IEC 60079-1:2014/ISH1:2020

 IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
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IEC 60079-1
Edition 7.0  2014-06
EXPLOSIVE ATMOSPHERES –
Part 1: Equipment protection by flameproof enclosures "d"

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by IEC technical committee 31: Equipment for
explosive atmospheres.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
31/1536/DISH 31/1542/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.

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IEC 60079-1:2014 Edition 7.0, Explosive atmospheres – Part 1: Equipment protection by
flameproof enclosures "d"
Question 1:
The requirements given in 13.1 of IEC 60079-1:2014 (Edition 7) restrict threaded entries for
flameproof enclosures to only metric and NPT. Does this restriction represent a major
technical change between IEC 60079-1:2014 (Edition 7) and IEC 60079-1:2007 (Edition 6)?
Answer 1:
Yes, the restriction to only metric and NPT regarding threaded entries for flameproof
enclosures does represent a major technical change between IEC 60079-1:2014 (Edition 7)
and IEC 60079-1:2007 (Edition 6). The requirements given in Clause 13 of IEC 60079-1:2007
(Edition 6) had no such normative restriction, with reference to metric and NPT only as
examples of threaded entries for flameproof enclosures.
ICS 29.260.20
IEC 60079-1:2014-06/ISH1:2020-05(en)

– 2 – IEC 60079-1:2014/ISH1:2020
 IEC 2020
While IEC 60079-1:2014 (Edition 7) only permits the use of metric and NPT threads for entry
into flameproof enclosures, cable glands/conduit entry devices, thread adapters and blanking
elements are permitted to use other thread forms (see Annex C of IEC 60079-1:2014
(Edition 7)).
NOTE 1 The intention of the restriction to only metric and NPT regarding threaded entries for flameproof
enclosures is to minimize the mismatch of thread forms in enclosure entries.
NOTE 2 In the Foreword of IEC 60079-1:2014 (Edition 7), the table detailing the significance of the changes
between IEC 60079-1:2014 (Edition 7) and IEC 60079-1:2007 (Edition 6) mistakenly did not identify this metric and
NPT restriction as a major technical change. Unfortunately, the IEC Directives do not permit a corrigendum to be
issued to correct errors in non-normative text such as the table detailing the significance of changes.
Question 2:
Where a thread adapter is fitted and assessed as a factory-assembled part of the flameproof
enclosure, what are the permitted thread forms?
Answer 2:
A thread adapter may use thread forms other than metric and NPT, whether as an Ex
Equipment thread adapter or as a thread adapter fitted and assessed as a factory-assembled
part of the flameproof enclosure (see Annex C of IEC 60079-1:2014 (Edition 7)).
Question 3:
Can a blanking element be installed in a thread adapter which is fitted and assessed as a
factory-assembled part of the flameproof enclosure?
Answer 3:
Yes, the requirements given in Clause 13 of IEC 60079-1:2014 (Edition 7) regarding thread
adapters are for separately certified Ex equipment thread adapters, not those fitted and
assessed as a factory-assembled part of the flameproof enclosure.
Question 4:
What is the required marking when a thread adapter is fitted and assessed as a factory-
assembled part of the flameproof enclosure?
Answer 4:
Clause 13 of IEC 60079-1:2014 (Edition 7) requires identification of the specific thread type
and size of threaded entries into flameproof enclosures. In the case where the thread adapter
is fitted and assessed as a factory-assembled part of the flameproof enclosure, the
requirement for identification applies to the thread form of the adapter for the field wiring
connection.
 IEC 2020
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
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IEC 60079-1
Édition 7.0  2014-06
ATMOSPHÈRES EXPLOSIVES –
Partie 1: Protection du matériel par enveloppes antidéflagrantes "d"

FEUILLE D'INTERPRÉTATION 1
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