Understanding NEMA Ratings: A Beginner’s Guide
Founded in 1926, NEMA Ratings provide a standardized system for classifying the environmental protection capabilities of electrical equipment. This standard is primarily used in North America for rating enclosures. Overall, the NEMA rating system ensures that electrical equipment is suitable for specific environmental conditions and applications.
What are NEMA Ratings?
NEMA stands for the National Electrical Manufacturers Association, an organization that deals with technical standards for the manufacturing of electrical equipment. The NEMA Rating classifies the level of protection an electrical enclosure has against environmental elements.
While the NEMA organization does not actually test the equipment, their ratings define the performance criteria for enclosures intended for specific environments. So why are these ratings important for electrical equipment?
The Importance of NEMA Ratings
IT environments need to have controlled conditions of a well-managed data center when operating. For most businesses, their IT environments can be distributed across multiple data centers and edge computing locations.
However, environmental factors can lead to hazards for the IT equipment. To reduce the risk of damage and downtime, businesses need to use enclosures with an appropriate level of protection. Here are some of the following reason why NEMA Ratings are used for rating enclosures:
- Environmental Protection – NEMA ratings indicate the level of protection provided by an electrical enclosure against environmental factors such as dust, water, chemicals, and corrosion. The ratings help ensure that the equipment is suitable for the specific environment.
- Safety – Ensuring the safety of personnel and preventing accidents for enclosures is crucial. When you select the appropriate NEMA-rated enclosure, potential hazards such as electric shock or exposure to hazardous substances can be minimized or prevented.
- Equipment Performance – Depending on the electrical equipment, there are specific environmental requirements to maintain for optimal equipment performance. The ratings will help you select enclosures that provide a suitable protection against factors that could impact the temperature extremes, humidity, or excessive vibration.
- Compliance and Regulations – NEMA ratings are typically specified by regulatory agencies and industry standards. Compliance with NEMA ratings ensures that electrical installations meet the necessary requirements. This helps to reduce the risk of non-compliance and associated legal issues.
- Equipment Durability and Reliability – Electrical enclosures with appropriate NEMA ratings offer increased durability and reliability by protecting the internal components against environmental factors. This extends the lifespan of the equipment, reduces maintenance needs, and improves overall system performance.
NEMA Ratings Explained For Enclosure Types
NEMA ratings are based on the NEMA 250 standard, which specifies testing and certification processes for different types of enclosures. Below is a list of the NEMA Ratings and what type of enclosure is appropriate for the application.
| NEMA 1 | Indoor use primarily to provide a degree of protection against limited amounts of falling dirt. |
| NEMA 2 | Indoor use primarily to provide a degree of protection against limited amounts of falling water and dirt. |
| NEMA 3 | Outdoor use primarily to provide a degree of protection against rain, sleet, windblown dust and damage from external ice formation. |
| NEMA 3R | Outdoor use primarily to provide a degree of protection against rain, sleet, and damage from external ice formation. |
| NEMA 3S | Outdoor use primarily to provide a degree of protection against rain, sleet, windblown dust and to provide for operation of external mechanisms when ice-laden. |
| NEMA 4 | Indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, hose-directed water and damage from external ice formation. |
| NEMA 4X | Indoor or outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, hose-directed water, and damage from external ice formation. |
| NEMA 5 | Indoor use primarily to provide a degree of protection against settling airborne dust, falling dirt, and dripping noncorrosive liquids. |
| NEMA 6 | Indoor or outdoor use primarily to provide a degree of protection against hose-directed water, and the entry of water during occasional temporary submersion at a limited depth, and damage from external ice formation. |
| NEMA 6P | Indoor or outdoor use primarily to provide a degree of protection against hose-directed water, the entry of water during prolonged submersion at a limited depth, and damage from external ice formation. |
| NEMA 7 | Indoor use in locations classified as Class I, Division 1, Groups A, B, C or D hazardous locations as defined in the National Electric Code (NFPA 70) (Commonly referred to as explosion-proof). |
| NEMA 8 | Indoor or outdoor use in locations classified as Class I, Division 2, Groups A, B, C or D hazardous locations as defined in the National Electric Code (NFPA 70) (commonly referred to as oil-immersed). |
| NEMA 9 | Indoor use in locations classified as Class II, Division 1, Groups E, F and G hazardous locations as defined in the National Electric Code (NFPA 70) (commonly referred to as dust-ignition proof). |
| NEMA 10 | Intended to meet the applicable requirements of the Mine Safety and Health Administration (MSHA). |
| NEMA 12 | Indoor use primarily to provide a degree of protection against circulating dust, falling dirt and dripping non-corrosive liquids. |
| NEMA 12/K | Indoor use primarily to provide a degree of protection against circulating dust, falling dirt, and dripping non-corrosive liquids. |
| NEMA 13 | Indoor use primarily to provide a degree of protection against dust, spraying of water, oil, and non-corrosive coolant. |
NEMA Ratings vs IP Ratings
When selecting electrical enclosures, it’s important to consider the relevant regional standards and requirements. In North America, NEMA Ratings are commonly used in North America, while IP (Ingress Protection) Ratings are globally used.
NEMA Ratings and IP Ratings are two different systems used to classify and describe the environmental protection capabilities of electrical enclosures. Even though there are some differences, both ratings refer to the protective qualities of an enclosure.
IP (Ingress Protection) Ratings
Developed by the International Electrotechnical Commission (IEC) and widely used internationally, IP (Ingress Protection) Ratings determine the level of sealing effectiveness against the intrusion from foreign objects (tools such as a screwdriver or wire), dust, water, or accidental contact.
Firstly, IP ratings consist of two digits: the first digit represents the level of protection against solid objects, and the second digit represents the level of protection against liquids. The first digit ranges from 0 to 6, indicating the level of protection against solid objects of different sizes, from no protection (0) to protection against dust (6).
Secondly, the second digit ranges from 0 to 9, indicating the level of protection against water ingress under different conditions, from no protection (0) to protection against high-pressure water jets or steam cleaning (9).
Key Differences between NEMA Ratings and IP Ratings
In comparison to IP Ratings, NEMA Ratings provide a broader range of environmental protection specifications and covers factors beyond dust and water ingress. Such factors include corrosion, impact resistance, and oil resistance. So even though there is some correlation between NEMA ratings and IP ratings, they are not directly interchangeable, as they assess different aspects of environmental protection.
Selecting The Appropriate Enclosure
Altogether, the NEMA Rating system is specifically used for organizations to determine the level of protection an enclosure has against environmental elements. Now that you have a better understanding of NEMA Ratings, you’ll be able to classify the degree of protection that an electrical enclosure will have against non-hazardous and hazardous locations. As a result, the ratings will ultimately help you select the right type of enclosure for the required protection level.
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FAQs: NEMA Ratings
What is an electrical enclosure?
An electrical enclosure is a cabinet or box that protects electrical or electronic equipment and prevents electrical shock. Enclosures are usually made from rigid plastics or such metals as steel, stainless steel, or aluminum. These enclosures are rated to designate protection against hazardous, non-hazardous, and other specific environmental conditions.
Additionally, enclosures protect electrical equipment in diverse building, industrial, and utility applications. They may also shield equipment from electromagnetic and radio frequency interference. Here are the following types of equipment that enclosures are used to protect: circuit breakers, contactors, control panels, and switches, distribution boards and panelboards, pressurization and purging equipment/systems, telephone cabinets
What are the size specifications for NEMA enclosures?
There are no standard size specifications for NEMA enclosures. The NEMA 250 standard provides construction, testing, rating and marking requirements, but each manufacturer designs their own enclosures of any size.
