Knowledge of NEMA 250 Standard

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Update time : 2021-12-12 13:29:25
Electricity is an indispensable part of life, but without proper protection. electrical hazards can be all too abundant.
An electrical equipment enclosure marked with caution symbol with NEMA rating via ANSI/NEMA 250-2020.

Electrical enclosures are often associated with a “NEMA rating.” These ratings derive from a standard developed by ANSI-accredited standards developing organization the National Electrical Manufacturers Association (NEMA).

NEMA: National Electrical Manufacturers Association, It is composed of hundreds of major electrical manufacturers in the United States, mainly manufacturers of various equipment and devices for power generation, transmission, distribution and power applications. They are based on engineering principle research, test records, field experience and understanding of manufacturing and installation problems. Formulate corresponding standards based on the consultation and information obtained from manufacturers, users, inspection institutions and other personnel with professional experience, Make the best design and judgment on the performance and structure of the product. The purpose is to eliminate misunderstandings between manufacturers and users of electrical products and to specify the safety of the application of these products.

IEC: International Electrotechnical Commission, IEC declares in the IP code of ied529 (BS EN 60529:1992). IP protection grade is an important index of electrical equipment safety protection. IP and other protection grade systems provide a method to classify products based on the dust-proof, waterproof and anti-collision degree of electrical equipment and packaging. This system has been recognized by most European countries.

For electrical enclosures, Europe and China generally design and verify with reference to IEC standards, but for U.S. market, the electrical enclosures also need to meet NEMA standards


Therefore, when choosing electrical enclosures, we should consider the protection rating of the enclosure.

 
NEMA
enclosure
type no.
NEMA definition IEC
enclosure
class
1 General-purpose. Protects against dust, light, and indirect splashing but is not dust-tight; primarily prevents contact with live parts; used indoors and under normal atmospheric conditions. IP10
2 Drip-tight. Similar to Type 1 but with addition of drip shields; used where condensation may be severe (as in cooling rooms and laundries). IP11
3 and 3S Weather-resistant. Protects against weather hazards such as rain and sleet; used outdoors on ship docks, in construction work, and in tunnels and subways. IP54
3R Intended for outdoor use. Provides a degree of protection against falling rain and ice formation. Meets rod entry, rain, external icing, and rust-resistance design tests. IP14
4 and 4X Watertight (weatherproof). Must exclude at least 65 GPM of water from 1-in. nozzle delivered from a distance not less than 10 ft for 5 min. Used outdoors on ship docks, in dairies, and in breweries. IP56
5 Dust-tight. Provided with gaskets or equivalent to exclude dust; used in steel mills and cement plants. IP52
6 and 6P Submersible. Design depends on specified conditions of pressure and time; submersible in water; used in quarries, mines, and manholes. IP67
7 Hazardous. For indoor use in Class I, Groups A, B, C, and D environments as defined in the NEC.  
8 Hazardous. For indoor and outdoor use in locations classified as Class I, Groups A, B, C, and D as defined in the NEC.  
9 Hazardous. For indoor and outdoor use in locations classified as Class II, Groups E, F, or G as defined in the NEC.  
10 MSHA. Meets the requirements of the Mine Safety and Health Administration, 30 CFR Part 18 (1978).  
11 General-purpose. Protects against the corrosive effects of liquids and gases. Meets drip and corrosion-resistance tests.  
12 and 12K General-purpose. Intended for indoor use, provides some protection against dust, falling dirt, and dripping noncorrosive liquids. Meets drip, dust, and rust resistance tests. IP52
13 General-purpose. Primarily used to provide protection against dust, spraying of water, oil, and noncorrosive coolants. Meets oil exclusion and rust resistance design tests. IP54


If you have questions about how to find the right IP rating or NEMA rating for an electrical enclosure, we’re always glad to help. You can email us for more information and quotes on customized enclosures.
 
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