IP Rating refers to the International Protection or Ingress Protection of electrical enclosures, against the intrusion of solid objects, water, dust and accidental contact to live parts, as defined by IEC 60529. The rating comprises the letters "IP" followed by two numbers (and an optional letter), where the numbers and letters refer to conformity to levels of protection.
The Wikipedia article gives a fairly detailed account of IP ratings. Therefore this page is only intended to be a summary of the ratings and more importantly, highlight some key points from IEC 60529 that are commonly overlooked.
Summary of IP Ratings
|Level||First Number (Protected against solids of size:)||Second Number (Proection against water)|
|0||No protection against contact and ingress of objects||Not protected|
|1||>50 mm - Any large surface of the body, such as the back of a hand, but no protection against deliberate contact with a body part||Dripping water - Dripping water (vertically falling drops) shall have no harmful effect.|
|2||>12.5 mm - Fingers or similar objects||Dripping water when tilted up to 15° - Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position.|
|3||>2.5 mm - Tools, thick wires, etc.||Spraying water - Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.|
|4||>1 mm - Most wires, screws, etc.||Splashing water - Water splashing against the enclosure from any direction shall have no harmful effect.|
|5||Dust protected - Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact||Water jets - Water projected by a nozzle (6.3mm) against enclosure from any direction shall have no harmful effects.|
|6||Dust tight - No ingress of dust; complete protection against contact||Powerful water jets - Water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects.|
|7||N/A||Immersion up to 1 m - Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1 m of submersion).|
|8||N/A||Immersion beyond 1 m - The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. Normally, this will mean that the equipment is hermetically sealed. However, with certain types of equipment, it can mean that water can enter but only in such a manner that produces no harmful effects.|
An IP54 enclosure is dust protected (1st number = 5) and protected against splashing wayer (2nd number = 4).
An IP66/67 enclosure is dual protected, both for immersion up to 1m and powerful water jets. Note that it is not always true that an enclosure with a single rating such as IP68 is suitable for use in lower IP environments, such as IP66 (for more details, see the next section below).
Important Points from IEC 60529
Section 6 of IEC 60529 makes an important point about backward compliance of IP ratings for water protection, as per the extract below:
"Up to and including second characteristic numeral 6, the designation implies compliance 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 7 or 8 only is considered unsuitable for exposure to water jets (designated by second characteristic numeral 5 or 6) and need not comply with requirements for numeral 5 or 6 unless it is dual coded."