NEMA Ratings and Enclosure Types

What are NEMA Ratings?

The National Electrical Manufacturing Association, or NEMA, is an organization that sets the technical standards for the manufacturing of electrical equipment. NEMA ratings are classifications provided by NEMA to indicate the protective quality of electrical enclosures. These ratings help to identify the usability of an enclosure in different environmental conditions, ensuring that they protect the enclosed equipment from specific hazards such as dust, water, chemicals, or mechanical impact. The ratings range from 1 to 13, with each signifying different levels of protection.

NEMA Enclosure Ingress Protection Ratings

NEMA Rating	Requirements
1	Indoor - provide a degree of protection against ingress of solid foreign objects (falling dirt).
2	Indoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt), the ingress of water (dripping and light splashing).
3	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and windblown dust, the ingress of water (rain, sleet, and snow); and the external formation of ice.
3R	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt), the ingress of water (rain, sleet, and snow); and the external formation of ice on the enclosure.
3S	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and windblown dust, the ingress of water (rain, sleet, and snow); and remain operable when ice laden.
3X	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and windblown dust), the ingress of water (rain, sleet, and snow), corrosion, and the external formation of ice.
3RX	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt), the ingress of water(rain, sleet, and snow), corrosion, the external formation of ice.
3XS	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and windblown dust), the ingress of water (rain, sleet, and snow), corrosion, and when ice laden.
4	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and windblown dust), the ingress of water (rain, sleet, snow, splashing water, and hose-directed water), and the external formation of ice.
4X	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and windblown dust), the ingress of water (rain, sleet, snow, splashing water, and hose-directed water), corrosion, and the external formation of ice.
5	Indoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and settling airborne dust, lint, fibers, and flyings), the ingress of water (dripping and light splashing).
6	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt), the ingress of water (rain, sleet, snow, hose directed water, and the entry of water during occasional temporary submersion at a limited depth), and the external formation of ice.
6P	Indoor or outdoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt), the ingress of water (rain, sleet, snow, hose directed water, and the entry of water during prolonged submersion at a limited depth), corrosion, and the external formation of ice on the enclosure.
12	Enclosures constructed (without knockouts) for indoor use - to provide a degree of protection against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings), the ingress of water (dripping and light splashing), light splashing and consequent seepage of oil and non-corrosive coolants.
12K	Enclosures constructed (with knockouts) for indoor use - to provide a degree of protection against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings, the ingress of water (dripping and light splashing); light splashing and consequent seepage of oil and non-corrosive coolants.
13	Indoor - to provide a degree of protection against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings), the ingress of water (dripping and light splashing); against spraying, splashing, and seepage of oil, and non-corrosive coolants.

UL50E & NEMA Ratings

	NEMA Type 2, 3, 3R, 3S, 4, 4X, 5, 6, & 6P Requirements:	NEMA Type 12, 12K, & 13 Requirements:
Tensile	Not less than 75% of original Tensile Strength	Not less than 75% of original Tensile Strength
Elongation	Not less than 60% of original Elongation	Not less than 60% of original Elongation
Oil Resistance	Not required for Type(s) 2, 3, 3R, 3S, 4, 4X, 5, 6, &6P	+25% swell max or -1% shrink max

Comparison of Specific Applications of Enclosures for Indoor Nonhazardous Locations

Provides a Degree of Protection Against the Following Conditions	Type of Enclosure
	1 *	2 *	4	4x	5	6	6P	12	12k	13
Access to hazardous parts	X	X	X	X	X	X	X	X	X	X
Ingress of solid foreign objects (Falling dirt)	X	X	X	X	X	X	X	X	X	X
Ingress of water (Dripping and light splshing)	-	X	X	X	X	X	X	X	X	X
Ingress of solid foreign objects (Circulating dust, lint, fibers, and flyings **)	-	-	X	X	-	X	X	X	X	X
Ingress of solid foreign objects (Settling airborne dust, lint, fibers, and flyings **)	-	-	X	X	X	X	X	X	X	X
Ingress of water (Hosedown and splashing water)	-	-	X	X	-	X	X	-	-	-
Oil and coolant seepage	-	-	-	-	-	-	-	X	X	X
Oil or coolant spraying and splashinge	-	-	-	-	-	-	-	-	-	X
Corrosive Agents	-	-	-	X	-	-	X	-	-	-
Ingress of water (Occasional temporary submersion)	-	-	-	-	-	X	X	-	-	-
Ingress of water (Occasional prolonged submersion)	-	-	-	-	-	-	X	-	-	-

The Importance of NEMA

Compliance and Regulatoins

NEMA ratings are often mandated by regulatory bodies and industry standards. Adhering to these ratings ensures electrical installations meet the necessary criteria, thereby lowering the risk of non-compliance and related legal complications.

Environmental Protection

NEMA ratings denote the degree of protection an electrical enclosure provides against environmental influences like dust, water, chemicals, and corrosion. These ratings ensure that the equipment is apt for its intended environment.

Equipment Performance

Electrical equipment has specific environmental requirements to function optimally. The NEMA ratings guide you in choosing enclosures that protect against factors such as extreme temperatures, humidity, or intense vibrations, which can affect performance.

Equipment Durability and Reliability

Using enclosures with the proper NEMA ratings enhances the durability and reliability of electrical equipment by shielding internal components from environmental stresses. This protection prolongs the equipment’s lifespan, reduces maintenance demands, and boosts overall system efficiency.

Safety

Safeguarding personnel and avoiding accidents involving enclosures is vital. Selecting a properly rated NEMA enclosure minimizes or eliminates risks like electric shock and exposure to hazardous materials.