IEC 60079-11:2006

Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i"

Specifies the construction and testing of intrinsically safe apparatus intended for use in an explosive gas atmosphere and for associated apparatus, which is intended for connection to intrinsically safe circuits which enter such atmospheres. The contents of the corrigendum of December 2006 and interpretation sheet 1 of December 2019 have been included in this copy.

Atmosphères explosives - Partie 11: Protection de l'équipement par sécurité intrinsèque «i»

Spécifie la construction et les essais pour le matériel électrique de sécurité intrinsèque destiné à être utilisé dans les atmosphères explosives et pour le matériel électrique associé, qui est destiné à être relié à des circuits de sécurité intrinsèque qui entrent dans de telles atmosphères. Le contenu du corrigendum de décembre 2006 et la feuille d'interprétation 1 de décembre 2019 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 24-Jul-2006
• ICS: 29.260.20 - Electrical apparatus for explosive atmospheres
• Technical Committee: SC 31G - Intrinsically-safe apparatus
• Drafting Committee: MT 60079-11 - TC 31/SC 31G/MT 60079-11
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 30-Jun-2011

Relations

• Corrected By: IEC 60079-11:2006/COR1:2006 - Corrigendum 1 - Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i"
• Effective Date: 05-Sep-2023
• Revises: IEC 60079-11:1999 - Electrical apparatus for explosive gas atmospheres - Part 11: Intrinsic safety "i"
• Effective Date: 05-Sep-2023
• Revised: IEC 60079-11:2011 - Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i"
• Effective Date: 05-Sep-2023
• Revised: IEC 60079-11:2006/ISH1:2019 - Interpretation sheet 1 - Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i"
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60079-11
Edition 5.0 2006-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 11: Equipment protection by intrinsic safety "i"

Atmosphères explosives –
Partie 11: Protection de l’équipement par sécurité intrinsèque «i»

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IEC 60079-11
Edition 5.0 2006-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 11: Equipment protection by intrinsic safety "i"

Atmosphères explosives –
Partie 11: Protection de l’équipement par sécurité intrinsèque «i»

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XE
CODE PRIX
ICS 29.260.20 ISBN 2-8318-8749-6

 IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
IEC 60079-11
Edition 5.0  2006-07
EXPLOSIVE ATMOSPHERES –
Part 11: Equipment protection by intrinsic safety "i"

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by subcommittee 31G: Intrinsically-safe
apparatus, of IEC technical committee 31: Equipment for explosive atmospheres.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
31G/310/DISH 31G/313/RVDISH
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.
___________
Background
The maximum surface temperature shall be determined as follows:
All current-limiting devices external to the cell or battery shall be short-circuited for the test.

Any external sheath (of paper or metal, etc.) not forming part of the actual cell enclosure shall
be removed for the test. The temperature shall be determined on the outer enclosure of each
cell or battery and the maximum figure taken. The test shall be carried out both with internal
current-limiting devices in circuit and with the devices short-circuited using 10 cells in each
case. The 10 samples having the internal current-limiting devices short-circuited shall be
obtained from the cell/battery manufacturer together with any special instructions or
precautions necessary for safe use and testing of the samples.
The intent of the cited paragraphs is to simulate an internal short inside a cell, by shorting the
cell’s external terminals for the purpose of thermal assessment.
It was found that two details have been misinterpreted in this subclause:
a) The subjects of this subclause are cells or batteries, while the intent is clearly to
simulate internal shorts inside cells and not inside batteries in which case the shorts
could be interpreted as being external to the cell(s) within a battery.
ICS 29.260.20
– 2 – IEC 60079-11:2006/ISH1:2019

 IEC 2019
b) It is unclear what constitutes a current limiting device that protects against internal

shorts.
A separator with shutdown function may be interpreted as a current limiting device that

protects against internal shorts by its function, but since it is a constructional part of the cell

that is not removable without invalidating the functionality of the basic cell, it is not a current
limiting device for the purposes of implementing the standard. Conversely, a CID (Current

interruption device), for example, is a switch that is triggered by increased pressure inside the

cell, and the cell’s functionality is not invalidated by the absence of the CID.

The reference to internal current limiting devices that protect against internal shorts in edition

6 was included to address unknown future cell technologies which could include such current

limiting devices, however at this time no such current limiting devices are known.
Question
For either Level of Protection “ia” or “ib”, what are the current limiting devices that are
required to be disabled (or equivalent e.g. not fitted, short-circuited or removed) by IEC
60079-11:2006, Subclause 10.5.3 b), and what are the current limiting devices that need not
be disabled?
Answer
All discrete protective devices that can be schematically represented as individual devices
apart from the cell are to be disabled for the purposes of testing according to IEC 60079-
11:2006, Subclause 10.5.3 b), regardless if they are located inside the cell or if they are
external to the cell. This includes, but is not limited to resistors, fuses, resettable fuses (NTC,
PTC, PPTC), CID (current interruption device), semiconductors, etc.
Features that provide essential cell functions, such as a separator with shutdown function or
the ohmic resistance of the electrolyte, are not considered current limiting devices in the
sense of this clause and need not be shorted or removed, and such cells can be considered
for Level of Protection “ia”.
60079-11  IEC:2006 – – 2 –3 – 60079-11 © IEC:2006
CONTENTS
FOREWORD.6

Scope.8
2 Normative references.10
3 Terms and definitions .11
4 Grouping and classification of intrinsically safe apparatus and associated apparatus .16
5 Levels of protection and ignition compliance requirements of electrical apparatus.16
5.1 General .16
5.2 Level of protection "ia" .16
5.3 Level of protection "ib" .17
5.4 Level of protection "ic" .17
5.5 Spark ignition compliance .18
5.6 Thermal ignition compliance .18
5.7 Simple apparatus.22
6 Apparatus construction .22
6.1 Enclosures .23
6.2 Facilities for connection of external circuits .23
6.3 Separation distances .27
6.4 Protection against polarity reversal .38
6.5 Earth conductors, connections and terminals .38
6.6 Encapsulation.40
7 Components on which intrinsic safety depends.40
7.1 Rating of components .40
7.2 Connectors for internal connections, plug-in cards and components .41
7.3 Fuses .41
7.4 Primary and secondary cells and batteries .42
7.5 Semiconductors.46
7.6 Failure of components, connections and separations.47
7.7 Piezo-electric devices .48
7.8 Electrochemical cells for the detection of gases .48
8 Infallible components, infallible assemblies of components and infallible
connections on which intrinsic safety depends.48
8.1 Mains transformers.48
8.2 Transformers other than mains transformers.50
8.3 Infallible windings .5 1
8.4 Current-limiting resistors.52
8.5 Blocking capacitors.52
8.6 Shunt safety assemblies .53
8.7 Wiring, printed circuit board tracks, and connections. .54
8.8 Galvanically separating components .56

60079-11 © IEC:200660079-11  IEC:2006 – – 3 –5 –
9 Diode safety barriers.57
9.1 General . 57
9.2 Construction .57
10 Type verifications and type tests .57
10.1 Spark ignition test.
...