NEMA RATINGS – What are NEMA ratings and why they are significant for the Electrical Industry.

NEMA is an industry body which provides standards and guidelines to the electrical manufacturing industry within Northern America. Its primary role is to create standards to which electrical components are designed and manufactured for use within various industries. Strict guidelines ensure that components are built to a satisfactory standard for their intended applications.

NEMA provides various standards which cover things such as enclosures, connectors, contacts and motors. There are multiple standards which are used to designate protection against both ingress to vital electrical components and protection from various environmental conditions. These standards are then utilized by manufacturers in the design and manufacturing stages to ultimately ensure end products are safe within specific environments.

What is NEMA?

The National Electrical Manufacturers Association (NEMA) is currently the largest trade association within the United States. NEMA was originally formed in 1926, from which it has grown substantially to provide oversight to electrical manufacturing in Northern America. The National Electrical Manufacturers Association (NEMA), has approximately 350 member companies which manufacture a range of products which are used in power generation, transmission, distribution, control and the end use of electricity. These products which are manufactured to NEMA’s standards are then used across a variety of industries including building systems, electrical infrastructure, industrial systems, lighting and utility systems. Furthermore, as the scope of NEMA’s reach is so vast, it is estimated that NEMA provides standards for more than 700 different applications. Among NEMA’s major standards are those which outline the standards for electrical enclosures, motors and magnet wire, AC plugs and receptacles.

In short NEMA sets the standards which outline how electrical components must be manufactured, what characteristics these products must posses and which environments these products will be suited to best. NEMA provides a table which outlines this level of protection offered and the environments in which they can be used in enabling quick identification for various applications.

NEMA Enclosures

NEMA sets out the standards for electrical enclosures across North America. There are 13 different types of enclosures rated from 1-13 with several sub-categories. Each enclosure has a specific rating for both the protection against access or ingress, and an additional type dependent designation with regards to environmental conditions. A typical NEMA enclosure may be rated to protect electrical equipment from environmental hazards such as water, dust, oil, or environments containing corrosive agents such as acetylene, gasoline or salt water.

Below is a list of the NEMA enclosure types. Each type specifies the characteristic of an enclosure of its assigned rating.



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.

2 – Drip-tight. Similar to Type 1 but with addition of drip shields; used where condensation may be severe (as in cooling and laundry rooms).

3 – Weather-resistant. Protects against falling dirt and windblown dust, against weather hazards such as rain, sleet and snow, and is undamaged by the formation of ice. Used outdoors on ship docks, in construction work, and in tunnels and subways.

3R – As 3, but omits protection against windblown dust.

3S – As 3, but also operable when laden with ice.

3X, 3RX, 3SX – X indicates additional corrosion protection; commonly used near salt water.

4 and 4X – Watertight. Must exclude at least 65 GPM of water from a 1 in nozzle delivered from a distance not less than 10 ft for 5 min. Used outdoors on ship docks, in dairies, in wastewater treatment plants and breweries. X (as 4X) indicates additional corrosion resistance.

5 – Dust-tight. Provided with gaskets or equivalent to exclude dust; used in steel mills and cement plants.

6 and 6P – Submersible. Design depends on specified conditions of pressure and time; submersible in water or oil; used in quarries, mines, and manholes. 6 is temporarily submersible, 6P withstands occasional prolonged submersion.

7 – Certified and labelled for use in areas with specific hazardous conditions: for indoor use in Class I, Groups A, B, C, and D environments as defined in NFPA standards such as the NEC.

8 – Certified and labeled for use in areas with specific hazardous conditions: for indoor and outdoor use in locations classified as Class I, Groups A, B, C, and D as defined in NFPA standards such as the NFPA 70.

– Certified and labelled for use in areas with specific hazardous conditions: for indoor and outdoor use in locations classified as Class II, Groups E, F, or G as defined in NFPA standards such as 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 non-corrosive liquids. Meets drip, dust, and rust resistance tests.

13 – General-purpose. Primarily used to provide protection against dust, spraying of water and non-corrosive coolants. Meets oil exclusion and rust resistance design tests.

NEMA Standards – Why they matter!

The technical standards provided by NEMA for enclosures outline both products made from metallic and non-metallic materials, intended for use with electrical equipment that need to meet an environmental requirement. These standards are vital for the design, production and distribution of electrical enclosures across North America. Consequently, the standards assist both users and manufacturers to obtain a higher level of safety. Accordingly, this reduces misunderstandings between manufacturers and purchasers, by enabling purchasers to select suitable enclosures more easily.

NEMA 6P Stainless Steel Enclosures.

Stainless Steel enclosures rated NEMA 6P such as the Subsea range and Submersible series from SLAYSON® ensure protection against the ingress of water and dust, whilst submerged in depths up to 30ft. The stainless-steel construction further ensures, protection against the corrosive environments of sea water. For more information on enclosures or ratings please visit SLAYSON®