Established in 1926, NEMA, or The National Electrical Manufacturers Association, provides a forum for standardizing safety, effectiveness, and compatibility of electrical products. NEMA’s intention of standardizing electronic equipment is to grow the electronic industry as a whole and improve development of new technologies. NEMA Standards define a product, process, or procedure for electronic devices. A NEMA Rating for industrial instrumentation includes Standards for enclosures, batteries, screws, software, etc.
Unlike IP Ratings, NEMA also indicates features such as protection against external ice formation, corrosion, etc. A NEMA Standard also defines one or more of the following: nomenclature, composition, construction, dimensions, tolerances, safety, operating characteristics, performance, rating, testing, and the service for which the product is designed.
This NEMA Standard, ANSI/NEMA 250-2020 provides guidelines for products such as the construction, features, applications, marking, design tests, and field modifications for enclosures for electrical equipment for general use. It also provides standards for dust-tight enclosures installed and ready for use where permitted by NEC (National Electric Code) in Class II, Division 2; Class III, Division 1; Class III, Division 2; and Zone 22 classified / hazardous locations, nonincendive electrical equipment for use in Class I and II, Division 2, and Class III, Divisions 1 and 2, classified / hazardous locations (UL 121201). Also, this NEMA Standard covers requirements for Class I; Division 1 explosion-proof enclosures marked Type 7 and Class II; Division 1 dust-ignition-proof enclosures marked Type 9.
| Location | NEMA Standard |
| Indoor | Types 1, 2, 5, 12, 12K, 13 |
| Indoor or Outdoor | Types 3, 3R, 3S, 3X, 3RX, 3SX, 4, 4X, 6, 6P |
| Classified or Hazardous Areas | Types 7 and 9 |
| NEMA Rating | Indoor | Outdoor | Solid Ingress Protection | Water Ingress Protection | Other Protective Qualities |
| NEMA 1 | yes | no | accidental contact falling dirt | none | none |
| NEMA 2 | yes | no | accidental contact falling dirt | dripping minor splashing | none |
| NEMA 5 | yes | no | falling dirt settling airborne dust lint and fibers flyings | dripping minor splashing | none |
| NEMA 12 | yes | no | falling dirt circulating dust lint and fibers flyings | dripping minor splashing | none |
| NEMA 12K | yes | no | falling dirt circulating dust lint and fibers flyings | dripping minor splashing | pre-constructed knockouts |
| NEMA 13 | yes | no | falling dirt circulating dust lint and fibers flyings | dripping minor splashing | oil and coolant seepage (non-corrosive) |
| NEMA 3 | yes | yes | accidental contact falling dirt windblown dust | rain, sleet, snow | external ice formation |
| NEMA 3R | yes | yes | accidental contact falling dirt | rain, sleet, snow | external ice formation |
| NEMA 3S | yes | yes | accidental contact falling dirt windblown dust | rain, sleet, snow | external mechanisms must be operable when ice has formed on them |
| NEMA 3X | yes | yes | accidental contact falling dirt windblown dust | rain, sleet, snow | corrosion external ice formation |
| NEMA 3RX | yes | yes | accidental contact falling dirt | rain, sleet, snow | corrosion external ice formation |
| NEMA 3SX | yes | yes | accidental contact falling dirt windblown dust | rain, sleet, snow | corrosion external mechanisms must be operable when ice has formed on them |
| NEMA 4 | yes | yes | falling dirt windblown dust | rain, sleet, snow, splashing water, hose spray | external ice formation |
| NEMA 4X | yes | yes | windblown dust | rain, sleet, snow, splashing water, hose spray | corrosion external ice formation |
| NEMA 5 | yes | no | falling dirt settling airborne dust lint and fibers flyings | dripping minor splashing | none |
| NEMA 6 | yes | yes | falling dirt | hose spray temporary submersion at limited depth | external ice formation |
| NEMA 6P | yes | yes | falling dirt | hose spray prolonged submersion at limited depth | corrosion external ice formation |
| NEMA 7 | yes | no | Explosion Proof: Class I, Division 1, Groups A, B, C or D hazardous locations as defined in the National Electric Code (NFPA 70) | ||
| NEMA 9 | yes | no | Dust Ignition Proof: Class II, Division 1, Groups E, F and G hazardous locations as defined in the National Electric Code (NFPA 70) | ||
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