Household and similar appliances:
IEC 60335-1 Ed.4
The fourth edition of the general
safety regulation for household and similar appliances
will shortly be published.
The most important modifications concern paragraph
29 (insulation distance) and paragraph 30 (fire
The new definitions laid down by the IEC 695-2-1
standard are indicated below.
GWFI - GLOW WIRE FLAMMABILITY INDEX
The highest temperature at which, in 3 consecutive
tests, the flame or glow of the test specimen
is extinguished within 30 seconds of the glow
wire being removed, without the underlying tissue
paper being set on fire by burning drops or particles
(in accordance with the IEC 695-2-1/2 standard).
GWIT - GLOW WIRE IGNITION TEMPERATURE
The temperature 25°C higher than the maximum
temperature of the glow wire at which no flame
develops in 3 consecutive tests (in accordance
with the IEC 695-2-1/3 standard); where the maximum
allowed flame development time is 5 seconds.
Plastic materials are combustible products with
variable effects on the speed of combustion according
to the extent of their intrinsic "self-extinguishing"
property (reduced combustibility) and as such
are considered potential fire sources.
For this reason, the manufacturers of household
appliances and consequently the reference standards
always tend to safeguard the market, and their
against the potential risk of fire, by raising
the design requirements of the plastic components
in terms of heat and fire resistance.
New modification proposals
Due to lack of space we shall focus our attention
on the recent modifications made to the standard,
which is about to be published, for unattended
devices, under the most critical fire risk
conditions (paragraph 30.2.3) for which the following
requirements are made:
- Parts made of an insulating material which
support electrical connections carrying a
current of over 0.2 A, including parts at
a distance of less than 3 mm, must have a
GWFI >= 850°C (IEC 60695-2-1/2).
- The part material must be classified with
GWIT >= 775°C for connections carrying
>0.2 A and GWIT >= 675°C for the
others, with the thickness of the reference
- If the material is not classified and the
GWT test is carried out in accordance with
the IEC 695.2.1/1 standard, the moulded parts
test temperature is 750°C for connections
that carry >0.2 A and 650°C for the
The part is considered suitable if no flame
develops during the test for more than 2 seconds.
If a flame develops for more than 2 seconds,
all the other parts above the electrical connection
lying within the area of a vertical cylinder
with a diameter of 20 mm and a height of 50
mm are to be subjected to the Needle-flame test
(annex E) unless they are "shielded"
by a material that has passed the Needle-test
(annex E). Parts made of materials classified
V0 or V1 in accordance with the IEC 60695-11-10
standard, with the same thickness, do not have
to be subjected to the Needle-flame test.
For fire risks and under the most critical conditions
considered (>0.2 A) the following conclusions
may be drawn:
- The supplier of a household or similar appliance
shall "guarantee" that the part
conforms to the IEC 60335-1 standard with
GWFI >= 850°C.
- The supplier of material for the parts mentioned
previously must "certify" that the
product conforms to the IEC 695-2-1/3 standard
with GWIT >= 775°C, for the thickness
of the part, where the maximum allowed flame
time during the test is 5 seconds.
- If the material has not been certified by
the supplier, the plastic part must be tested
at 750°C in accordance with the IEC 695-2-1/1
standard, taking 2 seconds as the maximum
flame time during the test, as mentioned above.
We await the complete publication of the aforesaid
standard to confirm the critical nature of these
new evaluation criteria which will certainly
limit the possibility of choosing between the
currently vast range of low combustibility products.
We believe that the new standards will not permit
the use of a large part of the so-called "Halogen
free" materials which seem today to
satisfy many "techno-eco-environmental"
requirements as well as marketing requirements.
LATI Industria Termoplastici S.p.A.
Via F. Baracca, 7 21040
Vedano Olona (VA) - Italy
Tel. : +390332409111 - Fax: +390332409307