What's the Difference Between NEMA Ratings and IP Ratings?

• share
• share
• share
• Send Page URL

Moisture and particulate matter can greatly affect pressure transmitter function and longevity. Environmental exposure to water ranges from "condensing" moisture to wash-down with water under pressure to total and permanent submersion.

WIKA manufactures a wide range of pressure transmitters to meet specific protection requirements as defined by two types of enclosure classification rating systems: National Electronic Manufacturers Association (NEMA) ratings and Ingress Protection (IP) ratings.

These systems define protection from solids and liquids entering an enclosure. An IP rating considers only protection against ingress of solid foreign objects and ingress of water, while NEMA ratings consider these and other specifics such as corrosion and construction details. It is possible to say that a NEMA type is equivalent to an IP rating, but it is not possible to say that an IP rating is equivalent to a NEMA type. The comparison of NEMA and IP enclosure ratings is only approximate. It is the responsibility of the user to verify the enclosure rating necessary for the given application.

IP ratings

The the Ingress Protection system is more commonly used in Europe but is increasingly used in the U.S. as well. Because the two systems use different test parameters, they are not directly comparable or easily converted.

NEMA Ratings

NEMA 1: General Purpose – Indoors

• Intended for general purpose indoor use, primarily to provide a degree of ingress protection against contact with the enclosed equipment or locations where unusual service conditions do not exist

NEMA 2: Drip Proof – Indoors

• Intended for general purpose indoor use, primarily to provide a degree of protection against limited amounts of falling water and dirt

NEMA 3: Dust tight, rain tight, and ice/sleet resistant – indoors/outdoors

• Intended for general purpose outdoor use, primarily to provide a degree of protection against windblown dust, rain, and sleet    
• Will be undamaged by the formation of ice on the enclosure

NEMA 3R: Rain proof and ice/sleet proof – indoors/outdoors

• Intended for general purpose outdoor use, primarily to provide a degree of protection against falling rain    
• Will be undamaged by the formation of ice on the enclosure

NEMA 3S: Dust tight, rain tight, and ice/sleet – outdoors

NEMA 4: Water tight and dust tight – indoors/outdoors

• Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment    
• Provide a degree of protection against falling dirt, rain, sleet, snow, windblown dust, splashing water, and hose-directed water    
• Will be undamaged by the external formation of ice on the enclosure

NEMA 4X: Water tight, dust tight, and corrosion resistant – indoors/outdoors

• Same as NEMA 4, with the addition of corrosion resistance    
• Enclosures and external parts attached to these enclosures shall be manufactured of American Iron and Steel Institute (AISI) Type 304 Stainless Steel, polymerics, or materials with equivalent corrosion resistance. If material other than Type 304 Stainless Steel is used, it shall be tested in accordance with 5.9 and 5.10.

NEMA 5: General purpose dust tight

• Intended for use indoors or outdoors with protection from dust provided by gaskets

NEMA 6: Submersible, water tight, dust tight, and ice/sleet resistant – indoors/outdoors

• Intended for general purpose indoor and outdoor use primarily to provide a degree of protection against the entry of water during temporary submersion at a limited depth    
• Will be undamaged by the formation of ice on the enclosure

NEMA 7: Underwriters Lab Class 1 – Groups C & D – explosion proof – indoors

• Intended for indoor use in locations classified as Class I, Groups A, B, C, or D, as defined in the National Electrical Code    
• Capable of withstanding the pressures resulting from an internal explosion of specified gases and containing such an explosion sufficiently that an explosive gas-air mixture existing in the atmosphere surrounding the enclosure will not be ignited.    
• Enclosed heat-generating devices shall not cause external surfaces to reach temperatures capable of igniting explosive gas-air mixtures in the surrounding atmosphere    
• Enclosures shall meet explosion, hydrostatic, and temperature design tests

NEMA 8: Underwriters Lab Class I – Groups C & D – explosion proof – indoors

Same as NEMA 7, except the unit is oil-immersed

NEMA 9: Underwriters Lab Class II – Groups E, F, G – indoors

• Intended for special-purpose indoor use in locations classified as hazardous (Class II, Groups E, F, and G, as defined in the National Electric Code)    
• Capable of preventing the entrance of dust    
• Enclosed heat-generating devices shall not cause external surfaces to reach temperatures capable of igniting or discoloring dust on the enclosure or igniting dust-air mixtures in the surrounding atmosphere    
• Enclosures shall meet dust penetration and temperature design tests and aging of gaskets (if used)

NEMA 11: Corrosion resistant and drip proof – oil immersed – indoors

NEMA 12: Industrial use – dust tight and drip tight – indoors

• Constructed (without knockouts) to provide a degree of protection to personnel against incidental contact with the enclosed equipment    
• Intended for industrial indoor use, primarily to provide a degree of protection against dust, falling dirt, and dripping noncorrosive liquids

NEMA 13: Oil tight and dust tight – indoors

• Intended for industrial indoor use, primarily to provide a degree of protection against dust, spraying of water, oil, and noncorrosive coolant)

* The comparison of NEMA and IP enclosure ratings is only approximate.  It is the responsibility of the user to verify the enclosure rating necessary for the given application.

IP Ratings

The IP rating system provides a means of classifying the degree of protection from solid objects and liquids afforded by electrical equipment and enclosures. The system is recognized in most European countries and is set out in a number of British and European standards. These include: Classification of Degrees of Protection Provided by Enclosures, BS (British Standards) 5490:1977; IEC (International Electrotechnical Commission) 529:1976.

The first number defines the level of protection against penetration of solid objects into the housing. The second number defines the level of protection against penetration of liquids into the housing.

Examples of items with IP ratings:

• Umbrella: IP-01 or IP-02 (depending on umbrella)    
• Chain-link fence: IP-02    
• Chicken wire: IP-20    
• Screen: IP-30    
• Kevlar cloth: IP-40    
• Tent (camping): IP-42    
• Saran wrap: IP-51    
• Bottle of wine: IP-67    
• Submarine: IP-68