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Enclosure protection against ingress of solid objects and liquids
Enclosure protection against ingress of solid objects and liquids (photo credit: dmaeuropa.com)

Enclosure protection (IP) code

As you already probably know, IP stands for Ingress Protection. International Electrotechnical Commission – IEC 60529 “Degrees of protection provided by enclosures (IP Code).”. NEMA offers a similar rating system.

In order to protect live parts of equipment being contacted by foreign solid bodies or liquid, and also to prevent persons or livestock from coming into contact with live or moving parts, such equipment is housed inside an enclosure.

The degree of protection offered by such an enclosure is indicated by an index of protection (IP) code, as shown in Table 1 below.


First numeral // Mechanical protection

No.Description
0No protection of persons against contact with live or moving parts inside the enclosure. No protection of equipment against ingress of solid foreign bodies.
1Protection against accidental or inadvertent contact with live or moving parts inside the enclosure by a large surface of the human body, e.g. a hand, but not protection against deliberate access to such parts. Protection against ingress of large solid foreign bodies.
2Protection against contact with live or moving parts inside the enclosure by fingers. Protection against ingress of medium-size solid foreign bodies (12.5 mm spheres).
3Protection against contact with live or moving parts inside the enclosure by tools, wires or such objects of thickness greater than 2.5 mm. Protection against ingress of small foreign bodies.
4Protection against contact with live or moving parts inside the enclosure by tools, wires or such objects of thickness greater than 1 mm. Protection against ingress of small solid foreign bodies.
5Complete protection against contact with live or moving parts inside the enclosure. Protection against harmful deposits of dust. The ingress of dust is not totally prevented, but dust cannot enter in an amount sufficient to interfere with satisfactory operation of the equipment enclosed.
6Complete protection against contact with live or moving parts inside the enclosures. Protection against ingress of dust.

Second numeral // Liquid (water) protection

No.Description
0No protection.
1Protection against drops of condensed water. Drops of condensed water falling on the enclosure shall have no harmful effect.
2Protection against drops of liquid. Drops of falling liquid shall have no harmful effect when the enclosure is tilted at any angle up to 15° from the vertical.
3Protection against rain. Water falling in rain at an angle equal to or smaller than 60° with respect to the vertical shall have no harmful effect.
4Protection against splashing. Liquid splashed from any direction shall have no harmful effect.
5Protection against water jets. Water projected by a nozzle from any direction under stated conditions shall have no harmful effect.
6Protection against conditions on ships’ decks (deck with water-tight equipment). Water from heavy seas shall not enter the enclosures under prescribed conditions.
7Protection against immersion in water. It must not be possible for water to enter the enclosure under stated conditions of pressure and time.
8Protection against indefinite immersion in water under specified pressure. It must not be possible for water to enter the enclosure.
XIndicates no specified protection.

It will be seen from Table 1 that, for instance, an enclosure to IP 56 is dustproof and waterproof.

These notions of protection have a large influence on the design of equipment because protection has to be assessed not only by the external enclosure, but also by internal enclosures or parts of internal enclosures (partitions, shutters, etc).

Therefore the degree of protection of persons has to be defined also for internal parts which can initiate a direct contact during an operation, for instance when withdrawing a circuit- breaker.

In addition, even if an enclosure provides the required degree of protection, it is also necessary that it cannot be removed partially or totally. The point does not concern pieces of equipment such as motors, transformers, etc, but it is of primary importance for some compartments of assemblies which have to be accessible during servicing of the equipment.

Two kinds of compartments are considered in this case:

1. Those which are opened only rarely (bus bars) and for which bolted covers can be considered as satisfactory. Opening them being not a simple operation, it is supposed that adequate precautions dictated by safety requirements will be taken.

2. Those which may have to be opened during normal operation of the equipment. They are generally closed by doors which can be locked or blocked by an additional control system which completes the protection provided by the enclosure.

During all these service and maintenance operations the electrical continuity of the enclosure must not be interrupted whatever the position of the equipment is.


NEMA rating

How do I cross-reference with an IP rating?

Two widely accepted rating systems are the NEMA and the IP codes. NEMA, short for National Electric Manufacturers’ Association, is commonly specified at installations in the U.S.A. IP, which is an abbreviation for International Protection, is derived from the IEC. IP and IEC are more common in Europe and Asia.

Here are the NEMA 250 classifications:

No.Description
1Intended for use primarily to provide a degree of protection against limited amounts of falling dirt.
3Outdoor protection against rain, sleet, windblown dust, and damage from external ice formation.
3ROutdoor, protection against rain, sleet, and damage from external ice formation.
3SOutdoor, protection against rain, sleet, windblown dust, and to provide for operation of external mechanisms

when ice laden.

4Indoor/Outdoor, protection against windblown dust and rain, splashing water, hose-directed water and damage from external ice formation.
4XIndoor/Outdoor, protection against corrosion, windblown dust and rain, splashing water, hose-directed water and damage from external ice formation.
6Indoor/Outdoor, protection against hose-directed water, the entry of water during occasional temporary submersion at a limited depth and damage from external ice formation.
6PIndoor/Outdoor, protection against hose-directed water, the entry of water during prolonged submersion at a limited depth and damage from external ice formation.
12Indoor, protection against circulating dust, falling dirt and dripping non-corrosive liquids.
12KType 12 with knockouts

A Brief Comparison of NEMA 250 and IEC 60529

NEMA EnclosureIEC Enclosure
1IP10
3IP54
3RIP14
3SIP54
4 and 4XIP56
6 and 6PIP67
12 and 12KIP52

References:
  • Electric Wiring: Domestic – B. Scaddan
  • Schneider Electric Cahier technique 166

About Author //

author-pic

Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears.Professional in AutoCAD programming and web-design.Present on

5 Comments


  1. karthick selvaraj
    Apr 22, 2015

    Its helpful..


  2. Jamie C
    Apr 15, 2014

    Great article. It is also important to ensure that the continuity ingress protection of the enclosure is maintained when installing electrical equipment or components.

    We get a lot of questions from our customers when it comes to installing equipment into enclosures, even if the both have adequate IP ratings, the ratings usually doesn’t relate to the protection offered to the enclosure entry.

    We’ve explained this point in more detail here: http://www.etscc.co.uk/blog-home/maintaining-ip66-cable-gland-enclosure-entry-q-and-a


  3. ragundo
    Mar 29, 2014

    I think there’s a mistake in the last table.
    No way a NEMA 4X cabinet can be equivalent to a IEC IP55 one
    NEMA4/4X is equivalent to IP65 / IP66


  4. muqtar
    Mar 26, 2014

    good and useful article thanks!!!


  5. Althaf Abdulla
    Mar 26, 2014

    you are providing tremendous knowledge

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