According to NEMA, total U.S. shipments for electrical industry products exceed $100 billion annually. NEMA, or National Electrical Manufacturers Association, is made up of 400-plus member companies that manufacture a diverse set of products used in the generation, transmission, distribution, and end use of electricity as well as medical diagnostic imaging.1 They promote the safe and effective design, installation, and use of electrical and medical imaging products by developing standards and advocating technical positions that are in the best interests of the industry and the users of its products.
Why have NEMA Standards?
NEMA standards exist for everything from arc welding to wiring diagrams, and many are available free or a small fee at www.nema.org. Using standards helps companies benefit by learning from other manufacturer’s experience with similar products. Standards make products much safer and help bring innovation to market faster. NEMA standards provide a level playing ground so products can be used worldwide and give member companies a competitive edge.
This article will not cover all of the standards by any means, but here are some common standards for enclosures commonly seen in electrical and electronic devices in non-hazardous environments, when completely and properly installed, are as follows:
Type 3 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.
Type 3R Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.
Type 3S Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and for which the external mechanism(s) remain operable when ice laden.
Type 3X Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); that provides an additional level of protection against corrosion and undamaged by the external formation of ice on the enclosure.
Type 3RX Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); that will be undamaged by the external formation of ice on the enclosure that provides an additional level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure.
Type 3SX Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); that provides an additional level of protection against corrosion; and for which the external mechanism(s) remain operable when ice laden.
Type 4 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); and that will be undamaged by the external formation of ice on the enclosure.
Type 4X Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); that provides an additional level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure.
Type 6 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (hose directed water and the entry of water during occasional temporary submersion at a limited depth); and that will be undamaged by the external formation of ice on the enclosure.
Type 6P Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (hose directed water and the entry of water during prolonged submersion at a limited depth); that provides an additional level of protection against corrosion and that will be undamaged by the external formation of ice on the enclosure.
NEMA has developed charts to help consumers and manufacturers understand the various types of enclosures and what degree of protection each type provides.
IP Codes
Ingress Protection (IP) ratings are developed by the European Committee for Electro Technical Standardization (CENELEC) (NEMA IEC 60529 Degrees of Protection Provided by Enclosures - IP Code), specifying the environmental protection the enclosure provides.
The IP rating normally has two (or three) numbers:
- Protection from solid objects or materials
- Protection from liquids (water)
- Protection against mechanical impacts (commonly omitted, the third number is not a part of IEC 60529)
IP First number - Protection against solid objects
0 |
No special protection |
1 |
Protected against solid objects over 50 mm, e.g. accidental touch by persons hands. |
2 |
Protected against solid objects over 12 mm, e.g. persons fingers. |
3 |
Protected against solid objects over 2.5 mm (tools and wires). |
4 |
Protected against solid objects over 1 mm (tools, wires, and small wires). |
5 |
Protected against dust limited ingress (no harmful deposit). |
6 |
Totally protected against dust. |
IP Second number - Protection against liquids
0 |
No protection. |
1 |
Protection against vertically falling drops of water e.g. condensation. |
2 |
Protection against direct sprays of water up to 15o from the vertical. |
3 |
Protected against direct sprays of water up to 60o from the vertical. |
4 |
Protection against water sprayed from all directions - limited ingress permitted. |
5 |
Protected against low pressure jets of water from all directions - limited ingress. |
6 |
Protected against temporary flooding of water, e.g. for use on ship decks - limited ingress permitted. |
7 |
Protected against the effect of immersion between 15 cm and 1 m. |
8 |
Protects against long periods of immersion under pressure. |
Ratings are not directly equivalent between the two standards, but the following table outlines the NEMA ratings that would correspond to the performance required by an IP code. NEMA ratings also require additional product features and tests ( such as functionality under icing conditions, enclosures for hazardous areas, knock-outs for cable connections and others) not addressed by IP ratings. Here is an example of a device that has both NEMA and IP ratings
IP Code |
Min. NEMA Enclosure rating to satisfy IP Code |
IP20 |
1 |
IP54 |
3 |
IP55 |
12 |
IP65 |
4 |
IP66 |
4X |
IP67 |
6 |
IP69 |
6P |
- http://www.nema.org/About/Pages/default.aspx
- http://www.nema.org/Products/Pages/Enclosures.aspx
- http://en.wikipedia.org/wiki/IP_Code#NEMA_rating
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