How to specify IP ratings for enclosures

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Schneider Electric believes that a lack of understanding of IP ratings is leading to enclosures being specified with inappropriate levels of protection. Moreover, some IP ratings do not conform to international standards and are not relevant to the intended use of the products to which they have been applied.

Darren Hodson from Schneider Electric writes: "The system of IP ratings is misleading many specifiers and resulting in higher costs than are strictly necessary. The common mistake is to assume that the higher the IP rating, the better the equipment inside the enclosure will be protected against weather conditions. This is not always a guarantee and the degree of protection offered by a specific enclosure has to be considered in conjunction with the precise performance requirements of the application."

IP ratings are defined in the international standard IEC 60529 Degrees of protection provided by enclosures (IP-Code), which is published in the UK as BS EN 60529. Degrees of protection are specified by the letters IP followed by two or more digits. The first digit, a number 1 to 6, reflects the degree of protection against the ingress of objects as well as the protection of persons against contact with live parts of the equipment within the enclosure. The second digit, a number from 1 to 8, relates to the protection of equipment within the enclosure against harmful ingress of water. Either digit can be replaced by 'X' for an unspecified condition.

Schneider Electric recommends that specifiers should not automatically opt for a higher IP rating because this does not necessarily mean that the enclosure will perform better in the intended application. For example, an enclosure may pass the test for a high level of protection against ingress of water but in-situ may be subject to environmental conditions that could cause rusting or other degradation.

The problem with IP69K

According to Hodson, one of the most common misconceptions relates to enclosures rated IP69K. He says: "This actually stems from a German national standard and has no international recognition. The IP69K test specification was initially developed for electronic equipment on road vehicles as a rating for high-pressure and high-temperature washdown applications. However, it has no real meaning in the UK because it is not defined in a British or international standard - and has been found to give different results in different test houses. The result of this situation is that enclosures rated IP69K can vary between manufacturers and might not even pass the tests for lower IP codes.

"To ensure the correct combination of performance and cost-effectiveness, the specifier has to carefully examine the specific conditions that will apply in each application and prescribe the enclosure most suitable for that application, which is not necessarily the one with the highest IP rating. And, of course, the most important thing is to use an enclosure rating that is recognised by IEC or British standards."

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