Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is drafted in accordance with the rules given in the GB/T 1.1-2020 Directives for Standardization — Part 1: Rules for the Structure and Drafting of Standardizing Documents.
This part is Part 8 of GB/T 3836 Explosive Atmospheres. The following parts of GB/T 3836 have been published:
— Part 1: Equipment — General Requirements;
— Part 2: Equipment Protection by Flameproof Enclosures “d”;
— Part 3: Equipment Protection by Increased Safety “e”;
— Part 4: Equipment Protection by Intrinsic Safety "i";
— Part 5: Equipment Protection by Pressurized Enclosure “p”;
— Part 6: Equipment Protection by Oil Immersion “o”;
— Part 7: Equipment Protection by Powder Filling “q”;
— Part 8: Equipment Protection by Type of Protection “n”;
— Part 9: Equipment Protection by Type of Protection “m”;
— Part 11: Material Characteristics for Gas and Vapour Classification — Test Methods and Data;
— Part 12: Material Characteristics for Combustible Dusts — Test Methods;
— Part 13: Equipment Repair, Overhaul and Reclamation;
— Part 14: Classification of Areas — Explosive Gas Atmosphere;
— Part 15: Electrical Installations Design, Selection and Erection;
— Part 16: Electrical Installations Inspection and Maintenance;
— Part 17: Equipment Protection by Pressurized Room “p” and Artificially Ventilated Room “v”;
— Part 18: Intrinsically Safe Electrical Systems;
— Part 20: Equipment with Equipment Protection Level (EPL) Ga;
— Part 21: Application of Quality Systems for Equipment Manufacture;
— Part 22: Protection of Equipment and Transmission System using Optical Radiation;
— Part 23: Group I, Category EPL Ma Equipment Intended to Remain Functional in Atmospheres Endangered by Firedamp and/or Coal Dust
— Part 24: Equipment Protection by Special Protection “s”;
— Part 25: Requirements for Process Sealing between Flammable Process Fluids and Electrical Systems;
— Part 26: Electrostatic Hazards — Guidance;
— Part 27: Electrostatic Hazards — Test;
— Part 28: Non-electrical Equipment for Potentially Explosive Atmospheres — Basic Method and Requirements;
— Part 29: Non-electrical Equipment for Explosive Atmospheres — Constructional Safety “c”, Control of Ignition Source “b”, Liquid Immersion “k;
— Part 30: Equipment and Components in Explosive Atmospheres in Underground Mines;
— Part 31: Equipment Dust Ignition Protection by Enclosure “t”;
— Part 32: Intrinsically Safe Systems with Electronically Controlled Spark Duration Limitation;
— Part 33: Equipment in Adverse Service Conditions;
— Part 34: Equipment Assemblies;
— Part 35: Classification of Areas for Explosive Dust Atmospheres;
This standard replaces GB 3836.8-2014 Explosive Atmospheres — Part 8: Equipment Protection by Type of Protection “n” in whole, and the following technical deviations have been made with respect to the GB 3836.8-2014:
— The range of internal working voltage is modified (see Clause 1; Clause 1 of Edition 2014);
— The non-sparking device “nA” is deleted and transferred to GB/T 3836.3, "ec” (see Clause 3 of Edition 2014);
— The enclosed-break device “nC” is deleted and transferred to GB/T 3836.2, "dc” (see Clause 3 of Edition 2014);
— The term and definition of hermetically-sealed device “nC” is modified (see Clause 3; Clause 3 of Edition 2014);
— The term and definition of normally sparking device is added (see Clause 3);
— The provisions of small components are deleted (see 5.2 of Edition 2014);
— The requirements for connection facilities and terminal compartments are deleted (see Clause 7 of Edition 2014);
— The supplementary requirements for non-sparking electrical rotating machines are deleted (see Clause 8 of Edition 2014);
— The supplementary requirements for non-sparking fuses and fuse assemblies are deleted for instrumentation (see Clause 9 of 2014 Edition);
— The supplementary requirements for non-sparking plugs and sockets are deleted (see Clause 10 of Edition 2014);
— The supplementary requirements for non-sparking luminaires are deleted (see Clause 11 of Edition 2014);
— The supplementary requirements for equipment incorporating non-sparking cells and batteries are deleted (see Clause 12 of Edition 2014).
— The supplementary requirements for non-sparking low power equipment are deleted (see Clause 13 of Edition 2014);
— The supplementary requirements for non-sparking current transformers are deleted (see Clause 14 of Edition 2014);
— The requirements for other non-sparking electrical equipment are deleted (see Clause 15 of Edition 2014);
— The general supplementary requirements for equipment producing arcs, sparks or hot surfaces are deleted (see Clause 16 of Edition 2014).
— The requirements for enclosed-break devices are deleted (see Clause 17 of Edition 2014);
— The voltage and current limiting for non-incendive components are added (see 7.2);
— The requirements for sealed devices are modified (see Clause 9; Clause 19 of Edition 2014);
— The requirements that the COT for device use in a luminaire shall be at least 20 K are deleted (see 19.5 of Edition 2014);
— The requirements for in accordance with the relevant industrial standards are added (see 10.2.1);
— The requirements for cells and batteries are added (see 10.2.2);
— The requirements for cable glands and conduit entries are modified (see 10.2.3; 20.2.2 of Edition 2014);
— The requirements for gasketed windows are modified (see 10.2.5.2; 20.2.4.2 of Edition 2014);
— The documentation requirements for gasket and seal requirements are added (see 10.2.6);
— The requirements for non-resilient seals are modified (see 10.2.7; 20.2.6 of Edition 2014);
— The requirements for internal fans with restricted breathing enclosures are added (see 10.2.9);
— The type tests for enclosed break devices and non incendive components are deleted (see 22.4 of Edition 2014);
— The preparation of non-incendive component samples is added (see 11.1.1);
— The requirements for electric strength test are modified (see 12.1; 22.5.2 of Edition 2014);
— The type tests of enclosed devices, screws, starters, lamps, ignitors and triggers are deleted (see Clause 22 of Edition 2014);
— All tests for batteries are deleted (see 22.11 and 22.12 of Edition 2014);
— All tests for electric machines are deleted (22.13 of Edition 2014);
— The requirements for routine tests are modified (see Clause 12; Clause 23 of Edition 2014);
— The requirements for markings are modified (see Clause 13; Clause 24 of 2014 edition);
— The requirements for documentation are modified (see Clause 14; and Clause 25 of Edition 2014);
— The requirements for instructions are added (see Clause 15);
This document has been redrafted and modified adoption of International Standard IEC 60079-15:2017 Explosive Atmospheres — Part 15: Equipment Protection by Type of Protection “n”.
The technical deviations between this document and the International Standard IEC 60079-15:2017, together with their justifications, are given below:
— The adjustments on technical deviations have been made for the normative references of this document to adapt to the technical conditions in China, which are mainly reflected in Clause 2 "Normative References”, with the following specific content:
IEC 60079-0 is replaced by GB/T 3836.1 which is redrafted and modified adoption of the international standard (see Clause 1, etc.);
IEC 60079-7 is replaced by GB/T 3836.3 which is redrafted and modified adoption of the international standard (see 10.2.2, etc.);
— The reference column with IEC 60079-0:2011 (Ed.6.0) in Table 1 of IEC 60079-15:2017 is deleted to be consistent with the Chinese standard version.
For the purposes of this document, the following editorial changes have also been made:
— In order to be consistent with the current standard series, the name of this document is modified to Explosive Atmospheres — Part 8: Equipment Protection by Type of Protection “n”;
— Note 1 in Table 1 regarding standard version information is modified;
— The note regarding GB/T 2900.35 is added (see Clause 3);
— Bibliography is modified.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by China Electrical Equipment Industry Association.
This document is under the jurisdiction of National Technical Committee 9 on Explosion Protected Electrical Apparatus of Standardization Administration of China (SAC/TC 9).
The previous editions of this document and documents replaced by this document are as follows:
— The first edition was issued in 1987 as GB 3836.8-1987, first edition was revised in 2003, and second revision was issued in 2014;
— This is the second revised edition.
Introduction
GB/T 3836 Explosive Atmospheres is prepared in order to establish the basic technical requirements for equipment used in explosive atmospheres and its application, covering the design, manufacture, inspection, selection, installation, inspection, maintenance, repair and site classification of equipment used in explosive atmospheres, and adopts the form of partial standards, including but not limited to the following parts:
— Part 1: Equipment — General Requirements;
— Part 2: Equipment Protection by Flameproof Enclosures “d”;
— Part 3: Equipment Protection by Increased Safety “e”;
— Part 4: Equipment Protection by Intrinsic Safety "i";
— Part 5: Equipment Protection by Pressurized Enclosure “p”;
— Part 6: Equipment Protection by Oil Immersion “o”;
— Part 7: Equipment Protection by Powder Filling “q”;
— Part 8: Equipment Protection by Type of Protection “n”;
— Part 9: Equipment Protection by Type of Protection “m”;
— Part 11: Material Characteristics for Gas and Vapour Classification — Test Methods and Data;
— Part 12: Material Characteristics for Combustible Dusts — Test Methods;
— Part 13: Equipment Repair, Overhaul and Reclamation;
— Part 14: Classification of Areas — Explosive Gas Atmosphere;
— Part 15: Electrical Installations Design, Selection and Erection;
— Part 16: Electrical Installations Inspection and Maintenance;
— Part 17: Equipment Protection by Pressurized Room “p” and Artificially Ventilated Room “v”;
— Part 18: Intrinsically Safe Electrical Systems;
— Part 20: Equipment with Equipment Protection Level (EPL) Ga;
— Part 21: Application of Quality Systems for Equipment Manufacture;
— Part 22: Protection of Equipment and Transmission System using Optical Radiation;
— Part 23: Group I, Category EPL Ma Equipment Intended to Remain Functional in Atmospheres Endangered by Firedamp and/or Coal Dust
— Part 24: Equipment Protection by Special Protection “s”;
— Part 25: Requirements for Process Sealing between Flammable Process Fluids and Electrical Systems;
— Part 26: Electrostatic Hazards — Guidance;
— Part 27: Electrostatic Hazards — Test;
— Part 28: Non-electrical Equipment for Potentially Explosive Atmospheres — Basic Method and Requirements;
— Part 29: Non-electrical Equipment for Explosive Atmospheres — Constructional Safety “c”, Control of Ignition Source “b”, Liquid Immersion “k;
— Part 30: Equipment and Components in Explosive Atmospheres in Underground Mines;
— Part 31: Equipment Dust Ignition Protection by Enclosure “t”;
— Part 32: Intrinsically Safe Systems with Electronically Controlled Spark Duration Limitation;
— Part 33: Equipment in Adverse Service Conditions;
— Part 34: Equipment Assemblies;
— Part 35: Classification of Areas for Explosive Dust Atmospheres;
Type of protection “n” is one of the most important explosion-proof types. In terms of standardization of this technology, China formulated GB 3836.8-1987 in 1987, and then revised it twice by IEC 60079-15 in 2003 and 2014. Since the release and implementation of the standard, there has been a certain new development in type of protection “n” explosion-proof technology. In terms of international standards, the current version of the corresponding standard is IEC 60079-15:2017, and its content and structure have been greatly adjusted. The requirements of non-sparking device "nA” and enclosed-break device “nC” have been transferred to other relevant standards, and the main technical content can also be applied to the situation of China. In order to adapt to the development of explosion-proof technology and industry and be consistent with the development of international standards, it is necessary to revise GB 3836.8.
Based on the main technical content of IEC 60079-15:2017, appropriate modifications have been made in this revision to adapt to the specific situation in China. This standard is a supplement and modification of GB/T 3836.1 as a specific type of protection part.
Explosive Atmospheres — Part 8: Equipment Protection by Type of Protection “n”
1 Scope
This document specifies requirements for the construction, testing and marking for Group II electrical equipment with type of protection “n” which includes: sealed devices “nC”, hermetically sealed devices “nC”, non-incendive components “nC” and restricted breathing enclosures “nR” intended for use in explosive gas atmospheres.
This document is applicable to electrical equipment where the rated input voltage does not exceed 15 kV r.m.s. AC or DC including where the internal working voltages of the Ex product exceeds 15 kV, for example starters for HID luminaires.
This document supplements and modifies the general requirements of GB/T 3836.1, except as indicated in Table 1. Where a requirement of this document conflicts with a requirement of GB/T 3836.1, the requirement of this document will take precedence.
Table 1 Relationship of this document to GB/T 3836.1
Clause of GB/T 3836.1 GB/T 3836.1 clause application to this document
Clause/Sub-clause number
(informative) Clause/Sub-clause title
(nominative) Protected sparking “nC” Restricted breathing “nR”
3 Terms and definitions Applies Applies
4 Equipment grouping
4.1 General Excluded Excluded
4.2 Group I Excluded Excluded
4.3 Group II Applies Applies
4.4 Group III Excluded Excluded
4.5 Equipment for a particular explosive atmosphere Applies Applies
5 Temperatures
5.1 Environmental influences Applies Applies
5.2 Service temperature Applies Applies
5.3 Maximum surface temperature
5.3.1 Determination of maximum surface temperature Applies Applies
5.3.2 Limitation of maximum surface temperature
5.3.2.1 Group I electrical equipment Excluded Excluded
5.3.2.2 Group II electrical equipment Applies Applies
5.3.2.3 Group III electrical equipment Excluded Excluded
5.3.3 Small component temperature for Group I and Group II electrical equipment Applies Excluded
5.3.4 Component temperature of smooth surfaces for Group I or Group II electrical equipment Applies Excluded
6 Requirements for all electrical apparatus
6.1 General Applies Applies
6.2 Mechanical strength of equipment Applies Applies
6.3 Opening time of equipment enclosure Excluded Applies
6.4 Circulating currents in enclosures (e.g. of large electrical machines) Applies Applies
6.5 Gasket retention Applies Applies
6.6 Electromagnetic and ultrasonic radiating equipment Applies Applies
7 Non-metallic enclosures or non-metallic parts of enclosures
7.1 General
7.1.1 Applicability Applies Applies
7.1.2 Specification of materials Applies Applies
7.2 Thermal endurance
7.2.1 Tests for thermal resistance Applies Applies
7.2.2 Material selection Applies Applies
7.2.3 Alternative qualification for elastomeric sealing O-rings Applies Applies
7.3 Resistance to ultraviolet light Applies Applies
7.4 Electrostatic charges on external non-metallic materials
7.4.1 Applicability Applies Applies
7.4.2 Avoidance of a build-up of electrostatic charge for Group I or Group II equipment Applies Applies
7.4.3 Avoidance of a build-up of electrostatic charge for Group III equipment Excluded Excluded
7.5 Attached external conductive parts Applies Applies
8 Metallic enclosures and metallic parts of enclosures
8.1 Material composition Applies Applies
8.2 Group I equipment Excluded Excluded
8.3 Group II equipment Applies Applies
8.4 Group III equipment Excluded Excluded
8.5 Copper alloy Applies Applies
9 Fasteners
9.1 General Applies Applies
9.2 Special fasteners Excluded Excluded
9.3 Holes for special fasteners Excluded Excluded
9.4 Hexagon socket set screws Excluded Excluded
10 Interlocking devices Excluded Excluded
11 Insulating bushings Applies Applies
12 (Reserved for future use) Excluded Excluded
13 Ex components Applies Applies
14 Connection facilities Applies Applies
15 Connection facilities for earthing and bonding conductors Applies Applies
16 Entries into enclosures Applies Applies
17 Supplementary requirements for electric machines Excluded Excluded
18 Supplementary requirements for switchgear Excluded
18.1 Flammable dielectric Excluded Applies
18.2 Disconnectors Excluded Applies
18.3 Group I equipment – Provisions for locking Excluded Excluded
1 8.4 Doors and covers Excluded Applies
19 Supplementary requirements for fuses Excluded Excluded
20 Supplementary requirements for plugs and sockets for field wiring connection
20.1 General Applies Applies
20.2 Explosive gas atmospheres Excluded Excluded
20.3 Explosive dust atmospheres Excluded Excluded
20.4 Energized plugs Applies Applies
21 Supplementary requirements for luminaires
21.1 General Applies Applies
21.2 Covers for luminaires of EPL Mb, EPL Gb or EPL Db Excluded Excluded
21.3 Covers for luminaires of EPL Gc or EPL Dc Applies Applies
21.4 Sodium lamps Applies Applies
22 Supplementary requirements for caplights and handlights
22.1 Group I caplights Excluded Excluded
22.2 Group II and Group III caplights and handlights Excluded Applies
23 Equipment incorporating cells and batteries Applies Applies
23.12 Replacement battery pack Applies Applies
24 Documentation Modified Modified
25 Compliance of prototype or sample with documents Applies Applies
26 Type tests Applies Applies
26.4 Tests of enclosures
26.4.1 Order of tests
26.4.1.1 Metallic enclosures, metallic parts of enclosures and glass or ceramic parts of enclosures Applies Applies
26.4.1.2 Non-metallic enclosures or non-metallic parts of enclosures
26.4.1.2.1 General Applies Applies
26.4.1.2.2 Class I equipment Excluded Excluded
26.4.1.2.3 Group II and Group III equipment Applies Applies
26.4.2 Impact resistance test Applies Applies
26.4.3 Drop test Applies Applies
26.4.4 Acceptance criteria Applies Applies
26.4.5 Degrees of protection provide by enclosure (IP) Applies Applies
26.5 Thermal tests
26.5.1 Temperature measurement Applies Applies
26.5.1.1 General Applies Applies
26.5.1.2 Service temperature Applies Applies
26.5.1.3 Maximum surface temperature Applies Applies
26.5.2 Thermal shock test Applies Applies
26.5.3 Small component ignition test (Group I and Group II) Applies Excluded
26.6 Torque test for insulating bushings Applies Applies
26.7 Non-metallic enclosures or non-metallic parts of enclosures
26.7.1 General Applies Applies
26.7.2 test temperature Applies Applies
26.8 Test for thermal endurance to heat Applies Applies
26.9 Test for thermal endurance to cold Applies Applies
26.10 Ultraviolet (UV) resistance test
26.10.1 General Applies Applies
26.10.2 Light exposure Applies Applies
26.10.3 Acceptance criteria Applies Applies
26.11 Test for resistance to chemical agents for Group I electrical equipment Excluded Excluded
26.12 Earth continuity Applies Applies
26.13 Surface resistance test of parts of enclosures of non-metallic materials Applies Applies
26.14 Measurement of capacitance
26.14.1 General Applies Applies
26.14.2 Test procedure Applies Applies
26.15 Verification of ratings of ventilating fans Excluded Excluded
26.16 Alternative qualification of elastomeric sealing O-rings Applies Applies
26.17 Transferred charge test Applies Applies
27 Routine test Applies Applies
28 Manufacturers responsibility Applies Applies
29 Marking
29.1 Applicability Applies Applies
29.2 Location Applies Applies
29.3 General Applies Applies
29.4 Ex marking for explosive gas atmospheres Applies Applies
29.5 Ex marking for explosive dust atmospheres Excluded Excluded
29.6 Combined types (or levels) of protection Applies Applies
29.7 Multiple types of protection Applies Applies
29.8 Ga equipment using two independent Gb types (or levels) of protection Excluded Excluded
29.9 Boundary wall Excluded Excluded
29.10 Ex components Applies Applies
29.11 Small Ex equipment and small Ex components Applies Applies
29.12 Extremely small equipment and extremely small Ex components Applies Applies
29.13 Warning markings Applies Applies
29.14 Battery Applies Applies
29.15 Electrical machines operated with a converter Applies Applies
29.16 Examples of marking Examples Examples
30 Instructions
30.1 General Applies Applies
30.2 Cells and batteries Applies Applies
30.3 Electric machines Excluded Excluded
30.4 Ventilating fans Excluded Excluded
30.5 Cable glands Applies Applies
Annex A Supplementary requirements for Ex cable glands Applies Applies
Annex B Requirements for Ex components Applies Applies
Annex C Example of rig for resistance to impact test Informative annex Informative annex
Annex D Motors supplied by converters Informative annex Informative annex
Annex E Temperature evaluation of electric machines Informative annex Informative annex
Annex F Guideline flowchart for tests of non-metallic enclosures or non-metallic parts of enclosures Informative annex Informative annex
Annex G Guidance flowchart for tests of cable glands Informative annex Informative annex
Annex H Shaft voltages resulting in motor bearing or shaft brush sparking. Discharge energy calculation Informative annex Informative annex
Annex I Special requirements for Group I electrical equipment Excluded Excluded
Appendix J Inspection procedure for obtaining Ex certificate Applies Applies
Applies: This requirement of GB/T 3836.1 is applied without change.
Excluded: This requirement of GB/T 3836.1 does not apply.
Modified: This requirement of GB/T 3836.1 is modified as detailed in this document.
Note 1: The clause number in the above table is shown for information only. The applicable requirements of GB/T 3836.1 are identified by the clause title which is normative. This document was written against the specific requirements of GB/T 3836.1.
Note 2: A shaded row in the above table indicates that this is a clause heading. In cases where the applicability is the same for all of the sub-clauses the ‘Applies’ or ‘Excluded’ is listed in the heading row and the sub-clauses are not expanded. Where the application of the individual sub-clauses may be different, these are expanded in the above table and the applicability for each is listed.
Note 3: A non-incendive component is limited in use to the particular circuit for which it has been shown to be non-ignition capable and, therefore, cannot be separately assessed as complying with this document.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3836.1 Explosive Atmospheres — Part 1: Equipment — General Requirements (GB 3836.1-2021, IEC 60079-0:2017, MOD)
GB/T 3836.3 Explosive Atmospheres — Part 3: Equipment Protection by Increased Safety “e” (GB/T 3836.3-2021, IEC 60079-7:2015, MOD)
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB/T 3836.1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC: http://www.electropedia.org/;
— ISO: http://www.iso.org/obp.
Note: Additional definitions applicable to explosive atmospheres can be found in GB/T 2900.35.
3.1
devices and components “nC”
3.1.1
hermetically-sealed device “nC”
device which is so constructed that it cannot be opened and is sealed effectively by fusion to prevent entry of an external atmosphere
3.1.2
non-incendive component “nC”
component having contacts for making or breaking a specified ignition capable circuit but in which the contacting mechanism is designed and constructed so that the component is not capable of causing ignition of the specified explosive gas atmosphere
Note: The enclosure of the non-incendive component is not intended to either exclude the explosive gas atmosphere or contain an explosion. This is usually applied to specially constructed switch contacts that are mechanically designed to quench any arc or spark so that they are not a source of ignition.
3.1.3
sealed device “nC”
device which is so constructed that it cannot be opened during normal service and is sealed effectively to prevent entry of an external atmosphere
3.2
normally sparking device
device with spacings in line with the industrial requirements and which produces arcs and sparks during normal operating conditions
Note: Normally sparking devices include switches, relays, and contactors not otherwise Ex protected.
3.3
restricted-breathing enclosure “nR”
enclosure that is designed to restrict the entry of gases, vapours and mists
3.4
sealing device
device employing a method other than encapsulation to prevent the flow of a gas or a liquid between equipment and a conduit or between separate parts of the equipment by providing sealing facilities
Note: This device is not a device covered by GB/T 3836.25.
3.5
separation
shortest distance through solid insulating material between two conductive parts
3.6
test port
facility to test the integrity of restricted breathing equipment in the field after installation, during initial inspection and during maintenance
3.7
type of protection "n"
type "n”
type of protection applied to electrical equipment such that, in normal operation and in certain specified regular expected occurrences, it is not capable of igniting a surrounding explosive gas atmosphere
Note: Additionally, the requirements of this document are intended to ensure that a malfunction capable of causing ignition is not likely to occur.
4 General
4.1 Equipment grouping and temperature classification
Equipment grouping and temperature classification shall be in accordance with the equipment grouping and temperature classification clauses of GB/T 3836.1.
4.2 Potential ignition sources
In normal operation and in certain regular expected occurrences specified by this document, the equipment shall not:
a) produce an operational arc or spark unless that arc or spark is prevented from causing ignition of a surrounding explosive atmosphere by one of the methods described in Clauses 7 to 10;
b) develop a maximum surface temperature in excess of the maximum value appropriate to the temperature class of the equipment, unless the temperature of the surface or hot spot is prevented from causing ignition of a surrounding explosive atmosphere by one of the methods described in Clauses 7 to 10 as appropriate, or is otherwise shown to be safe as specified in Clause 5.
4.3 Equipment requirements
Equipment or components which in normal operation produce arcs, sparks or hot surfaces which otherwise would be capable of igniting a surrounding atmosphere shall be protected against causing ignition by one or more of the following methods, all of which provide Equipment Protection Level Gc:
a) non-incendive component (see Clause 7);
b) hermetically sealed device (see Clause 8);
c) sealed device (see Clause 9);
d) restricted-breathing enclosure (see Clause 10).
5 Maximum Surface Temperature
The maximum surface temperature shall be determined in accordance with the determination of maximum temperature classification requirements of GB/T 3836.1. The surface to be considered shall be the external surface of the equipment including the surface of internal parts of non-incendive components to which the explosive gas atmosphere has access.
Note: This is often the outside surface of type of protection “nC” components located within level of protection “ec” equipment.
6 Requirements for Electrical Equipment
6.1 General
Electrical equipment with type of protection "n" shall comply with the requirements of this document and the applicable parts of GB/T 3836.1 for the method(s) of protection used.
6.2 Electric strength insulation from earth or frame
Where the electrical circuits within the equipment are not connected directly to the frame of the equipment or not intended to be connected to the frame in service, the insulation or separation distance used shall withstand without breakdown one of the following tests:
Foreword II
Introduction VIII
1 Scope
2 Normative References
3 Terms and Definitions
4 General
5 Maximum Surface Temperature
6 Requirements for Electrical Equipment
7 Requirements for Non-incendive Components
8 Requirements for Hermetically Sealed Devices
9 Requirements for Sealed Devices
10 Requirements for Restricted-breathing Enclosures
11 Type Test
12 Routine Verifications and Routine Tests
13 Marking
14 Documentation
15 Instructions
Bibliography
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is drafted in accordance with the rules given in the GB/T 1.1-2020 Directives for Standardization — Part 1: Rules for the Structure and Drafting of Standardizing Documents.
This part is Part 8 of GB/T 3836 Explosive Atmospheres. The following parts of GB/T 3836 have been published:
— Part 1: Equipment — General Requirements;
— Part 2: Equipment Protection by Flameproof Enclosures “d”;
— Part 3: Equipment Protection by Increased Safety “e”;
— Part 4: Equipment Protection by Intrinsic Safety "i";
— Part 5: Equipment Protection by Pressurized Enclosure “p”;
— Part 6: Equipment Protection by Oil Immersion “o”;
— Part 7: Equipment Protection by Powder Filling “q”;
— Part 8: Equipment Protection by Type of Protection “n”;
— Part 9: Equipment Protection by Type of Protection “m”;
— Part 11: Material Characteristics for Gas and Vapour Classification — Test Methods and Data;
— Part 12: Material Characteristics for Combustible Dusts — Test Methods;
— Part 13: Equipment Repair, Overhaul and Reclamation;
— Part 14: Classification of Areas — Explosive Gas Atmosphere;
— Part 15: Electrical Installations Design, Selection and Erection;
— Part 16: Electrical Installations Inspection and Maintenance;
— Part 17: Equipment Protection by Pressurized Room “p” and Artificially Ventilated Room “v”;
— Part 18: Intrinsically Safe Electrical Systems;
— Part 20: Equipment with Equipment Protection Level (EPL) Ga;
— Part 21: Application of Quality Systems for Equipment Manufacture;
— Part 22: Protection of Equipment and Transmission System using Optical Radiation;
— Part 23: Group I, Category EPL Ma Equipment Intended to Remain Functional in Atmospheres Endangered by Firedamp and/or Coal Dust
— Part 24: Equipment Protection by Special Protection “s”;
— Part 25: Requirements for Process Sealing between Flammable Process Fluids and Electrical Systems;
— Part 26: Electrostatic Hazards — Guidance;
— Part 27: Electrostatic Hazards — Test;
— Part 28: Non-electrical Equipment for Potentially Explosive Atmospheres — Basic Method and Requirements;
— Part 29: Non-electrical Equipment for Explosive Atmospheres — Constructional Safety “c”, Control of Ignition Source “b”, Liquid Immersion “k;
— Part 30: Equipment and Components in Explosive Atmospheres in Underground Mines;
— Part 31: Equipment Dust Ignition Protection by Enclosure “t”;
— Part 32: Intrinsically Safe Systems with Electronically Controlled Spark Duration Limitation;
— Part 33: Equipment in Adverse Service Conditions;
— Part 34: Equipment Assemblies;
— Part 35: Classification of Areas for Explosive Dust Atmospheres;
This standard replaces GB 3836.8-2014 Explosive Atmospheres — Part 8: Equipment Protection by Type of Protection “n” in whole, and the following technical deviations have been made with respect to the GB 3836.8-2014:
— The range of internal working voltage is modified (see Clause 1; Clause 1 of Edition 2014);
— The non-sparking device “nA” is deleted and transferred to GB/T 3836.3, "ec” (see Clause 3 of Edition 2014);
— The enclosed-break device “nC” is deleted and transferred to GB/T 3836.2, "dc” (see Clause 3 of Edition 2014);
— The term and definition of hermetically-sealed device “nC” is modified (see Clause 3; Clause 3 of Edition 2014);
— The term and definition of normally sparking device is added (see Clause 3);
— The provisions of small components are deleted (see 5.2 of Edition 2014);
— The requirements for connection facilities and terminal compartments are deleted (see Clause 7 of Edition 2014);
— The supplementary requirements for non-sparking electrical rotating machines are deleted (see Clause 8 of Edition 2014);
— The supplementary requirements for non-sparking fuses and fuse assemblies are deleted for instrumentation (see Clause 9 of 2014 Edition);
— The supplementary requirements for non-sparking plugs and sockets are deleted (see Clause 10 of Edition 2014);
— The supplementary requirements for non-sparking luminaires are deleted (see Clause 11 of Edition 2014);
— The supplementary requirements for equipment incorporating non-sparking cells and batteries are deleted (see Clause 12 of Edition 2014).
— The supplementary requirements for non-sparking low power equipment are deleted (see Clause 13 of Edition 2014);
— The supplementary requirements for non-sparking current transformers are deleted (see Clause 14 of Edition 2014);
— The requirements for other non-sparking electrical equipment are deleted (see Clause 15 of Edition 2014);
— The general supplementary requirements for equipment producing arcs, sparks or hot surfaces are deleted (see Clause 16 of Edition 2014).
— The requirements for enclosed-break devices are deleted (see Clause 17 of Edition 2014);
— The voltage and current limiting for non-incendive components are added (see 7.2);
— The requirements for sealed devices are modified (see Clause 9; Clause 19 of Edition 2014);
— The requirements that the COT for device use in a luminaire shall be at least 20 K are deleted (see 19.5 of Edition 2014);
— The requirements for in accordance with the relevant industrial standards are added (see 10.2.1);
— The requirements for cells and batteries are added (see 10.2.2);
— The requirements for cable glands and conduit entries are modified (see 10.2.3; 20.2.2 of Edition 2014);
— The requirements for gasketed windows are modified (see 10.2.5.2; 20.2.4.2 of Edition 2014);
— The documentation requirements for gasket and seal requirements are added (see 10.2.6);
— The requirements for non-resilient seals are modified (see 10.2.7; 20.2.6 of Edition 2014);
— The requirements for internal fans with restricted breathing enclosures are added (see 10.2.9);
— The type tests for enclosed break devices and non incendive components are deleted (see 22.4 of Edition 2014);
— The preparation of non-incendive component samples is added (see 11.1.1);
— The requirements for electric strength test are modified (see 12.1; 22.5.2 of Edition 2014);
— The type tests of enclosed devices, screws, starters, lamps, ignitors and triggers are deleted (see Clause 22 of Edition 2014);
— All tests for batteries are deleted (see 22.11 and 22.12 of Edition 2014);
— All tests for electric machines are deleted (22.13 of Edition 2014);
— The requirements for routine tests are modified (see Clause 12; Clause 23 of Edition 2014);
— The requirements for markings are modified (see Clause 13; Clause 24 of 2014 edition);
— The requirements for documentation are modified (see Clause 14; and Clause 25 of Edition 2014);
— The requirements for instructions are added (see Clause 15);
This document has been redrafted and modified adoption of International Standard IEC 60079-15:2017 Explosive Atmospheres — Part 15: Equipment Protection by Type of Protection “n”.
The technical deviations between this document and the International Standard IEC 60079-15:2017, together with their justifications, are given below:
— The adjustments on technical deviations have been made for the normative references of this document to adapt to the technical conditions in China, which are mainly reflected in Clause 2 "Normative References”, with the following specific content:
IEC 60079-0 is replaced by GB/T 3836.1 which is redrafted and modified adoption of the international standard (see Clause 1, etc.);
IEC 60079-7 is replaced by GB/T 3836.3 which is redrafted and modified adoption of the international standard (see 10.2.2, etc.);
— The reference column with IEC 60079-0:2011 (Ed.6.0) in Table 1 of IEC 60079-15:2017 is deleted to be consistent with the Chinese standard version.
For the purposes of this document, the following editorial changes have also been made:
— In order to be consistent with the current standard series, the name of this document is modified to Explosive Atmospheres — Part 8: Equipment Protection by Type of Protection “n”;
— Note 1 in Table 1 regarding standard version information is modified;
— The note regarding GB/T 2900.35 is added (see Clause 3);
— Bibliography is modified.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by China Electrical Equipment Industry Association.
This document is under the jurisdiction of National Technical Committee 9 on Explosion Protected Electrical Apparatus of Standardization Administration of China (SAC/TC 9).
The previous editions of this document and documents replaced by this document are as follows:
— The first edition was issued in 1987 as GB 3836.8-1987, first edition was revised in 2003, and second revision was issued in 2014;
— This is the second revised edition.
Introduction
GB/T 3836 Explosive Atmospheres is prepared in order to establish the basic technical requirements for equipment used in explosive atmospheres and its application, covering the design, manufacture, inspection, selection, installation, inspection, maintenance, repair and site classification of equipment used in explosive atmospheres, and adopts the form of partial standards, including but not limited to the following parts:
— Part 1: Equipment — General Requirements;
— Part 2: Equipment Protection by Flameproof Enclosures “d”;
— Part 3: Equipment Protection by Increased Safety “e”;
— Part 4: Equipment Protection by Intrinsic Safety "i";
— Part 5: Equipment Protection by Pressurized Enclosure “p”;
— Part 6: Equipment Protection by Oil Immersion “o”;
— Part 7: Equipment Protection by Powder Filling “q”;
— Part 8: Equipment Protection by Type of Protection “n”;
— Part 9: Equipment Protection by Type of Protection “m”;
— Part 11: Material Characteristics for Gas and Vapour Classification — Test Methods and Data;
— Part 12: Material Characteristics for Combustible Dusts — Test Methods;
— Part 13: Equipment Repair, Overhaul and Reclamation;
— Part 14: Classification of Areas — Explosive Gas Atmosphere;
— Part 15: Electrical Installations Design, Selection and Erection;
— Part 16: Electrical Installations Inspection and Maintenance;
— Part 17: Equipment Protection by Pressurized Room “p” and Artificially Ventilated Room “v”;
— Part 18: Intrinsically Safe Electrical Systems;
— Part 20: Equipment with Equipment Protection Level (EPL) Ga;
— Part 21: Application of Quality Systems for Equipment Manufacture;
— Part 22: Protection of Equipment and Transmission System using Optical Radiation;
— Part 23: Group I, Category EPL Ma Equipment Intended to Remain Functional in Atmospheres Endangered by Firedamp and/or Coal Dust
— Part 24: Equipment Protection by Special Protection “s”;
— Part 25: Requirements for Process Sealing between Flammable Process Fluids and Electrical Systems;
— Part 26: Electrostatic Hazards — Guidance;
— Part 27: Electrostatic Hazards — Test;
— Part 28: Non-electrical Equipment for Potentially Explosive Atmospheres — Basic Method and Requirements;
— Part 29: Non-electrical Equipment for Explosive Atmospheres — Constructional Safety “c”, Control of Ignition Source “b”, Liquid Immersion “k;
— Part 30: Equipment and Components in Explosive Atmospheres in Underground Mines;
— Part 31: Equipment Dust Ignition Protection by Enclosure “t”;
— Part 32: Intrinsically Safe Systems with Electronically Controlled Spark Duration Limitation;
— Part 33: Equipment in Adverse Service Conditions;
— Part 34: Equipment Assemblies;
— Part 35: Classification of Areas for Explosive Dust Atmospheres;
Type of protection “n” is one of the most important explosion-proof types. In terms of standardization of this technology, China formulated GB 3836.8-1987 in 1987, and then revised it twice by IEC 60079-15 in 2003 and 2014. Since the release and implementation of the standard, there has been a certain new development in type of protection “n” explosion-proof technology. In terms of international standards, the current version of the corresponding standard is IEC 60079-15:2017, and its content and structure have been greatly adjusted. The requirements of non-sparking device "nA” and enclosed-break device “nC” have been transferred to other relevant standards, and the main technical content can also be applied to the situation of China. In order to adapt to the development of explosion-proof technology and industry and be consistent with the development of international standards, it is necessary to revise GB 3836.8.
Based on the main technical content of IEC 60079-15:2017, appropriate modifications have been made in this revision to adapt to the specific situation in China. This standard is a supplement and modification of GB/T 3836.1 as a specific type of protection part.
Explosive Atmospheres — Part 8: Equipment Protection by Type of Protection “n”
1 Scope
This document specifies requirements for the construction, testing and marking for Group II electrical equipment with type of protection “n” which includes: sealed devices “nC”, hermetically sealed devices “nC”, non-incendive components “nC” and restricted breathing enclosures “nR” intended for use in explosive gas atmospheres.
This document is applicable to electrical equipment where the rated input voltage does not exceed 15 kV r.m.s. AC or DC including where the internal working voltages of the Ex product exceeds 15 kV, for example starters for HID luminaires.
This document supplements and modifies the general requirements of GB/T 3836.1, except as indicated in Table 1. Where a requirement of this document conflicts with a requirement of GB/T 3836.1, the requirement of this document will take precedence.
Table 1 Relationship of this document to GB/T 3836.1
Clause of GB/T 3836.1 GB/T 3836.1 clause application to this document
Clause/Sub-clause number
(informative) Clause/Sub-clause title
(nominative) Protected sparking “nC” Restricted breathing “nR”
3 Terms and definitions Applies Applies
4 Equipment grouping
4.1 General Excluded Excluded
4.2 Group I Excluded Excluded
4.3 Group II Applies Applies
4.4 Group III Excluded Excluded
4.5 Equipment for a particular explosive atmosphere Applies Applies
5 Temperatures
5.1 Environmental influences Applies Applies
5.2 Service temperature Applies Applies
5.3 Maximum surface temperature
5.3.1 Determination of maximum surface temperature Applies Applies
5.3.2 Limitation of maximum surface temperature
5.3.2.1 Group I electrical equipment Excluded Excluded
5.3.2.2 Group II electrical equipment Applies Applies
5.3.2.3 Group III electrical equipment Excluded Excluded
5.3.3 Small component temperature for Group I and Group II electrical equipment Applies Excluded
5.3.4 Component temperature of smooth surfaces for Group I or Group II electrical equipment Applies Excluded
6 Requirements for all electrical apparatus
6.1 General Applies Applies
6.2 Mechanical strength of equipment Applies Applies
6.3 Opening time of equipment enclosure Excluded Applies
6.4 Circulating currents in enclosures (e.g. of large electrical machines) Applies Applies
6.5 Gasket retention Applies Applies
6.6 Electromagnetic and ultrasonic radiating equipment Applies Applies
7 Non-metallic enclosures or non-metallic parts of enclosures
7.1 General
7.1.1 Applicability Applies Applies
7.1.2 Specification of materials Applies Applies
7.2 Thermal endurance
7.2.1 Tests for thermal resistance Applies Applies
7.2.2 Material selection Applies Applies
7.2.3 Alternative qualification for elastomeric sealing O-rings Applies Applies
7.3 Resistance to ultraviolet light Applies Applies
7.4 Electrostatic charges on external non-metallic materials
7.4.1 Applicability Applies Applies
7.4.2 Avoidance of a build-up of electrostatic charge for Group I or Group II equipment Applies Applies
7.4.3 Avoidance of a build-up of electrostatic charge for Group III equipment Excluded Excluded
7.5 Attached external conductive parts Applies Applies
8 Metallic enclosures and metallic parts of enclosures
8.1 Material composition Applies Applies
8.2 Group I equipment Excluded Excluded
8.3 Group II equipment Applies Applies
8.4 Group III equipment Excluded Excluded
8.5 Copper alloy Applies Applies
9 Fasteners
9.1 General Applies Applies
9.2 Special fasteners Excluded Excluded
9.3 Holes for special fasteners Excluded Excluded
9.4 Hexagon socket set screws Excluded Excluded
10 Interlocking devices Excluded Excluded
11 Insulating bushings Applies Applies
12 (Reserved for future use) Excluded Excluded
13 Ex components Applies Applies
14 Connection facilities Applies Applies
15 Connection facilities for earthing and bonding conductors Applies Applies
16 Entries into enclosures Applies Applies
17 Supplementary requirements for electric machines Excluded Excluded
18 Supplementary requirements for switchgear Excluded
18.1 Flammable dielectric Excluded Applies
18.2 Disconnectors Excluded Applies
18.3 Group I equipment – Provisions for locking Excluded Excluded
1 8.4 Doors and covers Excluded Applies
19 Supplementary requirements for fuses Excluded Excluded
20 Supplementary requirements for plugs and sockets for field wiring connection
20.1 General Applies Applies
20.2 Explosive gas atmospheres Excluded Excluded
20.3 Explosive dust atmospheres Excluded Excluded
20.4 Energized plugs Applies Applies
21 Supplementary requirements for luminaires
21.1 General Applies Applies
21.2 Covers for luminaires of EPL Mb, EPL Gb or EPL Db Excluded Excluded
21.3 Covers for luminaires of EPL Gc or EPL Dc Applies Applies
21.4 Sodium lamps Applies Applies
22 Supplementary requirements for caplights and handlights
22.1 Group I caplights Excluded Excluded
22.2 Group II and Group III caplights and handlights Excluded Applies
23 Equipment incorporating cells and batteries Applies Applies
23.12 Replacement battery pack Applies Applies
24 Documentation Modified Modified
25 Compliance of prototype or sample with documents Applies Applies
26 Type tests Applies Applies
26.4 Tests of enclosures
26.4.1 Order of tests
26.4.1.1 Metallic enclosures, metallic parts of enclosures and glass or ceramic parts of enclosures Applies Applies
26.4.1.2 Non-metallic enclosures or non-metallic parts of enclosures
26.4.1.2.1 General Applies Applies
26.4.1.2.2 Class I equipment Excluded Excluded
26.4.1.2.3 Group II and Group III equipment Applies Applies
26.4.2 Impact resistance test Applies Applies
26.4.3 Drop test Applies Applies
26.4.4 Acceptance criteria Applies Applies
26.4.5 Degrees of protection provide by enclosure (IP) Applies Applies
26.5 Thermal tests
26.5.1 Temperature measurement Applies Applies
26.5.1.1 General Applies Applies
26.5.1.2 Service temperature Applies Applies
26.5.1.3 Maximum surface temperature Applies Applies
26.5.2 Thermal shock test Applies Applies
26.5.3 Small component ignition test (Group I and Group II) Applies Excluded
26.6 Torque test for insulating bushings Applies Applies
26.7 Non-metallic enclosures or non-metallic parts of enclosures
26.7.1 General Applies Applies
26.7.2 test temperature Applies Applies
26.8 Test for thermal endurance to heat Applies Applies
26.9 Test for thermal endurance to cold Applies Applies
26.10 Ultraviolet (UV) resistance test
26.10.1 General Applies Applies
26.10.2 Light exposure Applies Applies
26.10.3 Acceptance criteria Applies Applies
26.11 Test for resistance to chemical agents for Group I electrical equipment Excluded Excluded
26.12 Earth continuity Applies Applies
26.13 Surface resistance test of parts of enclosures of non-metallic materials Applies Applies
26.14 Measurement of capacitance
26.14.1 General Applies Applies
26.14.2 Test procedure Applies Applies
26.15 Verification of ratings of ventilating fans Excluded Excluded
26.16 Alternative qualification of elastomeric sealing O-rings Applies Applies
26.17 Transferred charge test Applies Applies
27 Routine test Applies Applies
28 Manufacturers responsibility Applies Applies
29 Marking
29.1 Applicability Applies Applies
29.2 Location Applies Applies
29.3 General Applies Applies
29.4 Ex marking for explosive gas atmospheres Applies Applies
29.5 Ex marking for explosive dust atmospheres Excluded Excluded
29.6 Combined types (or levels) of protection Applies Applies
29.7 Multiple types of protection Applies Applies
29.8 Ga equipment using two independent Gb types (or levels) of protection Excluded Excluded
29.9 Boundary wall Excluded Excluded
29.10 Ex components Applies Applies
29.11 Small Ex equipment and small Ex components Applies Applies
29.12 Extremely small equipment and extremely small Ex components Applies Applies
29.13 Warning markings Applies Applies
29.14 Battery Applies Applies
29.15 Electrical machines operated with a converter Applies Applies
29.16 Examples of marking Examples Examples
30 Instructions
30.1 General Applies Applies
30.2 Cells and batteries Applies Applies
30.3 Electric machines Excluded Excluded
30.4 Ventilating fans Excluded Excluded
30.5 Cable glands Applies Applies
Annex A Supplementary requirements for Ex cable glands Applies Applies
Annex B Requirements for Ex components Applies Applies
Annex C Example of rig for resistance to impact test Informative annex Informative annex
Annex D Motors supplied by converters Informative annex Informative annex
Annex E Temperature evaluation of electric machines Informative annex Informative annex
Annex F Guideline flowchart for tests of non-metallic enclosures or non-metallic parts of enclosures Informative annex Informative annex
Annex G Guidance flowchart for tests of cable glands Informative annex Informative annex
Annex H Shaft voltages resulting in motor bearing or shaft brush sparking. Discharge energy calculation Informative annex Informative annex
Annex I Special requirements for Group I electrical equipment Excluded Excluded
Appendix J Inspection procedure for obtaining Ex certificate Applies Applies
Applies: This requirement of GB/T 3836.1 is applied without change.
Excluded: This requirement of GB/T 3836.1 does not apply.
Modified: This requirement of GB/T 3836.1 is modified as detailed in this document.
Note 1: The clause number in the above table is shown for information only. The applicable requirements of GB/T 3836.1 are identified by the clause title which is normative. This document was written against the specific requirements of GB/T 3836.1.
Note 2: A shaded row in the above table indicates that this is a clause heading. In cases where the applicability is the same for all of the sub-clauses the ‘Applies’ or ‘Excluded’ is listed in the heading row and the sub-clauses are not expanded. Where the application of the individual sub-clauses may be different, these are expanded in the above table and the applicability for each is listed.
Note 3: A non-incendive component is limited in use to the particular circuit for which it has been shown to be non-ignition capable and, therefore, cannot be separately assessed as complying with this document.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3836.1 Explosive Atmospheres — Part 1: Equipment — General Requirements (GB 3836.1-2021, IEC 60079-0:2017, MOD)
GB/T 3836.3 Explosive Atmospheres — Part 3: Equipment Protection by Increased Safety “e” (GB/T 3836.3-2021, IEC 60079-7:2015, MOD)
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB/T 3836.1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC: http://www.electropedia.org/;
— ISO: http://www.iso.org/obp.
Note: Additional definitions applicable to explosive atmospheres can be found in GB/T 2900.35.
3.1
devices and components “nC”
3.1.1
hermetically-sealed device “nC”
device which is so constructed that it cannot be opened and is sealed effectively by fusion to prevent entry of an external atmosphere
3.1.2
non-incendive component “nC”
component having contacts for making or breaking a specified ignition capable circuit but in which the contacting mechanism is designed and constructed so that the component is not capable of causing ignition of the specified explosive gas atmosphere
Note: The enclosure of the non-incendive component is not intended to either exclude the explosive gas atmosphere or contain an explosion. This is usually applied to specially constructed switch contacts that are mechanically designed to quench any arc or spark so that they are not a source of ignition.
3.1.3
sealed device “nC”
device which is so constructed that it cannot be opened during normal service and is sealed effectively to prevent entry of an external atmosphere
3.2
normally sparking device
device with spacings in line with the industrial requirements and which produces arcs and sparks during normal operating conditions
Note: Normally sparking devices include switches, relays, and contactors not otherwise Ex protected.
3.3
restricted-breathing enclosure “nR”
enclosure that is designed to restrict the entry of gases, vapours and mists
3.4
sealing device
device employing a method other than encapsulation to prevent the flow of a gas or a liquid between equipment and a conduit or between separate parts of the equipment by providing sealing facilities
Note: This device is not a device covered by GB/T 3836.25.
3.5
separation
shortest distance through solid insulating material between two conductive parts
3.6
test port
facility to test the integrity of restricted breathing equipment in the field after installation, during initial inspection and during maintenance
3.7
type of protection "n"
type "n”
type of protection applied to electrical equipment such that, in normal operation and in certain specified regular expected occurrences, it is not capable of igniting a surrounding explosive gas atmosphere
Note: Additionally, the requirements of this document are intended to ensure that a malfunction capable of causing ignition is not likely to occur.
4 General
4.1 Equipment grouping and temperature classification
Equipment grouping and temperature classification shall be in accordance with the equipment grouping and temperature classification clauses of GB/T 3836.1.
4.2 Potential ignition sources
In normal operation and in certain regular expected occurrences specified by this document, the equipment shall not:
a) produce an operational arc or spark unless that arc or spark is prevented from causing ignition of a surrounding explosive atmosphere by one of the methods described in Clauses 7 to 10;
b) develop a maximum surface temperature in excess of the maximum value appropriate to the temperature class of the equipment, unless the temperature of the surface or hot spot is prevented from causing ignition of a surrounding explosive atmosphere by one of the methods described in Clauses 7 to 10 as appropriate, or is otherwise shown to be safe as specified in Clause 5.
4.3 Equipment requirements
Equipment or components which in normal operation produce arcs, sparks or hot surfaces which otherwise would be capable of igniting a surrounding atmosphere shall be protected against causing ignition by one or more of the following methods, all of which provide Equipment Protection Level Gc:
a) non-incendive component (see Clause 7);
b) hermetically sealed device (see Clause 8);
c) sealed device (see Clause 9);
d) restricted-breathing enclosure (see Clause 10).
5 Maximum Surface Temperature
The maximum surface temperature shall be determined in accordance with the determination of maximum temperature classification requirements of GB/T 3836.1. The surface to be considered shall be the external surface of the equipment including the surface of internal parts of non-incendive components to which the explosive gas atmosphere has access.
Note: This is often the outside surface of type of protection “nC” components located within level of protection “ec” equipment.
6 Requirements for Electrical Equipment
6.1 General
Electrical equipment with type of protection "n" shall comply with the requirements of this document and the applicable parts of GB/T 3836.1 for the method(s) of protection used.
6.2 Electric strength insulation from earth or frame
Where the electrical circuits within the equipment are not connected directly to the frame of the equipment or not intended to be connected to the frame in service, the insulation or separation distance used shall withstand without breakdown one of the following tests:
Contents of GB/T 3836.8-2021
Foreword II
Introduction VIII
1 Scope
2 Normative References
3 Terms and Definitions
4 General
5 Maximum Surface Temperature
6 Requirements for Electrical Equipment
7 Requirements for Non-incendive Components
8 Requirements for Hermetically Sealed Devices
9 Requirements for Sealed Devices
10 Requirements for Restricted-breathing Enclosures
11 Type Test
12 Routine Verifications and Routine Tests
13 Marking
14 Documentation
15 Instructions
Bibliography
