Enclosure Type Rating vs. IP Rating

Electrical enclosures are rated by Type (NEMA 250 / UL 50, 50E), and/or IP rating (IEC 60529) based upon the degree of protection provided. Type ratings and IP ratings have only the following in common:

1. A degree of protection for persons from hazardous components inside the enclosure
2. A degree of protection for equipment inside the enclosure from ingress of solid foreign objects, including dust
3. A degree of protection for equipment inside the enclosure from ingress of water

NEMA 250 and UL 50, 50E Type rating documentation defines additional requirements that a Type-rated enclosure must meet. These include:
• Mechanical impact on enclosure walls
• Gasket aging and oil resistance
• Corrosion resistance
• Door and cover latching requirements
• Sheet metal gauge construction requirements (UL 50 only)
Electrical enclosures that carry only an IP rating have not been designed or tested to the additional Type-rating requirements. For this reason, and because the tests and evaluations for other characteristics are not identical, the IP ratings cannot be exactly equated with NEMA enclosure Types.

Electrical enclosures manufactured by Hoffman are tested for and carry both Type and IP ratings.    

Fluid Statics and Dynamic Comparison of Ingress Water Tests