AS/NZS 61241.1.2:2000

1 - AS/NZS 61241.1.2:2000 ELECTRICAL APPARATUS FOR USE IN THE PRESENCE OF COMBUSTIBLE DUST - ELECTRICAL APPARATUS PROTECTED BY....
4 - PREFACE
6 - CONTENTS
7 - INTRODUCTION
9 - 1 Scope
10 - 2 Normative references
11 - 3 Definitions
11 - 3.1 dust
11 - 3.2 combustible dust
11 - 3.3 conductive dust
11 - 3.4 explosive dust atmosphere
11 - 3.5 minimum ignition temperature of a dust layer
11 - 3.6 minimum ignition temperature of a dust cloud
11 - 3.7 dust ignition protection (DIP)
11 - 3.8 dust-tight enclosure
11 - 3.9 dust-protected enclosure
11 - 3.10 maximum surface temperature
11 - 3.11 maximum permissible surface temperature:
11 - 3.12 zones
12 - 3.13 zone 20
12 - 3.14 zone 21
12 - 3.15 zone 22
12 - 4 Area classification
13 - 5 Practices A and B
13 - 5.1 Practice A
13 - 5.2 Practice B
14 - 6 Selection according to temperature
14 - 6.1 Temperature limitation
14 - 6.1.1 Temperature limitations because of the presence of dust clouds
14 - 6.1.2 Temperature limitation because of presence of dust layers
16 - 6.2 Maximum permissible surface temperature
16 - 7 Selection of apparatus
16 - 7.1 Selection of practice A dust ignition protected apparatus
16 - 7.2 Selection of practice B dust ignition protected apparatus
16 - 7.3 Selection of radiating equipment
16 - 7.3.1 Ignition process
17 - 7.3.2 Safety measures in zone 20 or 21
17 - 7.3.3 Safety measures in zone 22
17 - 7.4 Selection of ultrasonic equipment
17 - 7.4.1 Ignition process
17 - 7.4.2 Safety measures
18 - 8 Installation
18 - 8.1 General
18 - 8.2 Access for inspection
18 - 8.3 Plans and records
18 - 8.4 Installation of apparatus
18 - 8.5 Integrity of insulation
19 - 8.6 Isolation
19 - 9 Wiring systems
19 - 9.1 Types of wiring
19 - 9.2 Static build-up
19 - 9.3 Dust collection
19 - 9.4 Cable and conduit entries
20 - 9.5 Accessories
20 - 9.6 Course of wiring
20 - 9.7 Thermal rating
20 - 9.8 Barriers
20 - 9.9 Flexible connection
20 - 9.10 Metal conduit systems
21 - 9.11 Plastic conduit systems
21 - 9.12 Conduit system joints
21 - 10 Inspection and maintenance
21 - 10.1 General
21 - 10.2 Qualifications of personnel
21 - 10.3 Isolation
21 - 10.4 Maintenance
22 - 10.5 Examination
23 - ANNEX A - Examples of dust layers of excessive thickness
24 - ANNEX B - Inspection, testing and maintenance
24 - B.1 General
24 - B.2 Documentation
24 - B.3 Inspections
24 - B.4 On site electrical testing
25 - B.5 Maintenance
26 - ANNEX C - General considerations
26 - C.1 Housekeeping
26 - C.2 Exclusion of electrical equipment from combustible dust areas
26 - C.3 Vibration
26 - C.4 Building design
27 - C.5 Hot surfaces
28 - ANNEX D - Inspection and maintenance checks
28 - D.1 Types of inspection
29 - D.2 Grades of inspection
29 - D.3 Inspection checks
31 - D.4 Maintenance
32 - D.5 Records
33 - ANNEX ZZ - Technical variations to IEC 61241-1-2:1999 for application in Australia and New Zealand
33 - ZZ.1 Introduction
33 - ZZ.2 Technical variations

Gives guidance on the selection, installation and maintenance of electrical apparatus for use in areas where combustible dusts are or may be present, in quantities which could lead to a fire or explosion hazard.

This part of AS/NZS 61241 gives guidance on the selection, installation and maintenance of 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.This Standard shall be read in conjunction with AS/NZS 2381.1, which describes the fundamental considerations which affect the selection, installation and maintenance requirements of all electrical equipment used in explosive atmospheres.NOTE AS/NZS 61241.1.1 specifies requirements for the design, construction and testing of electrical apparatus. Apparatus within the scope of this standard may also be subject to additional requirements in other standards for example, IEC 60079-0.The ignition protection is based on the limitation of the maximum surface temperature of the enclosure, and other surfaces which could be in contact with dust, and on the restriction of dust ingress into the enclosure by the use of dust-tight or dust-protected enclosures.The application of electrical apparatus in atmospheres which may contain explosive gas as well as combustible dust, whether simultaneously or separately, requires additional protective measures.Where the apparatus has to meet other environmental conditions, for example, protection against ingress of water and resistance to corrosion, additional methods of protection may be necessary. The method used is not to adversely affect the integrity of the enclosure.The principles of this standard may also be followed when combustible fibres or flyings cause a hazard.This standard does not apply to dusts of explosives which do not require atmospheric oxygen for combustion, or to pyrophoric substances.This standard is not applicable to electrical apparatus intended for use in underground parts of mines as well as those parts of surface installations of such mines endangered by firedamp and/or combustible dust. This standard does not take account of any risk due to an emission of flammable or toxic gas from the dust.This standard does not include other types of protection and is only applicable to protection by enclosures and surface temperature limitation.

First published as AS 2381.10-1989.
Second edition 1995.
Jointly revised and redesignated as AS/NZS 61241.1.2:2000.