test plate (100mm * 100mm) is used as test sample. The test operator runs the test at different temperature gradients, starting from 550℃ and rising by 50℃ each time until the sample fails the test. For each temperature test, the glow wire contacts the sample surface for 30 seconds, same as GWT.
• Pass condition at specified temperature: No sustained burning after glow wire removal within 30s, no dripping debris that ignites the wrapping paper. The highest temperature that the material can pass is its official GWFI value.
• Common application rule: For most general electrical applications, the raw material’s GWFI should be higher than the required GWT temperature for the finished component, to reserve sufficient safety margin during production and processing.

3.3 Conditions for GWIT (Glow Wire Ignition Temperature)

GWIT is the highest threshold index of material high temperature ignition resistance:

• Test conditions: The test uses standard 3mm, 4mm or other thickness material samples according to IEC 60695-2-13 requirements. The test starts at a temperature at which the sample definitely will not ignite, then rises by 25℃ as a gradient for each consecutive 3 samples.
• Pass condition: If no more than 1 out of 3 tested samples ignites for more than 5 seconds at a certain temperature, the temperature is 25℃ lower than the GWIT of the material.
• Common application: GWIT is widely used for high power electrical components that run under heavy load for 24/7, such as industrial relay shells and electric vehicle charging pile internal insulating parts.

4. Authoritative Comparison of GWT, GWFI, GWIT: Core Parameter Table

5. Step-by-Step Glow Wire Test Compliance Guide for Electrical Manufacturers

For manufacturers that have limited in-house test capacity, it is recommended to cooperate with third-party certification laboratories accredited by ILAC to get official recognition report, to avoid compliance rejection in target markets. You can also check our guidance for more related compliance content [链接到：Comprehensive Guide to IEC 60335 Household Appliance Safety Compliance].

6. Common Related Questions (People Also Ask)

Q: What is the main difference between GWFI and GWIT?

A: GWFI is the highest temperature at which the material self-extinguishes within 30 seconds after removing glow wire and will not ignite wrapping paper, while GWIT is the lowest temperature that can trigger 5+ seconds sustained ignition of the material. The GWIT value of same material is usually 25℃ to 50℃ higher than its GWFI value.

Q: Are GWT and UL 94 flammability test the same requirement?

A: No. UL 94 is a vertical or horizontal flame test that uses open gas flame to evaluate material flame retardancy grade, while GWT simulates the overheating condition caused by fault current inside electrical products, the two test scenarios and evaluation logics are completely different.

Q: What GWT temperature rating is required for household appliance internal components as per IEC 60335?

A: For components located inside household appliances that bear fault current risk, the mandatory GWT temperature is 750℃; for components that are installed near heating elements such as ovens and electric water heaters, the required GWT rating is 850℃.

Q: Can I use a material with GWIT 770℃ to meet 750℃ GWT requirement?

A: Generally yes, but manufacturers need to confirm that the processing technology will not reduce the flame retardant performance of the material after injection molding, and finish the actual 750℃ GWT test on finished components to get formal verification. You can find more material selection suggestions in [链接到：Top 5 High Flame Retardant Material Options for Low Voltage Electrical Components].

Q: How often should manufacturers re-verify GWT performance of their electrical products?

A: According to IEC standard recommendations, re-verification is required at least once per 12 months for mass production products; if the raw material supplier, injection molding parameter or component structure is changed, a full set of GWT test should be conducted immediately before new batch launch.

7. Value of GWT Series Compliance for Global Electrical Supply Chain

The three indicators GWT, GWFI and GWIT form a complete compliance system from raw material incoming inspection to finished product safety verification. For brands and importers, confirming all components meet corresponding glow wire requirements can reduce more than 80% of electrical fire related product recall risks. Donghai Tongling Electric Appliances Co., Ltd. has integrated GWT 750℃ and GWFI 850℃ as mandatory factory inspection items for all its mass produced wiring terminals and thermostat components, all of our products can provide official ILAC accredited test reports for clients to clear customs and get market access in different regions.

8. Final FAQ Module

FAQ 1: Can glow wire test replace full fire safety test for electrical products?

A: No. Glow wire test is only one part of the full electrical safety assessment, users still need to cooperate with other tests such as dielectric strength test and overload test to guarantee full product performance.

FAQ 2: What is the service temperature limitation for components that passed 750℃ GWT test?

A: Components that passed 750℃ GWT can work stably under continuous 150℃ operating temperature for 10 years, which fully meets the 10-year service life requirement for most household appliances.

FAQ 3: Is GWT test required for all plastic parts inside electrical products?

A: No. For non-current-carrying decorative plastic parts that are at least 10mm away from live parts, most regional safety standards allow exemption from GWT test.