By Jessie | 08 December 2022 | 0 Comments
What Are NEMA Ratings?
NEMA's protection standard includes explosion-proof in addition to dust-proof and water-proof (IP code only includes dust-proof and water-proof). The corresponding (close or equivalent) relationship between its enclosure protection level and IP code
National Electrical Manufacturers Association (NEMA) is an American manufacturer organization that formulates technical specifications for standardized products of electrical equipment.
NEMA standard:
NEMA 1 : It is mainly used indoors, and the protection grade to be provided is contact protection of sealed equipment and limited dust falling protection （IP 20）
2: For indoor use, the degree of protection to be provided is limited water and dust fall protection (IP 22)
3: For outdoor use, the protection grade shall be wind dust, rainfall and hail protection; The ice on the sealed box shall not damage it (IP 55)
3R: for outdoor use, the protection grade shall be rain and hail protection; The ice in the sealed box shall not damage it (IP 24)
3S: for outdoor use, the protection grade shall be wind dust, rainfall and hail protection; When there is ice accumulation, the external mechanism can still be operated (IP 55)
4: For indoor or outdoor use, the protection grade shall be water splash, wind dust and rainfall, and hose direct water spray protection; The ice on the sealed box shall not damage it (IP 66)
Specific Applications of Enclosures for Indoor Nonhazardous Locations
NEMA protection occasions
| Provides a Degree of Protection Against the Following Environmental Conditions | Type of Enclosure | ||||||||||||
| 1* | 2* | 4 | 4X | 5 | 6 | 6P | 12 | 12K | 13 | ||||
| Incidental contact with the enclosed equipment | X | X | X | X | X | X | X | X | X | X | |||
| Falling dirt | X | X | X | X | X | X | X | X | X | X | |||
| Falling liquids and light splashing | X | X | X | X | X | X | X | X | X | ||||
| Circulating dust, lint, fibers, and flyings** | X | X | X | X | X | X | X | ||||||
| Settling airborne dust, lint, fibers, and flyings** | X | X | X | X | X | X | X | X | |||||
| Hosedown and splashing water | X | X | X | X | |||||||||
| Oil and coolant seepage | X | X | X | ||||||||||
| Oil or coolant spraying and splashing | X | ||||||||||||
| Corrosive agents | X | X | |||||||||||
| Occasional temporary submersion | X | X | |||||||||||
| Occasional prolonged submersion | X | ||||||||||||
| *These enclosures may be ventilated. However, Type 1 may not provide protection against small particles of falling dirt when ventilation is provided in the enclosure top. Consult the manufacturer. **These fibers and flyings are nonhazardous materials and are not considered Class III type ignitable fibers or combustible flyings. For Class III type ignitable fibers or combustible flyings, see the National Electrical Code, Article 500. | |||||||||||||
| Provides a Degree of Protection Against the Following Environmental Conditions | Type of Enclosure | ||||||||||||
| 3 | 3R* | 3S | 4 | 4X | 6 | 6P | |||||||
| Incidental contact with the enclosed equipment | X | X | X | X | X | X | X | ||||||
| Rain, snow, and sleet** | X | X | X | X | X | X | X | ||||||
| Sleet*** | X | ||||||||||||
| Windblown dust | X | X | X | X | X | X | |||||||
| Hosedown | X | X | X | X | |||||||||
| Corrosive agents | X | X | |||||||||||
| Occasional temporary submersion | X | X | |||||||||||
| Occasional prolonged submersion | X | ||||||||||||
| *These enclosures may be ventilated. **External operating mechanisms are not required to be operable when the enclosure is ice covered. ***External operating mechanisms are operable when the enclosure is ice covered. | |||||||||||||
| Provides a Degree of Protection Against Atmospheres Typically Containing:* | Type 7 and 8 Enclosures** | Type 9 Enclosures** | Type 10 | ||||||||
| Class | A | B | C | D | E | F | G | 10 | |||
| Acetylene | I | X | |||||||||
| Hydrogen, manufactured gas | I | X | |||||||||
| Diethyl ether, ethylene, cyclopropane | I | X | |||||||||
| Gasoline, hexane, butane, naphtha, propane, acetone, toluene, isoprene | I | X | |||||||||
| Metal dust | II | X | |||||||||
| Carbon black, coal dust, coke dust | II | X | |||||||||
| Flour, starch, grain dust | II | X | |||||||||
| Fibers, flyings*** | III | X | |||||||||
| Methane with or without coal dust | MSHA | X | |||||||||
| *For complete listing, see NFPA 497M-1986, Classification of Gases, Vapors and Dusts for Electrical Equipment in Hazardous (Classified) Locations. **For Class III type ignitable fibers or combustible flyings, see the National Electrical Code, Article 500. ***Due to the characteristics of the gas, vapor, or dust, a product suitable for one Class or Group may not be suitable for another Class or Group unless so marked on the product. | |||||||||||
| NEMA Type |
Description | Requirements/Design Tests |
| 1 | Indoor use primarily to provide a degree of protection against limited amounts of falling dirt. | Rod Entry, Rust Resistance |
| 2 | Indoor use primarily to provide a degree of protection against limited amounts of falling water and dirt. | Rod Entry, Rust Resistance, Drip |
| 3 | Outdoor use primarily to provide a degree of protection against windblown dust, rain, sleet, and external ice formation. | Rain, Outdoor Dust, External Icing, Corrosion Protection |
| 3R | Outdoor use primarily to provide a degree of protection against falling rain, sleet, and external ice formation. | Rod Entry, Rain, External Icing, Corrosion Protection |
| 3S | Outdoor use primarily to provide a degree of protection against windblown dust, rain, sleet, and to provide for operation of external mechanisms when ice laden. | Rain, Outdoor Dust, External Icing, Corrosion Protection |
| 4 | Indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, hose-directed water, and external ice formation. | External Icing, Hosedown, Corrosion Protection |
| 4X | Indoor or outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, hose-directed water, and external ice formation. | External Icing, Hosedown, Corrosion Protection |
| 5 | Indoor use primarily to provide a degree of protection against settling airborne dust, falling dirt, and dripping noncorrosive liquids. | Drip, Settling Airborne Dust, Rust Resistance |
| 6 | Indoor or outdoor use primarily to provide a degree of protection against hose-directed water, and the entry of water during occasional temporary submersion at a limited depth. | Submersion, External Icing, Hosedown, Corrosion Protection |
| 6P | Indoor or outdoor use primarily to provide a degree of protection against hose-directed water, and the entry of water during prolonged submersion at a limited depth. | Air Pressure, External Icing, Hosedown, Corrosion Protection |
| 12 | Indoor use primarily to provide a degree of protection against circulating dust, falling dirt, and dripping noncorrosive liquids. | Drip, Circulating Dust, Rust Resistance |
| 12K | Indoor use (with knockouts) primarily to provide a degree of protection against circulating dust, falling dirt, and dripping noncorrosive liquids other than at knockouts. | Drip, Circulating Dust, Rust Resistance |
| 13 | Indoor use primarily to provide a degree of protection against lint, dust, spraying of water, oil, and noncorrosive coolant. | Rust Resistance, Oil Exclusion |
| 7 | Indoor use in locations classified as Class I, Groups A, B, C, and D, as defined in the National Electrical Code. | ANSI/UL 698, ANSI/UL 877, ANSI/UL 886, ANSI/UL 894 |
| 8 | Indoor or outdoor use in locations classified as Class I, Groups A, B, C, and D, as defined in the National Electrical Code. | ANSI/UL 698, ANSI/UL 877, Rain |
| 9 | Indoor use in locations classified as Class II, Groups E, F, and G, as defined in the National Electrical Code. | ANSI/UL 698, ANSI/UL 877, ANSI/UL 886, ANSI/UL 894 |
| 10 | Constructed to meet the applicable requirements of the Mine Safety and Health Administration. | In accordance with the Mine Safety and Health Administration |
| *ANSI/UL 698, Industrial Control Equipment for Use in Hazardous Locations. ANSI/UL 877, Circuit Breakers and Circuit-Breaker Enclosures for Use in Hazardous Locations, Class I, Groups A, B, C, and D, and Class II, Groups E, F, and G. ANSI/UL 886, Outlet Boxes and Fittings for Use in Hazardous Locations, Class I, Groups A, B, C, and D, and Class II, Groups E, F, and G. ANSI/UL 894, Switches for Use in Hazardous Locations, Class I, Groups A, B, C, and D, and Class II, Groups E, F, and G. | ||
Many enclosures are rated on both the NEMA and IP scales. Most MANIBOX enclosures, for instance, are tested for compliance on both standards. However, there may be times when it’s appropriate to specify an enclosure rating on one scale or the other.
Local regulations and standards are one factor to consider. NEMA ratings are more common in North America. In the rest of the world, and particularly in the EU and Asia, IP ratings are the standard choice.
Think about the intended application of your enclosure as well. In the industrial and manufacturing sectors, NEMA ratings are more common. Other sectors, such as consumer electronics, tend to use the more universal IP rating system.
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