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NEMA Ingress Protection Ratings

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Two standards govern the ingress (entry) protection (IP) of equipment enclosures. These standards use rating systems to identify an enclosure’s ability to resist external environmental influences. The two standards are:
  • International Electrotechnical Commission (IEC)
  • National Electrical Manufacturer’s Association (NEMA)
IEC ratings are based on performance criteria similar to NEMA, with different interpretations of enclosure performance. You can read about the IEC ingress protection codes here.

NEMA Ingress  Protection Ratings
NEMA indicates an equipment enclosure’s degree of protection against various materials using the numbers 1–13. The numbers cover liquid, solid, and hazardous area requirements as indicated in the table below:

NEMA Rating Description
1 General purpose enclosure
2 Drip-tight enclosure
3 Weather proof
4 Water-tight
4X Water-tight and corrosion resistant
5 Dust-tight
6 Submersible
7 Hazardous locations (Class I, Groups C and  D)
8 Hazardous locations (Class I, oil-immersed)
9 Hazardous locations (Class II, Groups E, F and G)
10 Explosion-proof (Bureau of mines 0)
11 Acid and fume resistant, oil-immersed, used indoors
12 Industrial use
13 Dust proof

Difference between NEMA enclosure Types and IEC Classifications
IEC does not specify degrees of protection against risk of explosions or conditions such as moisture or corrosive vapors. NEMA does. IEC enclosure classification designations cannot be exactly equated with NEMA enclosure type numbers. However, the table below shows general comparisons between NEMA enclosure types and IEC enclosure classifications that are similar but not exact:

NEMA Rating  IEC Protection Code
3 IP 54
4 IP 56
4X IP 56
5 IP 52
6 IP 67
12 IP 52