NEMA Ratings for Enclosures

NEMA ratings for enclosures are performance standards set by the National Electrical Manufacturers Association (NEMA). They have entered the vocabulary of electrical enclosures users so fully that the use of the terms NEMA 3R, NEMA 4X and others have become practically generic. An enclosure rated for either NEMA12 or NEMA4 protects hazardous parts access; ingress of solid foreign objects (dirt, dust, fibers, lint, etc.); and ingress of water (splashing to hose-down) at different levels. Other levels (3R, 4X, etc.) offer very specific enhanced levels of protection for unique installation environments. NEMA ratings are most often used for installation in industrial applications and environments and are primarily used in North America.

What’s the Difference between IP and NEMA?

While IP (Ingress Protection) ratings offer insight into an enclosure’s capabilities as they relate to the intrusion of water and foreign objects, they do have limitations. NEMA (National Electrical Manufacturers Association) ratings provide construction requirements to help installers avoid devaluing an enclosure’s capabilities by using inappropriate materials or methods.

Since they cover most normal environmental conditions, IP ratings are generally sufficient for typical consumers. On the other hand, because they cover things such as tampering, oil, corrosives, acids, and icing, NEMA ratings often provide better guidance for organizations that work in oil and gas, as well as other industries that leave enclosures exposed to harsh or uncommon materials

How to Compare NEMA and IP

While IP ratings, used worldwide, cover only water and solid object ingress, NEMA standards cover corrosion resistance and atmospheric gases (acetylene or gasoline, for example), plus ratings divide between hazardous and non-hazardous environments. Additional IEC standards define protection against other contaminants and threats. Because the two systems are based on different variables, there’s no direct correlation or conversion between NEMA and IP ratings. NEMA includes tests not addressed by IP, so IP ratings don’t necessarily meet NEMA standards (e.g., NEMA specifies performance during icing conditions; IP standards don’t).

While the terms may be standard, not every NEMA enclosure is created equal. At every performance level, Bison ProFab NEMA enclosure products offer the extra durability and consistent manufacturing quality that comes from applying the latest in manufacturing equipment and decades of enclosure building experience.