GB/T 4942.2-1993 English PDF (GBT4942.2-1993)

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GB/T 4942.2-1993: Degrees of protection provided by enclosures for low-voltage apparatus
GB/T 4942.2-1993
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
GB/T 4942.2-93
Replacing GB/T 4942.2-85
Degrees of Protection Provided by Enclosures
for Low-Voltage Apparatus
ISSUED ON. APRIL 20, 1993
IMPLEMENTED ON. DECEMBER 1, 1993
Issued by. State Bureau of Technical Supervision
Table of Contents
1 Subject Content and Application Scope ... 3 
2 Normative References ... 3 
3 Terms, Symbols and Codes ... 3 
4 Protection types and requirements ... 5 
5 Marking ... 6 
6 Technical Requirements ... 6 
7 Test Requirements ... 11 
8 Testing Method and Conformity Assessment ... 12 
Appendix A Common degree of protection (supplemented) ... 22 
Additional Explanation ... 23 
This Standard equivalently adopts International Standard IEC 947-1 (1988)
"Low-voltage Switchgear and Controlgear - Part 1. General Rules". And it references
to the requirements and rules on low-voltage apparatus enclosure protection degree
as specified in IEC 529 (1989) "Degrees of Protection Provided by Enclosures (IP
Code)".
1 Subject Content and Application Scope
This Standard specifies the requirements in classification, grading, marking, definition,
testing method, and requalification of enclosure protection degree of low-voltage
electrical apparatus (hereinafter referred as to electric apparatus).
This Standard is applicable to enclosure protection grading of electric apparatus.
This Standard is not applicable to protection of electric apparatus against physical
damage, explosive / active gas, condensing wet (e.g. dew), mold, damage by insect,
etc.
This Standard is also not applicable to stress effect caused by short-circuit operation.
2 Normative References
GB 2900.18 Electrotechnical terminology - Low voltage apparatus
GB 14048.1 Low-voltage switchgear and controlgear - General rules
3 Terms, Symbols and Codes
3.1 Terms
3.1.1 Enclosure
A part providing protection of equipment against certain external influences and, in
any direction, protection against direct access or contact to alive part and running part.
Note. Barriers, shapes of openings or any other means - whether attached to the enclosure or
formed by the enclosed equipment - suitable to prevent or limit direct access or contact of
external solid subject to alive part and running part are considered as a part of the enclosure,
except when they can be removed without the use of a key or tool.
3.1.2 Degree of protection
The extent of protection provided by an enclosure against, ingress of solid foreign
objects to alive part or moving component in enclosure and/or against ingress of water
and verified by standardized test methods.
3.1.3 IP code
A coding system to indicate the degrees of protection provided by an enclosure,
consisted of letters "IP" and two characteristic numerals and additional letter.
3.1.4 Adequate clearance
A distance to prevent contact or approach of an access testing apparatus (ball, finger,
bar, or probe) to a alive part or moving component (except hazardous parts like
smooth moving axle and similar component).
3.1.5 Excluded
Preventing certain positions of human body, hand tool, metallic thread / bar, or probe;
and / or, even though accessing, keeping adequate distance to alive part or hazard
moving components (except hazardous parts like smooth moving axle and similar
component).
3.1.6 Hazardous part
Accessed or exposed hazardous component.
3.1.7 Hazardous live part
Conducting body or conductive component with electric shock hazard.
3.1.8 Hazardous mechanical part
Moving component with exposure hazard, except smooth rotating axle.
3.1.9 Direct contact
Exposure of human or domestic animals to alive component.
Note.
① "Live parts" refer to hazardous live part.
② "Exposure" excludes accessing high pressure live parts of less than electric adequate
distance.
3.1.10 Protection provided by an enclosure against direct contact
The protection of persons against direct contact of hazardous alive components in
enclosure.
Note. this protection may be provided by means of the enclosure itself, or by means of barriers
as part of the enclosure or distances inside the enclosure.
3.1.11 Adequate clearance for protection against direct contact
A distance to prevent contact or approach of an access testing apparatus to a
hazardous part.
3.1.12 Access probe
A test probe simulating in a conventional manner a part of a person or a tool, or the
like, held by a person to verify adequate clearance from hazardous parts.
3.1.13 Object probe
A test probe simulating a solid foreign object to verify the possibility of ingress into an
enclosure
3.1.14 Opening
A gap or aperture in an enclosure which exists or may be formed by the application of
a test probe at the specified force.
3.1.15 Besides the terms specified in 3.1~ 3.1.14, the terms and definitions related
to this Standard, specified in GB/T 2900.18 "Electrotechnical terminology - Low
voltage apparatus", are applied.
3.2 Symbols and Codes
IP. characteristic letter indicate Symbol "degree of protection".
W. indicating additional letters used under specific climate conditions.
N. indicating additional letters used under specific dust ambient conditions.
L. indicating additional letters used under specified solid foreign object conditions.
4 Protection types and requirements
4.1 This Standard specifies electric apparatus enclosure coming with the following
two types.
4.1.1 Excluded person's contact or access to alive part in enclosure and/or contact
moving component except hazardous parts like smooth moving axle and similar
component, and excluded access of solid foreign object into enclosure inside of
electric apparatus.
4.1.2 Excluded access of water into electric apparatus enclosure inside and causing
hazardous effect.
4.2 This Standard only considers enclosures that meet the design requirements in
all aspects; under regular service condition, the materials and craft of the enclosure
materials shall be able to that the properties meet the protection requirement in this
Standard.
4.3 The protective measures like barrier, arranged outside of the enclosure in
account of personal safety, shall not be deemed as a part of enclosure; the barrier
(insulation guard) in enclosure, arranged to prevent solid foreign objects again
accessing alive part and moving component, shall be deemed as a part of enclosure.
4.4 On enclosure bottom, bleed hole that may be arranged to prevent water inlet
accumulation or dew, must meet the requirements of hole opening / closing, and the
diameter of the hole shall not be less than 2.5 mm.
5 Marking
5.1 The marking shall be apparent, easy to identify and difficult to fade away.
5.2 The characteristic letter and numeral to indicate protection degree shall be
marked on electric apparatus nameplate; if in a difficulty, they may be marked on
enclosure; for open type electric apparatus, they may not be marked.
5.3 Where parts of electric apparatus have different protection degree, the lowest
protection degree shall be indicated firstly; if the ones of other parts need be indicated,
they shall be marked respectively according to the protection degree of corresponding
parts.
5.4 Where the assembly mode of an electric apparatus affects its protection degree,
the manufactory shall mark the pre-determined assembly mode on nameplate,
assembly instruction or other relevant documents.
5.5 Common protect...