A plastic enclosure, switch housing, or insulation component doesn't need to survive a bonfire to be considered fire-safe — it needs to survive the specific, low-energy ignition sources an internal fault could realistically produce. The IEC 60695 series of fire hazard tests is built around exactly that principle, and two of its most widely required test methods — glow wire and needle flame — exist because a resistive overheating fault and a small arcing flame are genuinely different ignition scenarios.
What Each Test Is Actually Simulating
Glow wire testing simulates the thermal effect of an overloaded resistor or poor connection that causes a component to glow hot without producing an actual flame — testing resistance to ignition by sustained contact heat.
Needle flame testing simulates a small flame from an arcing short circuit reaching nearby material — testing whether a material that does catch will self-extinguish rather than propagate fire further.
Many product safety standards require both tests, since a material can behave very differently under sustained contact heat versus brief flame exposure.
Glow Wire Testing — What Gets Measured
GWIT (Glow Wire Ignition Temperature), per IEC 60695-2-13, finds the lowest wire temperature at which the sample sustains combustion for five seconds or longer.
GWFI (Glow Wire Flammability Index), per IEC 60695-2-12, starts at a high temperature (commonly 960°C) and steps downward until the sample self-extinguishes within 30 seconds, without igniting a tissue paper layer beneath it.
GWEPT (Glow Wire End-Product Test), per IEC 60695-2-11, applies the same principle directly to a finished product rather than a flat material sample — generally the more representative test where practical.
Needle Flame Testing — What Gets Measured
IEC 60695-11-5 defines a premixed butane or propane flame of roughly 50W heat output, 12mm flame length, applied at 45 degrees for a duration the relevant product standard specifies — commonly 5 to 120 seconds. The key outcome is flame extinguishing time after the needle flame is withdrawn, and whether flaming drips ignite material beneath the sample.
Comparing the Two Test Methods
| Factor | Glow Wire Test | Needle Flame Test |
|---|---|---|
| Simulates | Sustained contact heat | Small flame (arc, short circuit) |
| Ignition source | Heated nickel-chromium wire (500–960°C) | Small gas flame (~12mm, ~50W) |
| Key measurements | GWIT, GWFI, or end-product pass/fail | Flame extinguishing time, flaming drip behaviour |
| Relevant standards | IEC 60695-2-10 through 2-13 | IEC 60695-11-5 |
Where These Tests Apply
Both test methods appear across household appliance plastics (IEC 60335-1), luminaire and LED driver housings (IEC 60598-1), switches and sockets (IEC 60884-1), IT/AV equipment, and automotive electronics. The product standard specifies which severity level applies to which component.
Practical Testing Notes
Test the actual material thickness used in the product, not an arbitrary standard sample — flammability performance is thickness-dependent. The LISUN ZRS-3H covers both glow wire and needle flame test requirements.