IEC TS 60079-32-1:2013/AMD1:2017

IEC TS 60079-32-1 ®
Edition 1.0 2017-03
TECHNICAL
SPECIFICATION
SPECIFICATION
TECHNIQUE
A MENDMENT 1
AM ENDEMENT 1
Explosive atmospheres –
Part 32-1: Electrostatic hazards, guidance

Atmosphères explosives –
Partie 32-1: Dangers électrostatiques – Recommandations

IEC TS 60079-32-1:2013-08/AMD1:2017-03(en-fr)

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IEC TS 60079-32-1 ®
Edition 1.0 2017-03
TECHNICAL
SPECIFICATION
SPECIFICATION
TECHNIQUE
A MENDMENT 1
AM ENDEMENT 1
Explosive atmospheres –
Part 32-1: Electrostatic hazards, guidance

Atmosphères explosives –
Partie 32-1: Dangers électrostatiques – Recommandations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.260.20 ISBN 978-2-8322-8770-5

– 2 – IEC TS 60079-32-1:2013/AMD1:2017
© IEC 2017
FOREWORD
This amendment has been prepared by IEC technical committee 31: Equipment for explosive
atmospheres.
The text of this amendment is based on the following documents:
DTS Report on voting
31/1237/DTS 31/1253/RVC
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
_____________
2 Normative references
Replace the following two references:
IEC 60079-0, Explosive atmospheres – Part 0: Equipment – General requirements
IEC 60079-32-2, Explosive atmospheres – Part 32-2: Electrostatics hazards – Tests
with the following two new references:
IEC 60079-0:2011, Explosive atmospheres – Part 0: Equipment – General requirements
IEC 60079-32-2:2015, Explosive atmospheres – Part 32-2: Electrostatics hazards – Tests

© IEC 2017
Insert, after Clause 13, a new Clause 14 as follows:
14 Special requirements for equipment according to IEC 60079-0
14.1 General
In this document, threshold limits are given for electrostatic testing of products which differ
from the threshold limits in IEC 60079-0:2011. The threshold limits specified in this document
are in some cases more conservative, as they apply to a broad range of industrial applications
where the physical situation may be quite different to that in which electrical equipment
complying with IEC 60079-0 is used. The more conservative limits are based on theoretical
modeling supported by empirical data.
In order to have all relevant electrostatic requirements accessible in one place, the
requirements from IEC 60079-0:2011 are included for information in this clause of this
document, with the addition of helpful explanatory material and cross-references to other text
in this document.
The test methods in IEC 60079-32-2:2015 are equivalent to those cited in IEC 60079-0:2011,
but in some cases climatic conditions are different. Equipment within the scope of
IEC 60079-0 may be tested in the climatic conditions specified in IEC 60079-0.
NOTE The use in apparatus of products and materials conforming to the threshold limits specified in
IEC 60079-0:2011 is not known to have resulted in any accidental ignition.
14.2 Electrostatic charges on external non-metallic materials
14.2.1 Applicability
The requirements of this subclause only apply to external non-metallic materials of electrical
equipment, including non-metallic parts which are applied to the external surface of an
enclosure.
NOTE 1 Non-metallic paints, films, foils, and plates are typically attached to external surfaces of enclosures to
provide additional environmental protection. Their ability to store an electrostatic charge is addressed by this
subclause.
NOTE 2 It is generally acknowledged that glass is not susceptible to storing an electrostatic charge.
14.2.2 Avoidance of a build-up of electrostatic charge on Group I or Group II
electrical equipment
Electrical equipment should be so designed that under normal conditions of use, maintenance
and cleaning, danger of ignition due to electrostatic charges are avoided. This requirement
should be satisfied by one or more of the following:
a) By suitable selection of the material so that surface resistance shall meet at least one of
the criteria given below (see 6.2.1) when measured in accordance with IEC 60079-32-2:
– ≤ 100 GΩ measured at (30 ± 5) % relative humidity
– ≤ 1 GΩ measured at (50 ± 5) % relative humidity
NOTE 1 For more information see 6.1.
b) By limitation of the surface area of non-metallic parts of enclosures, determined according
to 6.3.2, to the values of Table 23.
The values for surface area can be increased by a factor of four if the exposed area of
non-metallic material is surrounded by and in contact with conductive earthed frames (see
6.3.3).
Alternatively, for long parts with non-metallic surfaces, such as tubes, bars, or ropes, the
surface area need not be considered, but the diameters or widths should not exceed the
values shown in Table 23.
– 4 – IEC TS 60079-32-1:2013/AMD1:2017
© IEC 2017
NOTE 2 Electric cables for connection of external circuits are not in the scope of Clause 14. Information on
external cables can be found in IEC 60079-14.
NOTE 3 Requirements for pipes and hoses for liquids are not in the scope of Clause 14. Requirements for
pipes and hoses for liquids are given in 7.7, and for solids in 9.3.3.
c) By provision of an insulating layer bonded to a conductive surface. This layer should meet
at least one of the following criteria:
1) the layer is not expected to be subject to high charging processes stronger than
manual rubbing (see 3.13) and has a thickness ≤ 2 mm for Groups I, IIA, IIB or
≤ 0,2 mm for Group IIC (see Table 23 and 6.3.4.2).
2) the breakdown voltage measured through the thickness of the insulating material is ≤ 4
kV (see 6.3.4.3) when measured as described in IEC 60079-32-2.
NOTE 4 According to IEC 60243-2, insulating materials stressed by DC have their breakdown voltage tested
with DC and the method described in IEC 60243-1 with the additional requirements in IEC 60243-2. This
method and the additional requirements are also given in IEC 60079-32-2.
d) By provision of a conductive coating (see 6.3.5). Non-metallic surfaces may be covered
with a bonded durable conductive coating. The resistance between the coating and either
the bonding point (in the case of fixed equipment) or the farthest point of possible contact
with the enclosure (in the case of portable equipment) should not exceed 1 GΩ. The
resistance should be measured in accordance with IEC 60079-32-2 but using the 100 mm
electrode at the worst case position of the surface and either the bonding point or the
farthest point of possible contact.
NOTE 5 The environmental conditions that have an effect on the coating material can include influences from
small particles in an air stream, solvent vapours, and the like.
e) By using any other safety measure in this Technical Specification to avoid the danger of
ignition due to electrostatic charges.
f) By testing that the maximum transferred charge measured according to IEC 60079-32-2
under worst case conditions is within the threshold limits of Table 23.
g) In specific cases, IEC 60079-0 allows the use of fixed equipment which does not fulfill the
requirements a) to f) and may have a risk from electrostatic discharges by marking them
with “X”. In this case, the instruction manual should provide guidance for the user to
minimize the risk from electrostatic discharges by operational measures. Where
practicable, the equipment should also be marked with the electrostatic charge warning
given in IEC 60079-0. However, this alternative should not be used if hazardous
electrostatic charging is expected during use (e.g. for hand-held equipment or for
constantly charging fixed installations).
NOTE 6 X-marking is used e.g. for insulating housings of electrical equipment that are touched by the
operator only during cleaning, maintenance and repair.

© IEC 2017
Table 23 – Alternative restrictions on insulating solid materials and isolated conductive
or dissipative parts in hazardous areas for equipment within the scope of IEC 60079-0
Group I Group II Group III
Sub EPL EPL EPL
EPL Ma, Mb EPL Ga EPL Gb EPL Gc
group Da Db Dc
2 2 2
A ≤5 000 mm ≤10 000 mm ≤10 000 mm
2 2 2 2
A) Surface area ≤10 000 mm B ≤2 500 mm ≤10 000 mm ≤10 000 mm No limits
2 2 2
C ≤ 400 mm ≤ 2 000 mm ≤ 2 000 mm

A ≤3 mm ≤30 mm ≤30 mm
B) Width of bars,
≤30 mm B ≤3 mm ≤30 mm ≤30 mm No limits
rods
C ≤1 mm ≤20 mm ≤20 mm
C) Thickness of A ≤2 mm
insulating
B ≤2 mm
coatings to avoid ≤2 mm No limits
brush
C ≤0,2 mm
discharges
Thickness of
insulating Not
≥ 8 mm
coatings to avoid Not permitted per Not permitted
if area > 500 mm
any incendive mitted
discharge
A ≤60 nC
No limits for
D) Transferred
insulating solids
≤60 nC B ≤25 nC
charge
a
≤200 nC
C ≤10 nC
A ≤3 pF ≤10 pF ≤10 pF
E) Capacitance
b
of unearthed ≤10 pF B ≤3 pF ≤10 pF ≤10 pF ≤10 pF
metal parts
C ≤3 pF
a
Value only valid for spark dis
...