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

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 [this term is 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.

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 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 [this term is 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.

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.

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

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.

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).

Figure 2. Description of the IP Code elements

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).

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).

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.

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.

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.

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

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.