Don’t be misled by IP ratings, warns Schneider Electric10 August 2010

A lack of understanding of IP ratings is leading to inappropriate specification of enclosures, according to Schneider Electric.

The company's Darren Hodson also warns that some IP ratings do not have an international meaning and so may not be relevant to their intended use.

"The system of IP ratings is misleading many specifiers and resulting in higher costs than are strictly necessary," says Hodson. "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," he explains.

He makes the point that 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 IEC 60529 standard 'Degrees of protection provided by enclosures', published in the UK as BS EN 60529. Degrees of protection are then 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 'x' for an unspecified condition.

According to Darren Hodson, one of the most common misconceptions relates to enclosures rated IP69K. "This actually stems from a German national standard and has no international recognition."

And he adds: "The IP69K test specification was initially developed for electronic equipment on road vehicles as a rating for high-pressure and high-temperature wash-down applications… The result is that enclosures rated IP69K can vary between manufacturers and might not even pass the tests for lower IP codes."

Brian Tinham

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