NEMA and IP Ratings

Comparison Between NEMA Enclosure Type Numbers and IEC Enclosure Classification Designations

IEC Publication 60529 Classification of Degrees of Protection Provided by Enclosures provides a system for specifying the enclosures of electrical equipment on the basis of the degrees of protection provided by the enclosure. IEC 60529 does not specify degrees of protection against mechanical damage of equipment, risk of explosions, or conditions such as moisture (produced for example by condensation), corrosive vapours, fungus, or vermin.

The NEMA Standard for Enclosures for Electrical Equipment does test for environmental conditions such as corrosion, rust, icing, oil, and coolants. For this reason, and because the test and evaluations for other characteristics are not identical, the IEC Enclosure Classification Designations cannot be exactly equated with the enclosure Type numbers in this standard. The IEC designations consists of the letters IP followed by two numerals.

The first characteristic numeral indicates the degree of protection provided by the enclosure with respect to the persons and solid foreign objects entering the enclosure.

The second characteristic numeral indicates the degree of protection provided by the enclosure with respect to the harmful ingress of water. Table A -1 provides an equivalent conversion for the enclosure Type Numbers in this standard to the IEC Enclosure Classifications Designations.

The enclosure type numbers meet or exceed the test requirements for the IEC classification; for this reason Table A -1 cannot be used to convert from IEC Classifications to enclosure Type numbers.