When you review the technical documentation for a CE-marked LED luminaire, you’ll typically find a reference to glow wire testing tucked between insulation resistance values and IP class verification. Many buyers treat it as a box-tick buried in the test report. In reality, the glow wire test is one of the most directly relevant fire safety evaluations an industrial LED product can undergo — and understanding what it tests, why different temperature thresholds exist, and how it connects to the standards that govern your market, gives you a meaningful edge in evaluating whether a fixture is genuinely safe for its intended environment.
Key Takeaways
- The glow wire test simulates internal electrical fault conditions — overheated connections, overloaded components — to verify that plastic parts in a luminaire will not ignite and propagate fire.
- It is a mandatory requirement within IEC 60598-1 (the general luminaire safety standard), with test temperatures ranging from 550°C to 960°C depending on application and component risk level.
- Emergency luminaires (IEC 60598-2-22) face heightened glow wire requirements — 850°C is the benchmark for materials on escape route lighting — because these fixtures must remain functional precisely when electrical faults are most likely to be present.
- Two material-level indices matter to specification engineers: GWFI (Glow Wire Flammability Index) and GWIT (Glow Wire Ignition Temperature). Understanding both is essential when reviewing material compliance data from LED manufacturers.
What the Glow Wire Test Is Actually Testing
The Fault Scenario It Simulates
Most electrical fires in luminaires and control equipment do not start from open flames. They originate from overloaded components, poorly terminated connections, or failing contacts that generate sustained, intense local heat — a glowing, non-flaming thermal source. This is precisely what the glow wire test is designed to replicate. A nickel-chromium (Ni/Cr) resistance wire, standardized in material and geometry under IEC 60695-2-10, is heated electrically to a prescribed temperature and pressed against the test specimen with a defined 1.0 N force for 30 seconds. The test observes whether the material ignites, how long any flame persists, and critically — whether flaming drips fall and ignite a tissue paper indicator placed 200 mm below the specimen.
Pass criteria are unambiguous: any flame or glowing must extinguish within 30 seconds of the glow wire being removed, and the tissue paper below must not ignite. These criteria are defined in the IEC 60695-2 series and then referenced by end-product standards — most relevantly for lighting, IEC 60598-1 (general luminaires) and IEC 60598-2-22 (emergency luminaires). Compliance with these standards is a prerequisite for CE marking under the EU Low Voltage Directive.
Why Temperature Thresholds Differ
The glow wire test is severity-graded. The test temperature is not fixed — it is determined by the application environment, the current level carried by the component, and whether the equipment operates attended or unattended. Under the luminaire requirements derived from IEC 60598, the following framework applies to different component classes within a fixture:
- 550°C — Non-current-carrying parts where the fire risk from a thermal fault is lowest
- 650°C — Standard operating equipment; this is the baseline glow wire test temperature specified in IEC 60598-1 for most general luminaire parts subjected to test using the nickel-chromium wire
- 750°C — Parts in harsh conditions or supporting current-carrying components with fixed accessories
- 850°C — Equipment operating unattended under continuous load; the key threshold for emergency lighting and for French national requirements under EN IEC 60598-1 for luminaires in stairwells and horizontal escape paths
- 960°C — The most severe rating: unattended continuous load in harsh environments near building supply points
The implication for procurement is direct: a fixture marketed for use in food processing facilities, cold chain warehouses, or emergency escape routes should be evaluated against 850°C compliance data for its plastic housings and driver enclosures — not just the 650°C baseline. A product that passes at 650°C but not 850°C presents a meaningful fire safety gap when deployed in high-risk or unattended continuous-operation environments.
GWFI and GWIT: The Two Indices That Appear on Material Datasheets
What GWFI Means
The Glow Wire Flammability Index (GWFI), defined in IEC 60695-2-12, is determined by testing a flat sample of raw material (not the finished product). It is reported as the highest temperature at which the material does not sustain ignition — meaning any flame self-extinguishes within 30 seconds of glow wire removal and no flaming drips ignite the tissue below. A material datasheet might list “GWFI 850/3.0” — indicating a 3.0 mm thick specimen passed at 850°C. This index is used during the product design phase to screen and pre-qualify plastic materials before end-product testing. A higher GWFI indicates a material that resists fire propagation from thermal fault conditions across a wider temperature range.
What GWIT Means
The Glow Wire Ignition Temperature (GWIT), defined in IEC 60695-2-13, is a more conservative and demanding index. It identifies the temperature at which a material actually ignites — defined as flames persisting for more than 5 seconds during the application. GWIT is reported as the temperature 25°C above the maximum test temperature that did not produce such ignition across three consecutive specimens. For most applications requiring IEC 60335-1 compliance (household appliances with current-carrying parts), a GWIT of 775°C or higher is required. In practice, many materials that pass UL 94 V-0 flame classification still fail the GWIT requirement, because the 5-second ignition threshold in GWIT is more demanding than UL 94’s vertical burn criteria.
Why Material-Level Data Alone Is Not Sufficient
A critical distinction that experienced procurement engineers understand: a component’s GWFI and GWIT values from raw material testing do not automatically predict whether the finished part will pass the end-product glow wire test (GWEPT per IEC 60695-2-11). End-product geometry affects heat distribution, wall thickness, and contact area with the glow wire differently than flat test plaques. This is why reputable manufacturers conduct end-product testing on actual luminaire assemblies — not just material-level datasheet claims. When reviewing compliance documentation, the relevant question is whether glow wire testing was performed on the actual end product or only on raw material samples.
Glow Wire Testing and LED Luminaire Design
Which Parts of an LED Fixture Are Tested
Not every component in a luminaire requires glow wire evaluation — the standard focuses on parts that could be affected by a thermal fault originating from the electrical system. In an industrial LED weatherproof fixture, the primary test candidates are: the LED driver housing (which operates continuously and encloses the electrical supply components); terminal blocks and wiring supports within the housing; any plastic diffusers or lenses in proximity to the driver compartment; and cable entry components or gland housings. In an emergency luminaire, the battery management housing and the battery compartment enclosure are also subject to elevated glow wire requirements because the battery system itself can generate significant heat under fault conditions, precisely in an emergency scenario when overloads are most likely.
The Emergency Lighting Special Case
Emergency luminaires present a compound fire safety challenge: they must remain operational in the event of a fault that — by definition — may involve overheated electrical components elsewhere in the building. IEC 60598-2-22, the international standard governing emergency luminaires, specifies glow wire requirements in coordination with IEC 60598-1. Beyond the base standard, the French national variant of EN IEC 60598-1 mandates 850°C glow wire testing for luminaires installed on stairwells and horizontal escape routes — a requirement widely adopted as best practice by the ICEL (Industry Committee for Emergency Lighting) certification scheme, which is recognized across the UK, Ireland, and parts of Europe. Specifying emergency fixtures for EU or UK projects without confirming 850°C compliance for the plastic enclosure components represents a measurable and avoidable compliance gap.
How Glow Wire Compliance Connects to CE Marking and Product Certification
The Pathway from Test to Certificate
CE marking for a luminaire under the EU Low Voltage Directive (LVD) requires demonstration of conformity with applicable harmonized standards — the primary one being EN IEC 60598-1. Glow wire testing is one of the test clauses within that standard that must be satisfied. A manufacturer can self-declare CE conformity (assembling a technical construction file with test evidence) or have the product tested by a third-party accredited laboratory. In either case, the glow wire test results — the specific temperature applied, the component tested, and the pass/fail outcome — must be documented in the technical file. For industrial-grade weatherproof or emergency fixtures sold into the EU, UK (where UKCA marking applies post-Brexit), or Australia (where SAA approval under AS/NZS standards is required), glow wire compliance documentation is a component of the product safety evidence reviewed during market surveillance or distribution vetting.
ENEC: The More Rigorous Third-Party Route
For buyers whose procurement specifications require third-party certified luminaires rather than self-declared CE marks, ENEC certification (European Norm Electrical Certification) provides a higher assurance level. ENEC is issued by a network of accredited certification bodies across Europe — including TÜV, KEMA, DEKRA, and others — following factory inspection and product testing against EN IEC 60598. The glow wire test is among the test items verified as part of ENEC certification, and ENEC-certified products carry a visible mark that procurement teams can verify against the ENEC database without needing to independently validate the underlying test reports. For large commercial or infrastructure projects where safety liability is a significant consideration, ENEC-certified luminaires provide a straightforward answer to compliance due diligence.
Glow Wire Testing in the Context of Industrial and Emergency LED Procurement
Industrial facilities operating continuous-duty lighting — cold storage, food processing, warehousing — run their luminaires unattended for thousands of hours per year. The electrical connections, driver circuitry, and terminal blocks inside weatherproof fixtures operate at elevated temperatures over their service life. The glow wire test is the mechanism by which a buyer can verify, in advance of installation, that a thermal fault in that driver compartment will not propagate to a sustained fire. Paying attention to whether a weatherproof fixture was tested at 650°C or 850°C — and whether testing was done on raw material samples or actual end-product assemblies — is the kind of specification discipline that separates defensible procurement from checkbox compliance.
Cold storage facilities with tight IP requirements add another layer: the combination of sealed enclosures (IP65 or IP66) and continuous operation means that any heat generated inside the fixture has limited pathways for dissipation. This makes the material quality of the driver housing and internal supports more — not less — important in cold chain environments than in ventilated industrial spaces. Specifying weatherproof fixtures where the driver housing plastic has a confirmed GWFI of 850°C and GWIT of 775°C or above, tested under IEC 60598-1 conditions, provides a meaningful safety margin in exactly this context.
Fanxstar’s weatherproof LED fixtures and emergency lighting range are designed and tested with these requirements in mind. For project specifications requiring glow wire compliance documentation, test temperature levels applied, or material GWFI/GWIT data for specific product models, our engineering team provides detailed technical documentation as part of the pre-sales process. Contact us with your application details to receive specific compliance evidence for your project — or explore our emergency lighting range and weatherproof LED fixtures to see the product lines where these standards apply directly.
Frequently Asked Questions
Is the glow wire test the same as a UL 94 flammability test?
No — they test different things and are not interchangeable. UL 94 classifies plastic materials by their burning behavior when a flame is applied to them, using a vertical or horizontal burn methodology. The glow wire test simulates a glowing heat source (a faulty electrical component), not an open flame. Many materials that achieve UL 94 V-0 ratings still fail the GWIT requirements under IEC 60695-2-13 because the ignitability threshold in glow wire testing is applied differently. Both tests provide complementary fire safety information; the glow wire test is more directly relevant to the fault conditions that occur inside electrical luminaires.
What glow wire temperature should I specify for a cold storage LED fixture?
For a weatherproof LED fixture operating unattended on continuous load — which describes the vast majority of cold chain and industrial warehouse installations — the relevant driver housing material should demonstrate compliance at 850°C per IEC 60598 requirements for equipment in that usage class. The 650°C baseline that applies to general-purpose luminaires is not a sufficient specification for continuous-duty unattended industrial applications. When requesting compliance documentation from a manufacturer, ask specifically for the test temperature applied during glow wire testing, the component tested, and whether testing was conducted on the end product or on raw material samples.
Does CE marking guarantee glow wire compliance?
CE marking indicates that a manufacturer has declared conformity with applicable EU directives and harmonized standards — including the glow wire clauses in EN IEC 60598-1. However, CE is a self-declaration that can be made without third-party testing, and the underlying technical file is not routinely inspected unless a market surveillance authority investigates a specific product. For procurement purposes, confirming glow wire compliance means requesting the actual test report or — for higher confidence — specifying ENEC-certified products where the glow wire test was independently verified by an accredited certification body.
What is the glow wire test for emergency luminaires specifically?
Emergency luminaires are governed by IEC 60598-2-22, which applies glow wire requirements in conjunction with the general requirements of IEC 60598-1. The baseline requirement for enclosure materials in emergency luminaires is that they pass glow wire testing at 850°C under IEC 60695-2-11 end-product conditions. This elevated threshold — relative to the 650°C baseline for general luminaires — reflects the specific safety logic: emergency lights must function during and immediately after the kind of electrical fault events that glow wire testing is designed to simulate. In certain jurisdictions (notably France) and under ICEL certification schemes applicable in the UK and Ireland, 850°C compliance is either mandatory or considered best practice for luminaires on escape routes and in stairwells.
How is GWFI different from GWIT, and which is more important?
GWFI (Glow Wire Flammability Index) measures a material’s ability to resist fire propagation — specifically, whether it self-extinguishes within 30 seconds and produces no igniting drips. GWIT (Glow Wire Ignition Temperature) measures the temperature threshold at which a material ignites and sustains combustion for more than 5 seconds. GWIT is the more demanding of the two: it is typically reported as 25°C higher than the highest test temperature that produced no sustained ignition, and many materials that have acceptable GWFI values fail to achieve adequate GWIT because the 5-second flame duration criterion is strict. For specification engineers, GWFI is more commonly listed in manufacturer datasheets and used for material pre-selection; GWIT is the relevant index when compliance with standards like IEC 60335-1 (household appliances) requires a minimum 775°C ignitability threshold.
