IEC 61241-1-1:1999

Electrical apparatus for use in the presence of combustible dust - Part 1-1: Electrical apparatus protected by enclosures and surface temperature limitation - Specification for apparatus

Is applicable to electrical apparatus protected by enclosures and surface temperature limitation for use in areas where combustible dust may be present in quantities which could lead to a fire or explosion hazard. It specifies requirements for design, construction and testing of electrical apparatus. Note - IEC 61241-2 gives guidance on the selection, installation and maintenance of the apparatus. Apparatus within the scope of this standard may also be subject to additional requirements in other standards - for example, IEC 60079-0.

Matériels électriques destinés ŕ ętre utilisés en présence de poussičres combustibles - Partie 1-1: Matériels électriques protégés par enveloppes et limitation de la température de surface - Spécification pour les matériels

Electrical apparatus for use in the presence of combustible dust - Part 1: Electrical apparatus protected by enclousures - Section 1: Specification for apparatus

General Information

• Status: Replaced
• Publication Date: 16-Jun-1999
• ICS: 29.260.20 - Electrical apparatus for explosive atmospheres
• Technical Committee: TC 31 - Equipment for explosive atmospheres
• Drafting Committee: MT 7 - TC 2/MT 7
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 07-Jul-2004
• Ref Project: SIST IEC 61241-1-1:1998 - Electrical apparatus for use in the presence of combustible dust - Part 1-1: Electrical apparatus protected by enclosures and surface temperature limitation - Specification for apparatus

Relations

• Replaced By: IEC 61241-1:2004 - Electrical apparatus for use in the presence of combustible dust - Part 1: Protection by enclosures "tD"
• Effective Date: 05-Sep-2023
• Replaced By: IEC 61241-0:2004 - Electrical apparatus for use in the presence of combustible dust - Part 0: General requirements
• Effective Date: 05-Sep-2023

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Electrical apparatus for use in the presence of combustible dust - Part 1: Electrical apparatus protected by enclousures - Section 1: Specification for apparatusElectrical apparatus for use in the presence of combustible dust - Part 1-1: Electrical apparatus protected by enclosures and surface temperature limitation - Specification for apparatus29.260.20Electrical apparatus for explosive atmospheresICS:Ta slovenski standard je istoveten z:IEC 61241-1-1 Ed. 2.0SIST IEC 61241-1-1:1998en01-april-1998SIST IEC 61241-1-1:1998SLOVENSKI
STANDA
...

INTERNATIONAL IEC
STANDARD
61241-1-1
Second edition
1999-06
Electrical apparatus for use in the presence
of combustible dust –
Part 1-1:
Electrical apparatus protected by
enclosures and surface temperature limitation –
Specification for apparatus
Matériels électriques destinés à être utilisés en présence
de poussières combustibles –
Partie 1-1:
Matériels électriques protégés par enveloppes et limitation
de la température de surface –
Spécification pour les matériels

Reference number
Numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series.
Consolidated publications
Consolidated versions of some IEC publications including amendments are

available. For example, edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the
base publication, the base publication incorporating amendment 1 and the base

publication incorporating amendments 1 and 2.

Validity of this publication
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology.
Information relating to the date of the reconfirmation of the publication is available
in the IEC catalogue.
Information on the subjects under consideration and work in progress undertaken
by the technical committee which has prepared this publication, as well as the list
of publications issued, is to be found at the following IEC sources:
• IEC web site*
•
Catalogue of IEC publications
Published yearly with regular updates
(On-line catalogue)*
• IEC Bulletin
Available both at the IEC web site* and as a printed periodical
Terminology, graphical and letter symbols
For general terminology, readers are referred to IEC 60050: International
Electrotechnical Vocabulary (IEV).
For graphical symbols, and letter symbols and signs approved by the IEC for
general use, readers are referred to publications IEC 60027: Letter symbols to be
used in electrical technology, IEC 60417: Graphical symbols for use on equipment.
Index, survey and compilation of the single sheets and IEC 60617: Graphical symbols
for diagrams.
* See web site address on title page.

INTERNATIONAL IEC
STANDARD
61241-1-1
Second edition
1999-06
Electrical apparatus for use in the presence
of combustible dust –
Part 1-1:
Electrical apparatus protected by
enclosures and surface temperature limitation –
Specification for apparatus
Matériels électriques destinés à être utilisés en présence
de poussières combustibles –
Partie 1-1:
Matériels électriques protégés par enveloppes et limitation
de la température de surface –
Spécification pour les matériels

 IEC 1999  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
V
International Electrotechnical Commission
For price, see current catalogue

– 2 – 61241-1-1 © IEC:1999(E)
CONTENTS
Page
FOREWORD . 3

INTRODUCTION .5

Clause
1 Scope . 6

2 Normative references . 6

3 Definitions. 7
4 Construction. 9
5 Enclosure materials. 10
6 Fasteners. 11
7 Interlocking devices. 11
8 Bushings. 11
9 Materials used for cementing. 12
10 Connection facilities and terminal compartments . 12
11 Connection facilities for earthing or bonding conductors. 12
12 Cable and conduit entries . 13
13 Supplementary requirements for electrical apparatus for practice B for use in zone 20 or 21. 14
14 Rotating electrical machines. 17
15 Switchgear . 18
16 Fuses. 19
17 Plugs and sockets . 19
18 Luminaries . 19
19 Caplights, caplamps and handlamps. 20
20 Verification and tests. 20
20.1 General. 20
20.2 Verification of documents . 21
20.3 Compliance of prototype or sample with documents. 21
20.4 Type tests . 22
20.4.1 General. 22
20.4.2 Mechanical tests . 22
20.4.3 Tests for dust exclusion by enclosures . 24

20.4.4 Torque test for bushings in enclosures for use in zone 20 or 21 . 25
20.4.5 Thermal tests . 26
20.4.6 Thermal shock test. 27
20.4.7 Tests of non-metallic enclosures or of non-metallic parts of enclosures
for use in zone 20 or 21. 27
21 Routine verifications and tests. 29
22 Manufacturer’s responsibility . 29
23 Verifications and tests on modified or repaired electrical apparatus. 29
24 Clamping tests of non-armoured and braided cables. 29
25 Clamping tests of armoured cables. 31
26 Marking. 32
27 Examples of marking. 34

61241-1-1 © IEC:1999(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
ELECTRICAL APPARATUS FOR USE IN THE

PRESENCE OF COMBUSTIBLE DUST –

Part 1-1: Electrical apparatus protected by enclosures and

surface temperature limitation – Specification for apparatus

FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61241-1-1 has been prepared by subcommittee 31H: Apparatus for
use in the presence of combustible dust, of IEC technical committee 31: Electrical apparatus
for explosive atmospheres.
This second edition cancels and replaces the first edition, published in 1993, and constitutes a
technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
31H/90/FDIS 31H/96/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
A bilingual version of this standard may be issued at a later date.

– 4 – 61241-1-1 © IEC:1999(E)
IEC 61241 consists of the following parts under the general title: Electrical apparatus for use in

the presence of combustible dust:

– Part 1: Electrical apparatus protected by enclosures and surface temperature limitation

– Part 2: Test methods
– Part 3: Classification of areas where combustible dusts are or may be present

1)
– Part 4: Type of protection pressurization "p"

1)
– Part 5: Intrinsically safe apparatus

________
1)
Under consideration.
61241-1-1 © IEC:1999(E) – 5 –
INTRODUCTION
Combustible dust can be ignited by electrical apparatus in several main ways:

• by surfaces of the apparatus that are above the minimum ignition temperature of the dust

concerned. The temperature at which a type of dust ignites is a function of the properties of

the dust, whether the dust is in a cloud or layer, the thickness of the layer and the geometry

of the heat source;
• by arcing or sparking of electrical parts such as switches, contacts, commutators, brushes,

or the like;
• by discharge of an accumulated electrostatic charge;
• by radiated energy (for example electromagnetic radiation);
• by mechanical sparking or frictional sparking or heating associated with the apparatus.
In order to avoid ignition hazards it is necessary that
• the temperature of surfaces, on which dust can be deposited, or which would be in contact
with a dust cloud, is kept below the temperature limitation specified in IEC 61241-1-2;
• any electrical sparking parts, or parts having a temperature above the minimum ignition
temperature of the dust
– are contained in an enclosure which adequately prevents the ingress of dust, or
– the energy of electrical circuits is limited so as to avoid arcs, sparks or temperatures
capable of igniting combustible dust;
• any other ignition sources are avoided.
The protection specified in this standard will not provide the required level of safety unless the
electrical apparatus is operated within its rating and is installed and maintained according to
the relevant codes of practice or requirements, for example in respect of protection against
over-currents, internal short circuits, and other electrical faults. In particular, it is essential that
the severity and duration of an internal or external fault be limited to values that can be
sustained by the electrical apparatus without damage.
Two different types of practice, A and B, are specified in this standard. Both are intended to
provide an equivalent level of protection.

– 6 – 61241-1-1 © IEC:1999(E)
ELECTRICAL APPARATUS FOR USE IN THE

PRESENCE OF COMBUSTIBLE DUST –

Part 1-1: Electrical apparatus protected by enclosures and

surface temperature limitation – Specification for apparatus

1 Scope
This part of IEC 61241 is applicable to electrical apparatus protected by enclosures and
surface temperature limitation for use in areas where combustible dust may be present in
quantities which could lead to a fire or explosion hazard. It specifies requirements for design,
construction and testing of electrical apparatus.
NOTE – IEC 6124
...