Large NEMA-Rated Enclosures
NEMA Ratings for Electrical Enclosures
NEMA (National Electrical Manufacturers Association) provides standards for use in classifying electrical enclosures and housing in North America for industrial applications. NEMA rates products protection against hazardous environmental elements like dust, water, temperature, and corrosive agents. NEMA ratings define the acceptable functionality of protective enclosures in hazardous conditions.
NEMA enclosures are classified according to their protective characteristics and assigned designated numbers and letters to represent their protection level.
1: Protection from light, dust and indirect splashing. For indoor use and normal weather conditions.
2: Similar to level 1 protection with drip-tight features.
3: Weatherproof, suitable for use outdoors with protection from precipitation and falling debris.
3R: Similar to 3 with no wind- blow protection.
3S: Similar to 3 but enclosure must work even when laden with ice.
4: Water-tight, withstand jet from a 65 GMP nozzle spray from at least 3 meters for 5 minutes.
3X, 3RX, 3SX, 4X: X represent corrosion protection in used standards.
5: Dust-tight provides dust protection using gaskets and seals or other similar features.
6, 6P: Protection from temporally immersion in water at shallow depths.
7: Certified for use in hazardous indoor conditions classified as class 1, caused by combustible elements.
8: Similar to 7 but can be used outdoors.
9: Similar to 7 but for hazardous conditions classified as class II for Group E, F and G products.
10: Meets the set mining requirements defined by the MSHA (Mine Safety and Health Administration).
11: Corrosion protection from dripping liquid and flowing gas.
13: General purpose protection against spraying water and non-corrosive fluids and dust. Also provides rust resistance and oil exclusion.
NEMA standards are not equivalent to IP ratings. NEMA standards are concerned with general functionality in hazardous conditions, while IP standards are centered around weatherproofing and protection from solids and water.
A rough equivalence comparison can be made of NEMA and IP standards:
IP20 - 1
IP22 - 2
IP55 - 3, 3X, 3S, 3SX
IP24 - 3R, 3RX
IP66 - 4, 4X
IP53 - 5
IP67 - 6
IP68 - 6P
IP54 - 12, 12K, 13