Glow Wire Tester

Glow wire tester

Discussion of the Glow Wire Test (Varies as per relevant standard):

1. Object of the Test -

Components or parts under Fault or Overload conditions, may
attain a Temperature such that they will ignite parts in
their vicinity.

The GLOW - WIRE Test simulates thermal stresses which may be
produced by such source of heat or ignition. e.g. glowing
elements or overloaded resistors, may be for short duration,
in order to assess by a simulation technique the Fire Hazard.

2. General Description of the Test -

a. If possible, the specimen should be a complete
equipment, sub-assembly or a component.

b. While taking a part / parts of an enclosure for the
Tests, care must be taken to ensure that the Test
Conditions are not significantly different from those
occurring in the Normal usage, with regard to shape,
ventilation, effect of thermal stress and possible
flames occurring, burning or glowing particles falling
in the vicinity of the specimen.

c. The Test is applied to ensure -

1. That the Glow - wire Loop which is electrically
heated to a temperature specified, does not under
defined conditions cause ignition of the Part/Parts.

2. That the part which might have been ignited, has a
limited duration of burning, without spreading of
fire by its flame or burning or glowing particles.

d. This type of test may not be appropriate for too small
components / parts / sub assemblies, which may need
Needle Flame Test.


3. Test Apparatus -

a. The Glow - Wire consists of a specified loop of a Nickel
/ Chromium ( 80/20 ) wire of 4 mm dia.

b. Sheathed fine wire thermocouple, of overall dia. 0.5 mm
( wires of NiCr & NiAl ) with welded point / joint
located in the 0.6 mm hole in the Loop of Glow - Wire.

c. The Sheath consists of metal , resistant to a
temperature of 960 deg. C in working.

d. The instrument for measuring thermovoltage have 1 %
accuracy.

e. The Test Apparatus is so designed that the Glow - Wire
Loop is horizontal and the mounted specimen moves
horizontally towards the Loop with a force applied 0.8
to 1.2 N, for a penetration distance of 7 mm max.

f. To evaluate the possibility of spread of fire, a layer
of the material or components normally surrounded
underneath the specimen is placed underneath the
specimen at a distance equal to the distance between the
specimen and the surrounding material or components when
the specimen is mounted as in normal use.

If a subassembly or a part of the equipment is tested
separately, a piece of white pinewood board,
approximately 10 mm thick and covered with a single
layer of tissue paper, is positioned at a distance of
200+/- 5mm below the place where the glow-wire is
applied to the specimen, unless otherwise specified in the relevant specification.