Degree of Protection of Enclosure (IP Code): What Is it? (Definition, Meaning)

Definitions

Degree of protection: the extent of protection provided by an enclosure against access to hazardous parts, against ingress of solid foreign objects and/or against ingress of water and verified by standardized test methods [defined in the IEC 60529].

The definition of the term in question, borrowed from IEC 60529, is used in IEC 60044-8, IEC 61984 and IEC 62271-202.

IEC 60050-426 defines the term “degree of protection of enclosure, IP (abbreviation)”: numerical classification preceded by the symbol IP applied to the enclosure of equipment to provide:

  • protection of persons against contact with, or approach to, live parts and against contact with moving
  • parts (other than smooth rotating shafts and the like) inside the enclosure,
  • protection of the equipment against ingress of solid foreign objects, and
  • where indicated by the classification, protection of the equipment against harmful ingress of water

Note 1 to entry: The conditions for other than rotating machines are specified in IEC 60529, Degrees of protection provided by enclosures (IP Code).
Note 2 to entry: The detailed test requirements for rotating electric machines are in IEC 60034-5, Rotating electrical machines – Part 5: Degrees of protection provided by the integral design of rotating electrical machines (IP code) – Classification.
Note 3 to entry: The enclosure which provides the degree of protection IP is not necessarily the same as the equipment enclosure providing the Type of Protection.
Note 4 to entry: An enclosure which provides the degree of protection required by one of the Types of Protection will have been subjected to other tests prior to the tests for degree of protection.

A definition borrowed from IEC 60050-426 is given to the term “degree of protection of enclosure” in IEC 61892-1 and to the term “degree of protection of enclosure, IP” in IEC 62561-6.

IEC 60529 defined the term “protection provided by an enclosure against access to hazardous parts”: the protection of persons against:

  • contact with hazardous low-voltage live parts,
  • contact with hazardous mechanical parts,
  • approach to hazardous high-voltage live parts below adequate clearance inside an enclosure.

A note to the definition of the term explains that this protection can be provided:

  • by means of the enclosure itself,
  • by means of barriers as part of the enclosure or distances inside the enclosure.

A note in IEC 60529 uses the term “barrier”. Clauses 3.12 and 3.13 of IEC 61140 define the following specific terms:

Electrically protective obstacle: part preventing unintentional contact by a human or livestock with a live part, but not preventing such contact by deliberate action.

IEC 61140 [clause 3.12]

Electrically protective barrier: part providing protection against contact by a human or livestock with a live part from any usual direction of access.

IEC 61140 [clause 3.13]

The barrier, like the enclosure, is designed to prevent access to hazardous parts from any direction. The obstacle prevents only unintentional access to hazardous parts.

As specified in IEC 61140 clause 5.2.4.1:

Obstacles are intended to protect skilled or instructed persons but their use is not permitted for the protection of ordinary persons.

IEC 61140 [clause 5.2.4.1]

According to IEC 60529, enclosures are primarily designed to protect people from access to hazardous electrical and mechanical parts.

The former are parts under voltage that exceeds the maximum permissible value of extra-low voltage for the specified operating conditions of electrical equipment.

When operating electrical equipment in rooms without increased hazard, the maximum allowable value of extra-low voltage is 50 VAC and 120 VDC, and in rooms with high risk and, especially, in especially hazardous areas, it can be no more than 12 VAC and 30 VDC.

Hazardous mechanical parts are usually considered to be moving parts. Human contact with such parts can result in serious injury and even death. Other mechanical parts, such as those that become hot during operation of electrical equipment, can also present a hazard.

The second function assigned by IEC 60529 to enclosures is to protect electrical equipment against adverse effects of the environment. The enclosures limit or prevent the penetration of external solid objects, such as dust, and water, in particular rain, inside the electrical equipment.

Meaning

The degree of protection that the enclosure can provide is set by a special IP code that sets the limits of human protection against access to hazardous parts, as well as against the ingress of external solid objects and water.

As a summary, the term “degree of protection” can only be applied to enclosures in the context of the requirements set out in IEC 60529. However, in some regulatory documents this term is used incorrectly. Consider one example of the incorrect use of the term “degree of protection”.

IEC 61140 5.2.3.1 states that protective barriers or enclosures shall prevent:

– in the case of low-voltage installations and equipment, access to hazardous-live-parts by providing a degree of protection against electric shock of at least IPXXB or IP2X of IEC 60529 and, for readily accessible horizontal top surfaces of protective barriers or enclosures, at least IPXXD or IP4X

IEC 61140, 5.2.3.1

– in the case of high-voltage installations and equipment, entering the danger zone by providing a degree of protection of at least IPXXB or IP2X of IEC 60529, and consideration shall be given to providing a degree of protection of at least IPXXD or IP4X for readily accessible horizontal top surfaces of protective barriers or enclosures

IEC 61140, 5.2.3.1

The first requirement presented uses an incorrect phrase: « degree of protection against electric shock … IP2X … ». Indeed, as shown above, the degree of protection describes the ability of an enclosure to protect both persons and electrical equipment. The specific code IPX2 prescribes that a person must be protected against finger contact with hazardous electrical and mechanical parts and that external solid objects with a diameter of 12.5 mm or more must not penetrate the enclosure. Two of the three protections provided by the enclosure have nothing to do with protection against electric shock.

The degree of protection against electric shock can be considered as a characteristic of electrical equipment, by which the way in which such protection is accomplished is indicated. IEC 61140 has classified electrical equipment into classes 0, I, II, III and has established the fundamental requirements for protection against electric shock for each class. Therefore, the degree of protection against electric shock is established through the classification of the electrical equipment in question.

Based on a short analysis of the requirements of IEC 61140, it can be argued that the first requirement has a terminological error that significantly distorts its meaning. Therefore it should have specified, as in the second requirement: by providing a degree of protection … IP2X … .

IP Codes Explained

IP Code: a coding system to indicate the degrees of protection provided by an enclosure against access to hazardous parts, ingress of solid foreign objects, ingress of water and to give additional information in connection with such protection [defined in the IEC 60529].

IEC 60044-8, IEC 61000-5-7, IEC 61984 and IEC 62271-1 use the definition of the term in question, which is derived from IEC 60529.

IP Code Designations

Section 4, ” Designations,” of IEC 60529 specifies the requirements for the IP code and explains its constituent parts. Section 4.1 “Arrangement of the IP Code” of IEC 60529 gives the structure of the IP code shown in Figure 1 below.

Arrangement of the IP Code

The degree of protection provided by an enclosure is indicated by the IP Code in the following way:

Arrangement of the ip code
Figure 1. Arrangement of the IP code

Where a characteristic numeral is not required to be specified, it shall be replaced by the letter “X” (“XX” if both numerals are omitted).
Additional letters and/or supplementary letters may be omitted without replacement.
Where more than one supplementary letter is used, the alphabetic sequence shall apply.
If an enclosure provides different degrees of protection for different intended mounting arrangements, the relevant degrees of protection shall be indicated by the manufacturer in the instructions related to the respective mounting arrangements.

Elements of the IP Code and their Meanings

IEC 60529, “Elements of the IP Code and their meanings”, subsection 4.2, provides a general explanation of all the elements that make up the IP Code.

A brief description of the IP Code elements is given in the following chart. Full details are specified in the clauses indicated in the last column (See Figure 2).

Description of the IP Code elements
Figure 2. Description of the IP Code elements

Examples for the Use of Letters in the IP Code

Section 4.3, “Examples for the Use of Letters in the IP Code,” of IEC 60529 provides several acceptable variants of the IP code that illustrate the use of letters. The following examples are to explain the use and arrangement of letters in the IP Code.

  • IP44 – no letters, no options;
  • IPX5 – omitting first characteristic numeral;
  • IP2X – omitting second characteristic numeral;
  • IP20C – using additional letter;
  • IPXXC – omitting both characteristic numerals, using additional letter;
  • IPX1C – omitting first characteristic numeral, using additional letter;
  • IP3XD – omitting second characteristic numeral, using additional letter;
  • IP23S – using supplementary letter;
  • IP21CM – using additional letter and supplementary letter;
  • IPX5/IPX7/IPX9 – giving three degrees of protection by an enclosure against water jets, temporary immersion and high pressure and temperature water jet for “versatile” application.

For more comprehensive examples see clause 9 [IEC 60529].

Subsection 4.3 of IEC 60529 also states that more detailed examples of IP code are presented in Section 9, “Examples of Designations with the IP Code”, which consists of two subsections. Subsection 9.1 “IP Code not using optional letters” shows Code IP34 (Figure 3).

IP Code not using optional letters
Figure 3. IP Code not using optional letters (IP34 code)

An enclosure with this designation (IP Code):

(3) – protects persons, handling tools having a diameter of 2,5 mm and greater, against access to hazardous parts;
– protects the equipment inside the enclosure against ingress of solid foreign objects having a diameter of 2,5 mm and greater;
(4) – protects the equipment inside the enclosure against harmful effects due to water splashed against the enclosure from any direction.

Subsection 9.2 “IP Code using optional letters” of IEC 60529 presents the IP23CS code (Figure 4).

IP Code using optional letters
Figure 4. IP Code using optional letters

An enclosure with this designation (IP Code):

(2) – protects persons against access to hazardous parts with fingers;
– protects the equipment inside the enclosure against ingress of solid foreign objects having a diameter of 12,5 mm and greater;
(3) – protects the equipment inside the enclosure against the harmful effects due to water sprayed against the enclosure;

(C) – protects persons handling tools having a diameter of 2,5 mm and greater and a length not exceeding 100 mm against access to hazardous parts (the tool may penetrate the enclosure up to its full length);
(S) – is tested for protection against harmful effects due to the ingress of water when all the parts of the equipment are stationary.

Degree of Protection of Enclosure (IP Code) Requirements

Degrees of Protection Against Access to Hazardous Parts and Against Solid Foreign Objects Indicated by the First Characteristic Numeral

The requirements for the degrees of protection indicated by the first characteristic numeral are laid down in section 5 “Degrees of protection against access to hazardous parts and against solid foreign objects indicated by the first characteristic numeral” of IEC 60529.

The designation with a first characteristic numeral implies that conditions stated in both 5.1 [1] and 5.2 [1] are met.

The first characteristic numeral indicates that:

  • the enclosure provides protection of persons against access to hazardous parts by preventing or limiting the ingress of a part of the human body or an object held by a person;
  • and simultaneously the enclosure provides protection of equipment against the ingress of solid foreign objects.

An enclosure shall only be designated with a stated degree of protection indicated by the first characteristic numeral if it also complies with all lower degrees of protection.

However, the tests establishing compliance with any one of the lower degrees of protection need not necessarily be carried out provided that these tests would obviously be met if applied.

Protection Against Access to Hazardous Parts

Table 1 gives brief descriptions and definitions for the degrees of protection against access to hazardous parts. Degrees of protection listed in this table shall be specified only by the first characteristic numeral and not by reference to the brief description or definition.

To comply with the conditions of the first characteristic numeral, adequate clearance shall be kept between the access probe and hazardous parts.

First characteristic numeral Degree of protection Test conditions, see
Brief description Definition
0 Non-protected
1 Protected against access to hazardous parts with the back of a hand The access probe, sphere of 50 mm ∅, shall have adequate clearance from hazardous parts 12.2
2 Protected against access to hazardous parts with a finger The jointed test finger of 12 mm ∅, 80 mm length, shall have adequate clearance form hazardous parts 12.2
3 Protected against access to hazardous parts with a tool The access probe of 2,5 mm ∅ shall not penetrate 12.2
4 Protected against access to hazardous parts with a wire The access probe of 1,0 mm ∅ shall not penetrate 12.2
5 Protected against access to hazardous parts with a wire The access probe of 1,0 mm ∅ shall not penetrate 12.2
6 Protected against access to hazardous parts with a wire The access probe of 1,0 mm ∅ shall not penetrate 12.2
NOTE – In the case of the first characteristic numerals 3, 4, 5 and 6, protection against access to hazardous parts is satisfied if adequate clearance is kept. Due to the simultaneous requirement specified in table 2, the definition “shall not penetrate” is given in table 1.
Table 1 – Degrees of protection against access to hazardous parts indicated by the first characteristic numeral
Protection Against Solid Foreign Objects

Table 2 gives brief descriptions and the definitions for the degrees of protection against the penetration of solid foreign objects including dust.

Degrees of protection listed in this table shall only be specified by the first characteristic numeral and not by reference to the brief description or definition.
The protection against the ingress of solid foreign objects implies that the object probes up to numeral 2 in table 2 shall not fully penetrate the enclosure. This means that the full diameter of the sphere shall not pass through an opening. in the enclosure. Object probes for numerals 3 and 4 shall not penetrate the enclosure at all.

Dust-protected enclosures to numeral 5 allow a limited quantity of dust to penetrate under certain conditions.
Dust-tight enclosures to numeral 6 do not allow any dust to penetrate.

NOTE. Enclosures assigned a first characteristic numeral of 1 to 4 generally exclude both regularly and irregularly shaped solid foreign objects provided that three mutually perpendicular dimensions of the object exceed the appropriate figure in column 3 of table 2.

First characteristic numeral Degree of protection Test conditions, see
Brief description Definition
0 Non-protected
1 Protected against solid foreign objects of 50 mm ∅ and greater The object probe, sphere of 50 mm ∅, shall not fully penetrate 1) 13.2
2 Protected against solid foreign objects of 12,5 mm ∅ and greater The object probe, sphere of 12,5 mm ∅, shall not fully penetrate 1) 13.2
3 Protected against solid foreign objects of 2,5 mm ∅ and greater The object probe, sphere of 2,5 mm ∅, shall not penetrate at all 1) 13.2
4 Protected against solid foreign objects of 1,0 mm ∅ and greater The object probe of 1,0 mm ∅, shall not penetrate at all 1)< 13.2
5 Dust-protected Ingress of dust is not totally prevented, but dust shall not penetrate in a quantity to interfere with satisfactory operation of the apparatus or to impair safety 13.4 and 13.5
6 Dust-tight No ingress of dust 13.4 and 13.6
1) The full diameter of the object probe shall not pass through an opening of the enclosure.
Table 2 – Degrees of protection against solid foreign objects indicated by the first characteristic numeral

Degrees of Protection Against Ingress of Water Indicated by the Second Characteristic Numeral

The requirements for the degrees of protection indicated by the second characteristic digit are laid down in IEC 60529, Section 6, “Degrees of Protection Against Ingress of Water Indicated by the Second Characteristic Numeral”.

The second characteristic numeral indicates the degree of protection provided by enclosures with respect to harmful effects on the equipment due to the ingress of water.

The tests for the second characteristic numeral are carried out with fresh water. The actual protection may not be satisfactory if cleaning operations with high pressure and temperature water jet outside the requirements of second characteristic numeral 9 and/or solvents are
used.

Table 4 gives brief descriptions and definitions of the protection for the degrees represented by the second characteristic numeral. Degrees of protection listed in this table shall be specified only by the second characteristic numeral and not by reference to the brief description or definition.

Up to and including second characteristic numeral 6, the designation implies compliance also with the requirements for all lower characteristic numerals. However, the tests establishing compliance with any one of the lower degrees of protection need not necessarily be carried
out provided that these tests obviously would be met if applied.

An enclosure designated with second characteristic numeral 9 only is considered unsuitable for exposure to water jets (designated by second characteristic numeral 5 or 6) and immersion in water (designated by second characteristic numeral 7 or 8) and need not comply with requirements for numeral 5,6,7 or 8 unless it is multiple coded as follows:

Enclosure passes test for: Designation and marking Range of application
water jets second characteristic numeral temporary/continuous immersion second characteristic numeral
5 7 IPX5/IPX7 Versatile
5 8 IPX5/IPX8 Versatile
6 7 IPX6/IPX7 Versatile
6 8 IPX6/IPX8 Versatile
9 7 IPX7/IPX9 Versatile
9 8 IPX8/IPX9 Versatile
5 and 9 7 IPX5/IPX7/IPX9 Versatile
5 and 9 8 IPX5/IPX8/IPX9 Versatile
6 and 9 7 IPX6/IPX7/IPX9 Versatile
6 and 9 8 IPX6/IPX8/IPX9 Versatile
7 IPX7 Restricted
8 IPX8 Restricted
9 IPX9 Restricted
5 and 9 IPX5/IPX9 Versatile
6 and 9 IPX6/IPX9 Versatile
Table 3

Enclosures for “versatile” application indicated in the last column shall meet requirements for exposure to both water jets and temporary or continuous immersion.

Enclosures for “restricted” application indicated in the last column are considered suitable only for the conditions to which they were tested.

Second characteristic numeral Degree of protection Test conditions, see
Brief description Definition
0 Non-protected
1 Protected against vertically falling water drops Vertically falling drops shall have no harmful effects 14.2.1
2 Protected against vertically falling water drops when enclosure tilted up to 15° Vertically falling drops shall have no harmful effects when the enclosure is tilted at any angle up to 15° on either side of the vertical 14.2.2
3 Protected against spraying water Water sprayed at an angle up to 60° on either side of the vertical shall have no harmful effects 14.2.3
4 Protected against splashing water Water splashed against the enclosure from any direction shall have no harmful effects 14.2.4
5 Protected against water jets Water projected in jets against the enclosure from any direction shall have no harmful effects 14.2.5
6 Protected against powerful water jets Water projected in powerful jets against the enclosure from any direction shall have no harmful effects 14.2.6
7 Protected against the effects of temporary immersion in water Ingress of water in quantities causing harmful effects shall not be possible when the enclosure is temporarily immersed in water under standardized conditions of pressure and time 14.2.7
8 Protected against the effects of continuous immersion in water Ingress of water in quantities causing harmful effects shall not be possible when the enclosure is continuously immersed in water under conditions which shall be agreed between manufacturer and user but which are more severe than for numeral 7 14.2.8
9 Protected against high pressure and temperature water jets Water projected at high pressure and high temperature against the enclosure from any direction shall not have harmful effects 14.2.9
Table 4 – Degrees of protection against water indicated by the second characteristic numeral

Degrees of Protection Against Access to Hazardous Parts Indicated by the Additional Letter

The additional letter indicates the degree of protection of persons against access to hazardous parts.

Additional letters are only used:

  • if the actual protection against access to hazardous parts is higher than that indicated by the first characteristic numeral;
  • or if only the protection against access to hazardous parts is indicated, the first characteristic numeral being then replaced by an X.

For example, such higher protection may be provided by barriers, suitable shape of openings or distances inside the enclosure.

Table 5 gives access probes considered by convention as representative of parts of the human body or objects held by a person and the definitions for the degrees of protection against access to hazardous parts, indicated by additional letters.

An enclosure shall only be designated with a stated degree of protection indicated by the additional letter if the enclosure also complies with all lower degrees of protection. However, the tests establishing compliance with any one of the lower degrees of protection need not necessarily be carried out provided that these tests obviously would be met if applied.

Additional letter Degree of protection Test conditions, see
Brief description Definition
A Protected against access with the back of the hand The access probe, sphere of 50 mm ∅, shall have adequate clearance from hazardous parts 15.2
B Protected against access with a finger The jointed test finger of 12 mm ∅, 80 mm length, shall have adequate clearance form hazardous parts 15.2
C Protected against access with a tool The access probe of 2,5 mm ∅, 100 mm length, shall have adequate clearance from hazardous parts 15.2
D Protected against access with a wire The access probe of 1,0 mm ∅, 100 mm length, shall have adequate clearance from hazardous parts 15.2
Table 5 – Degrees of protection against access to hazardous parts indicated by the additional letter

Supplementary Letters

In the relevant product standard, supplementary information may be indicated by a supplementary letter following the second characteristic numeral or the additional letter.

Such exceptional cases shall conform with the requirements of this basic safety standard and the product standard shall state clearly the additional procedure to be carried out during tests for such a classification.

The letters listed below have already been designated and have the significance as stated:

LetterSignificance
HHigh-voltage apparatus
MTested for harmful effects due to the ingress of water when the movable parts of the equipment (for example, the rotor of a rotating machine) are in motion
STested for harmful effects due to the ingress of water when the movable parts of the equipment (for example, the rotor of a rotating machine) are stationary
WSuitable for use under specified weather conditions and provided with additional protective features or processes
Table 6

NOTE. In the first edition of IEC 60529 the letter “W” with the same meaning was placed immediately after the code letters “IP”.

NOTE. Other letters may be used in product standards.

The absence of the letters S and M implies that the degree of protection does not depend on whether parts of the equipment are in motion or not. This may necessitate tests being done under both conditions. However, the test establishing compliance with one of these conditions is generally sufficient, provided that the test in the other condition obviously would be met if applied.

United States (NEMA Rating)

In the U.S., the National Electrical Manufacturers Association defines NEMA enclosure types in NEMA standard number 250. The following table outlines which IEC 60529 IP code each respective NEMA guideline meets. Ratings between the two standards are not directly equivalent: NEMA ratings also require additional product features and tests (such as functionality under icing conditions, enclosures for hazardous areas, knock-outs for cable connections and others) not addressed by IP ratings.

wikipedia.org
NEMA enclosureIP Code
1IP20
2IP22
3, 3X, 3S, 3SXIP55
3R, 3RXIP24
4, 4XIP44, IP66, IP65
5IP53
6IP67
6PIP68
12, 12K, 13IP54
Table 7 – NEMA rating

Conclusion

The most important function that all electrical equipment must provide is protection against electric shock. Protection against access to hazardous-live- parts by means of electrical enclosures is one element of this protection. In addition, electrical equipment must provide adequate protection against access to hazardous mechanical parts, also provided by its enclosures.

International standards for electrical equipment therefore always specify the minimum allowable degrees of protection against access to dangerous parts which their enclosures must provide. In doing so, they refer to the requirements of IEC 60529 according to which the enclosures are tested.

References

  1. IEC 60529:1989+AMD1:1999+AMD2:2013 CSV Consolidated version
  2. IEC 61140:2016 RLV  Redline version