An electrical enclosure refers to a cabinet or box that contains electrical components like switches, knobs as well as controls and the like ostensibly to offer them protection against the environment while safeguarding life and property. There are various NEMA enclosure ratings defined for various electrical enclosures.
The specification features of electrical enclosures are determined by the National Electrical Manufacturers Association (NEMA), known as NEMA Enclosure Ratings, based on a type of classification that defines environments and locations where it may be used. This includes four types of explosion proof that is designed for hazardous locations.
What is NEMA?
The National Electrical Manufacturers Association(NEMA) publishes over 600 standards, technical papers and application guide on a range of topics that relate to the safety and function of electrical products effectively helping manufacturers in the US to ensure proper function, compatibility and safety of products.
An example of this is the NEMA system of ratings for plugs and various NEMA
What are NEMA Ratings?
The term NEMA is used to refer to specified standards for electrical enclosures. NEMA standard ICS 6 classifies enclosure types based on their ability to offer protection against damage or ingress caused by dust, liquids and corrosive chemicals.
These standards are reviewed and published every five years. Generally, the standards include improvements in testing standards that manufacturers must be aware of, but do not typically have an effect on the meaning of the ratings in terms of specifying equipment for defined applications.
How are Enclosures Certified under the NEMA Enclosure Ratings System?
It is important to note that NEMA does not conduct any testing of products nor is it affiliated with UL or other testing laboratories. However, it is involved in the publishing and defining of enclosure standards as well as manufacturers voluntary compliance with standards.
Manufacturers may self-declare compliance even though others use third-party testing and certification to provide customers an objective assurance of performance of the products they buy will perform to the expectations. NEMA provides a list of testing laboratories as well as certification bodies that offer this service.
What is explosion proof?
Explosion proof enclosures refer to those purpose built electrical enclosures that are designed for places where heat or spark from electrical equipment can result into an explosion or a fire. Typically, explosion proof enclosures are not designed to withstand external explosion but to contain internal explosion as well as prevent it from spreading outside. This consequently prevents larger explosions that may put human life at risk and cause damage to property.
Classification of Explosion Proof
NEMA defines hazardous location codes on the basis of the nature of the
Beyond other classification, explosion proof enclosures also include a temperature rating, which is essentially the maximum surface temperature they can withstand before the degree of protection they offer is compromised. The ratings are centered on a 40 degree Celsius ambient temperature unless indicated otherwise.
Types of Electrical enclosures
NEMA acknowledges various types of NEMA enclosure ratings depending on the degree of protection they offer against environmental factors. These are classified into non-hazardous enclosure types and hazardous location enclosure types.
Non-hazardous location enclosure types
Type 1 enclosures:
These are general purpose enclosures defined under the standard NEMA Enclosure Ratings system intended for indoor use only, hence they provide protection against contact with live parts while keeping solid foreign objects off.
Also used for indoor application, these offer same protection level like Type 1. However, they also offer protection against water from splashes, drips etc.
Type 3R, 3RX
Other than the protection provided by Type 1 and Type 2, this enclosure has a higher water resistance degree and can be used both indoors and outdoors, as they can withstand snow, sleet, rain as well as other harsh conditions. The addition of x signifies the ability of the enclosure to withstand corrosion.
Type 3S, 3SX
These enclosures are able to resist sleet, rain and the wind-blown dust and are rated for both outdoors and indoors as they possess an external mechanism that is operational even if the enclosure is ice laden. Type 3XS also provides protection against corrosion.
Type 4, 4X
In addition to the protection provided by Type 3 enclosures, these possess the capability to prevent splashes of water from entering including hose-directed water. Some of the enclosures that can be rated as Type 4 include wall mount enclosures, junction enclosures, floor mount enclosures, disconnect enclosures as well as free-standing enclosures. Type 4X shows added corrosion resistance.
These are much more like type 2 enclosures except that they have an additional gasket that seals off the enclosure effectively preventing ingress of fibers, dust as well as lint. These enclosures are recommended for indoor use.
Type 6, 6P
Other than the protection that is offered by type 4, these enclosures have a higher water resistance making them ideal for indoors and outdoors even in locations where they may be submerged. Type 6 is capable of preventing ingress of water from temporary submersion while Type 6P is for instances of prolonged submersion.
Type 12, 12K
This is rated for indoor use only as it offers
These are general purpose enclosures intended for indoor use only as they offer the same level of protection like Type 12. In addition, they have added resistance to ingress of non-corrosive coolants and oils. They are mainly wall-mounted enclosures.
Hazardous locations enclosure Types (Explosion Proof Enclosures)
There are only four NEMA pertaining to enclosures that are rated for use in hazardous locations:
Types 7 enclosures
These are intended for use indoors inClass 1, Division 1, Group A, B, C or D hazardous locations.
Type 8 enclosures
These are enclosures for outdoor and indoor use in locations classified as Class 1, Division 1, Group A, B, C or D.
Type 9 enclosures
Designed for used in Class 2, Division 1, Group E, F or G.
Type 10 enclosures
These are built to satisfy and indoor and Health Administration requirements under part 18 or CFR under 30.
Environments containing more than one type of combustible substances will require dual or multi-rated substances. Ultimately, it is always important to ensure that the product you use has the capability to operate in the area of operation that it has been deployed. So, implementing and strictly following the NEMA enclosure ratings not only provide free-standing safety but also protects you from getting into trouble with the law.
We hope you’ve found out about various NEMA enclosure ratings and how to deploy each enclosure to ensure maximum safety in all operating conditions.