Editorial by Industrial Quick Search

NEMA Enclosures: Types, Sizes and Applications

Contact Companies

Please fill out the following form to submit a Request for Quote to any of the following companies listed on


Get Your Company Listed on this Power Page


Introduction

This article provides comprehensive information about NEMA enclosures. You will learn how NEMA enclosures are made, and their materials of construction as well as applications, advantages, and drawbacks.

Read further to answer questions like:

  • What does NEMA mean?
  • How do NEMA enclosures protect electrical and electronic devices?
  • What‘s the difference between NEMA and ingress protection (IP) ratings?
  • How do UL and NFPA standards relate to NEMA enclosures?
  • How are NEMA enclosures made and what materials are used?
  • What types and sizes of NEMA enclosures are available from leading manufacturers?
  • How do I specify NEMA enclosures when ordering or submitting an RFQ?
  • Where are NEMA enclosures used?
  • And more
NEMA Enclosure

What are NEMA Enclosures?

NEMA enclosures are specifically designed containers that protect electrical components from environmental conditions. Based on the NEMA rating, the protection offered by these enclosures includes:

  • Suitable for use in indoor, outdoor, or combined indoor and outdoor settings
  • Protection against moderately wet conditions, such as dripping water and light splashes
  • Environments where equipment is hosed down regularly or occasionally submerged in water
  • Outdoor settings exposed to snow, sleet, or ice, or industrial freezers used in food processing
  • Dusty and dirty industrial environments like factories, mining, and oil & gas industries
  • Industries that involve exposure to greases, oils, solvents, and non-corrosive coolants
  • Corrosive areas exposed to saltwater, acids, or alkaline solutions
Indoor Non-Hazardous NEMA Enclosures
Specific Applications, Indoor Nonhazardous Locations Type of Enclosure
Offers protection against: 1 2 3 11 12 13
Accidental contact with internal components X X X X X X
Protection from falling dust particles X X X X X X
Resistance to airborne dust and particles   X   X X
Drips from non-corrosive liquids and light splashes   X   X X X
Seepage of oil or coolant         X X
Spray or splash from oil/coolant           X
Resistance to corrosive substances       X    

NEMA enclosures not only protect internal equipment but also shield workers and property in the surrounding environment:

  • Explosion-proof or hazardous location NEMA enclosures can contain internal explosions from arcing or sparks, preventing ignition of volatile chemicals in dangerous areas.
  • They guard workers against injuries resulting from contact with electrical components within the enclosure.
  • Enclosures equipped with locks deter unauthorized access and tampering with electronic, communication, and electrical equipment housed inside.
Outdoor Non-Hazardous NEMA Enclosures
Specific Applications, Indoor Nonhazardous Locations Type of Enclosure
Protected against: 3 3X 3R* 3RX* 3S 3SX 4 4x 6 6P
Incidental contact with enclosed equipment X X X X X X X X X X
Rain, snow, and sleet** X X X X X X X X X X
Sleet**         X X        
Windblown dust, lint, fiber, and flying particles X X     X X X X X X
Hose-down conditions             X X X X
Corrosive agents   X   X   X   X   X
Occasional temporary immersion                 X X
Occasional prolonged immersion                   X

What Are NEMA Ratings for Enclosures

NEMA Ratings Explained: Standards for Electrical Enclosures

NEMA enclosure ratings are based on the NEMA 250 standard issued by the National Electrical Manufacturers Association (NEMA), a leading organization that develops industry standards to enhance the safety and performance of electrical enclosures and equipment for both end-users and manufacturers. Understanding NEMA ratings is crucial for electrical engineers, contractors, facilities managers, and anyone specifying or purchasing electrical enclosures for various industrial, commercial, or hazardous applications.

NEMA enclosure standards are voluntary guidelines, and are self-certified by the enclosure manufacturer; this means that third-party certification is not required under the NEMA system. The manufacturer is responsible for ensuring their products meet or exceed the relevant NEMA rating requirements to provide protection for internal electrical components and operator safety.

Given that you're relying on the supplier's claim that they have met or self-certified to NEMA enclosure standards, it's essential to purchase from a trusted, leading supplier, preferably with a strong track record in NEMA electrical enclosures and industrial sealing solutions.

An alternative is to opt for third-party testing and NEMA certification to guarantee enclosure reliability. Reputable organizations such as Underwriters Laboratory (UL), Intertek, and the Canadian Standards Association (CSA) can independently certify that NEMA-rated enclosures fully comply with the rigorous standards—offering additional assurance and peace of mind for critical applications where safety and compliance are top priorities.

A certified NEMA enclosure offers greater assurance compared to a non-certified one, especially for critical environments, high-voltage systems, or mission-critical facilities. In some cases, government, military, oil and gas, and other regulated industries require UL listed or third-party certified NEMA enclosures for the electrical boxes, panel enclosures, or control cabinets used in your design or equipment.

UL Listed NEMA Rated Enclosure

NEMA enclosure ratings are designed to specify the level of protection an enclosure provides against the intrusion of solid objects (like dust, dirt, and fibers), water (from rain, splashes, hose downs, or immersion), and corrosive substances. The NEMA 250 standard defines rigorous testing and certification processes for each protection level, often requiring precise gaskets and advanced sealing methods to maintain an effective environmental barrier.

Each NEMA rating identifies the degree of protection an enclosure offers against hazardous penetration—including the ingress of objects, particles, fine dust, water sprays, water jets, or even water immersion. Hazardous locations and electrical safety requirements are defined according to the National Fire Protection Association's NFPA 70®-2017, National Electrical Code®, covering hazardous gases, vapors, fumes, and dusts.

To choose the right NEMA electrical enclosure for your application—whether you're sourcing NEMA-rated junction boxes, control panels, pushbutton stations, or instrumentation panels—it's important to match the NEMA type to the operating environment, including temperature, humidity, presence of corrosive chemicals, weather conditions, and potential exposure to hazardous materials.

NEMA Enclosure Types and Application Groups

NEMA ratings are categorized into several groups, based on their suitability for indoor use, outdoor use, wet or corrosive environments, and hazardous locations within industrial facilities:

  • Indoor or outdoor non-hazardous location NEMA Types include types 3, 3X, 3R, 3SX, 4, 4X, 6, and 6P
  • Indoor only non-hazardous location NEMA enclosures include types 1, 2, 3, 3X, 3R, 3SX, 4, 4X, 5, 6, 6P, 12, and 13
  • Hazardous location NEMA enclosures include types 7, 8, 9, and 10, specifically engineered for explosion-proof and dust-ignition proof protection in compliance with NEC (National Electrical Code) classes and groups
  • Corrosion-resistant NEMA enclosures include types 3X, 3RX, 3SX, 4X, 6P, and 11, manufactured using stainless steel, fiberglass, or other non-corrosive materials for harsh and chemical environments

All NEMA enclosure types are designed to protect personnel from incidental contact with live or moving electrical components, thus effectively safeguarding operators or users from the risk of electric shock or electrocution.

NEMA enclosures are specifically intended for electrical equipment operating at 1000 volts or lower, typical in power distribution, automation, HVAC, OEM equipment, and building systems.

NEMA Type 1 Enclosures from Hubbell

NEMA Type 1 Enclosures

A NEMA 1 enclosure is intended for general-purpose indoor use only. As with all NEMA enclosures, it protects personnel from accidental contact with the enclosed equipment. Additionally, NEMA Type 1 enclosures shield the enclosed equipment from falling dirt, making them ideal for switchgear, wall-mounted electrical panels, breaker boxes, and general industrial controls in dry locations.

NEMA Type 2 Enclosures

A NEMA 2 enclosure is drip-tight and offers the same protection as a NEMA Type 1 enclosure, with the added benefit of shielding enclosed devices from dripping and light splashing of non-corrosive liquids. Typically equipped with drip shields, NEMA 2 enclosures are used in environments where condensation is a concern, such as laundry rooms, utility closets, and areas around air conditioners, refrigerators, and other cooling or humidification equipment commonly found in commercial buildings.

NEMA Type 3 Enclosures

A NEMA 3 enclosure is weather-resistant and suitable for both indoor and outdoor use. It safeguards personnel against accidental contact with the enclosed equipment and protects devices from falling dirt, rain, sleet, snow, and windblown dust. Additionally, NEMA 3 enclosures are designed to withstand the effects of sleet or freezing rain, which can form an external ice layer without causing damage. This robust protection makes them well-suited for outdoor junction boxes, power distribution equipment, and telecommunications or utility enclosures.

A NEMA 3X enclosure offers enhanced protection with added resistance to corrosive elements (such as salt spray), making them excellent for coastal or marine environments.

NEMA Type 3R Enclosures

A NEMA 3R enclosure includes all the protective features of a NEMA Type 3 enclosure but does not provide protection against wind-blown dust. These are commonly used for meter housings and switchgear in outdoor utility infrastructure.

NEMA Type 3R Enclosures

A NEMA 3RX enclosure offers the same protection as a NEMA 3R enclosure but with added resistance to corrosive environments, extending the lifespan of outdoor electrical enclosures subjected to moisture or chemicals.

NEMA Type 3S Enclosures

A NEMA 3S enclosure provides all the protective features of a NEMA 3 enclosure, with the added advantage that external mechanisms (handles, pushbuttons, etc.) remain operational even when covered with ice—important for critical infrastructure in cold climates.

A NEMA 3SX enclosure includes the same benefits as a NEMA 3S enclosure but also offers additional corrosion resistance for harsh weather exposure or chemical processing sites.

NEMA Type 4 Enclosures

A NEMA 4 enclosure is watertight and can be cleaned with a hose—making it suitable for washdown areas in food processing plants, chemical factories, or outdoor industrial settings. Designed for both indoor and outdoor applications, NEMA 4 enclosures protect personnel from incidental contact and safeguard equipment from falling dirt, rain, sleet, snow, windblown dust, splashing water, and hose-directed water. They are also resistant to damage from external ice formation.

A NEMA 4X enclosure offers all the protections of a NEMA 4 enclosure but includes extra resistance to corrosion. Stainless steel and non-metallic NEMA 4X enclosures are popular choices for environments exposed to saltwater, harsh cleaning agents, or corrosive chemicals—such as marine, food processing, water treatment, and pharmaceutical industries.

UL NEMA Type 4X Stainless Steel Enclosures

NEMA Type 5 Enclosures

A NEMA 5 enclosure is designed to be dust-tight and suitable for both indoor and outdoor use. These enclosures provide protection for personnel against accidental contact with the enclosed equipment and are ideal for facilities such as grain elevators, woodworking plants, or manufacturing sites that generate large volumes of dust or airborne particulates. NEMA 5 enclosures also safeguard the enclosed equipment from falling dirt, settling airborne dust, lint, fibers, and flying debris, as well as from dripping and light splashing of non-corrosive liquids.

NEMA Type 6 Enclosures

A NEMA 6 enclosure is designed to be submersible and suitable for both indoor and outdoor use. These enclosures are ideal for temporary water submersion situations, industrial washdowns, and high-humidity applications. NEMA 6 enclosures protect personnel from accidental contact, guard against falling dirt, hose-directed spray, and temporary submersion. They are also resistant to drips, sleet, or freezing rain that might form an ice layer on the enclosure.

EMI/EFI Shielded Watertight NEMA Type 6 Enclosure

NEMA Type 6P Enclosures

A NEMA 6P enclosure is engineered for continuous submersion in water—including environments such as wastewater processing, marine, irrigation controls, or underground utility vaults. In addition to this enhanced protection, a NEMA 6P enclosure offers the same safeguarding as a NEMA 6 enclosure, providing a secure, watertight barrier against the harshest environmental threats.

Diecast Aluminum NEMA 6P Enclosure

NEMA Type 7 Enclosures

A NEMA 7 enclosure is designed for indoor hazardous locations and is also known as an indoor explosion-proof enclosure. These are critical in oil refineries, chemical processing, or fueling stations where flammable gases and vapors are present. They comply with Class I Groups A, B, C, and D of the NFPA 70 National Electrical Code (NEC). These groups include environments with flammable chemicals such as acetylene, hydrogen, manufactured gas, diethyl ether, ethylene, cyclopropane, gasoline, hexane, butane, naphtha, propane, acetone, toluene, and isoprene.

These enclosures are engineered to contain any internal explosion and prevent it from causing external hazards or further explosions, making them suitable for classified hazardous locations as per OSHA and NEC requirements.

NEMA Type 8 Enclosures

A NEMA 8 enclosure is designed for use in specific indoor or outdoor hazardous locations and is also known as an outdoor explosion-proof enclosure. Like all NEMA enclosures, it protects personnel from accidental contact with the enclosed equipment. These enclosures comply with Class I Groups A, B, C, and D according to NFPA 70 and the NEC. They are typical in hazardous zones with flammable gases, such as oil and gas pipelines or chemical storage.

NEMA 8 enclosures are engineered for the toughest hazardous environments, containing internal explosions and preventing external ignition sources—often incorporating pressure-sealing or oil-immersed technologies for extra safety.

NEMA Type 9 Enclosures

NEMA 9 enclosures are dust-ignition proof and suitable for specific indoor hazardous locations. Complying with Class II Groups E, F, and G of the NEC, these enclosures are ideal for facilities dealing with combustible dusts—such as metal foundries, flour or grain processing, and coal handling plants. Unlike NEMA 8 enclosures, which immerse equipment to prevent ignition, NEMA 9 enclosures rely on rugged construction and advanced gasketing to prevent the escape and ignition of explosive dusts.

NEMA Type 10 Enclosures

A NEMA 10 enclosure is designed for hazardous mining locations—meeting the requirements of the Code of Federal Regulations 30 Part 18 (as mandated by MSHA). These enclosures protect not only against accidental electrical contact and explosions, but also address the unique safety needs of mining environments, including methane gas or coal dust hazards.

NEMA Type 11 Enclosures

A NEMA 11 enclosure addresses the protection needs for specific corrosive and chemical-rich environments. These enclosures are drip-proof and protect personnel against contact. While the NEMA 11 rating is considered obsolete, it remains a reference for certain legacy installations. Enclosures with an "X" designation indicate added resistance against corrosive chemicals, making them valuable for wastewater plants and processing facilities.

NEMA Type 12 Enclosures

NEMA 12 enclosures are built for general-purpose indoor use, often constructed without knockouts. They offer higher protection than NEMA 11 enclosures, making them ideal for indoor manufacturing, packaging, and process control panels that must remain free from dust, fiber, dripping water, oil, and coolant splashes. These enclosures help prolong the lifespan and operational reliability of industrial automation and electrical systems.

UL NEMA Type 12 Carbon Steel Enclosure

NEMA 12 enclosures protect personnel from contact and keep enclosed equipment free from dirt, dust, lint, fibers, and debris. They also provide protection against dripping water or light splashing of non-corrosive liquids, improving equipment uptime in demanding production settings.

NEMA Type 12K Enclosures

NEMA 12K enclosures are general-purpose, indoor enclosures that come with knockouts, making them suitable for applications where frequent wiring changes, retrofits, or cable routing are necessary—common in control cabinets, machinery, and factory automation systems.

NEMA Type 13 Enclosures

NEMA 13 enclosures are general-purpose indoor enclosures equipped with knockouts. They offer the same protection as NEMA 12 enclosures, with the added benefit of safeguarding against splashing and spraying of oils, lubricants, heat-treat oils, greases, metalworking fluids, and coolants. NEMA 13 enclosures are ideal for factories, workshops, or machine shops with potential for oil or coolant exposure, and where reliable industrial equipment protection is essential.

How to Choose and Specify the Right NEMA-Rated Enclosure

When evaluating NEMA enclosures for your application, consider the following factors to maximize performance, compliance, and ROI:

  • Application Environment: Assess whether the enclosure will be installed indoors or outdoors, and review factors such as exposure to water, dust, corrosive substances, or hazardous materials.
  • Material Selection: Popular choices include stainless steel enclosures, polycarbonate, fiberglass-reinforced polyester, aluminum, or powder-coated carbon steel—each offering unique resistance to corrosion, impact, and environmental hazards.
  • Cable Entry and Knockouts: Determine your need for knockouts for field wiring, future modifications, and accessory mounting.
  • UL and Third-Party Listings: For code compliance in regulated industries, select UL listed NEMA enclosures or enclosures with CSA or Intertek certification.
  • Maintenance and Cleaning: In food, beverage, or pharmaceutical applications, look for NEMA 4X enclosures that support high-pressure washdowns and resist caustic cleaning chemicals.
  • Hazardous Locations: For combustible gas or dust risks, ensure the enclosure is properly rated for hazardous locations (NEMA 7, 8, 9, or 10) and consult NEC requirements for your facility.

NEMA Ratings vs. IP Ratings: Key Differences

While NEMA ratings are primarily used in North America, international projects may reference IP (Ingress Protection) ratings under IEC 60529. Although some protection levels overlap, NEMA ratings often set additional requirements for corrosion resistance, construction, and personnel safety. Always confirm which rating is accepted or required by your project specifications or local codes.

Summary

Understanding NEMA enclosure ratings ensures safety, code compliance, and long-term reliability for electrical systems. By selecting the correct NEMA type for your application, you safeguard sensitive equipment from environmental hazards—minimizing downtime, maintenance costs, and regulatory risks. For technical datasheets, performance comparisons, or a complete line of NEMA-rated enclosures, consult with experienced enclosure suppliers or industry-standard manufacturers for guidance and support.

Additional and Specialized Enclosure Ratings

NEMA Enclosures with Specialized and Supplemental Ratings

  1. UL ratings for U.S. and c-UL ratings for Canada. Underwriters Laboratory (UL) listing for electrical safety verified through third-party testing, commonly required for industrial electrical enclosures and control panels.
  2. IEC IP (Ingress Protection) rating for international and global applications, especially in industries requiring specific protection against dust and water ingress in electrical enclosures.
  3. IECEx and European Union ATEX explosion-proof ratings for hazardous locations, ensuring that electrical cabinets and industrial enclosures are safe for environments with flammable gases, vapors, or dust.
  4. NEBS TR 63 Zone 4 seismic enclosures are suitable for earthquake-prone zone 4 regions of the U.S., supporting mission-critical network equipment during seismic activity.
  5. FCC and VDE TEMPEST level shielding requirements for electromagnetic and radio frequency interference (EMI and RFI) or electrical noise. Industrial settings often require EMI/RFI shielded enclosures to protect sensitive electronics from disruptive electromagnetic fields caused by motors, induction heaters, or industrial automation equipment.
  6. Military standards such as Mil-Std 810 and Mil-Std 901 for Navy and U.S. armed forces applications, guaranteeing ruggedized enclosures for defense environments.
  7. RoHS, REACH, and WEEE compliant enclosures are certified not to contain any toxic or hazardous elements specified by these environmental protection standards. These certifications are a requirement for manufacturing electrical enclosures for European Union customers or eco-conscious markets.

UL Ratings and c-UL Rating for NEMA Enclosures

Underwriters Laboratories (UL) develops robust electrical safety standards for enclosures deployed in the U.S. and Canada. UL ratings are recognized nationwide in the United States, while c-UL ratings address the unique regulatory standards of Canada. Unlike NEMA ratings, which can be self-declared, UL and c-UL compliance require independent, third-party verification by recognized labs such as UL, Intertek (ETL), or CSA. This certification offers added confidence in electrical enclosure quality, assuring builders, specifiers, and procurement officers that the products meet rigorous electrical safety, fire protection, and environmental reliability standards.

Leading third-party safety certifiers evaluate NEMA electrical enclosures for adherence to UL/c-UL requirements, helping you meet regulatory needs for control panels, switchgear, and custom industrial enclosure solutions.

The primary Underwriters Laboratories standards for electrical enclosure ratings are:

  1. UL 50 - Enclosures for Electrical Equipment, Non-Environmental Considerations. Specifies construction, mounting, and accessibility features.
  2. UL 50E - Enclosures for Electrical Equipment, Environmental Considerations. Addresses weather resistance, exposure to moisture or dust, and durability.
  3. UL 508A - Standard for Industrial Control Panels. Defines electrical safety standards for custom and mass-produced control panel enclosures.

These UL standards largely align with NEMA 250 (the core NEMA enclosure rating standard), but do not extend to specialized NEMA types such as 3X, 3RX, or 3SX, which are often required for harsh or corrosive environments. Electrical enclosures may bear the UL or c-UL label as evidence of certification to these standards, improving buyer confidence.

c-UL Listed NEMA Enclosure

For a c-UL listing in Canada, the following Canadian safety standards are typically mandatory:

  • C22.2 No. 14 - Industrial Control Equipment for Use in Ordinary (Non-Hazardous) Locations. Covers control panels and terminal boxes.
  • CSA Standard C22.2 No. 40 - Cut-Out, Junction, and Pull Boxes. Focused on boxes used for electrical wire and cable management.
  • CSA Standard 22.2 No. 94 - Special Purpose Enclosures. Applies to custom or non-standard electrical enclosures.

Intertek, another prominent certification body, offers the ETL, c-ETL, and us-ETL listings, recognized throughout North America for electrical safety testing and labeling. These marks advance product credibility and are valued in electrical contracting and facility engineering industries.

IEC IP Rated Enclosures

The International Electrotechnical Commission (IEC) provides standardized ingress protection (IP) ratings for electrical and electronic enclosures worldwide. IP ratings, commonly referenced in global electronics, telecommunications, and automation industries, define the degree of protection enclosures provide against environmental hazards such as dust, dirt, and water. While NEMA enclosure ratings predominate in U.S. and Canadian industrial settings, IEC IP ratings are essential for products intended for international markets or for consumer applications like IT devices, security cameras, and outdoor electronics.

IEC Ingress Protection (IP) Ratings
Ingress Protection (IP) Ratings per International Electrotechnical Commission (IEC) Standard 60529
1sts IP Number Particle or Solid Object Ingress Protection Type 2nd IP Number Liquid Ingress Protection Type
0 No Protection 0 No Protection
1 Objects over 50mm (2") 1 Vertical Falling Drops of Water
2 Objects over 12.5mm (0.5") 2 Spray up to 15° Vertical
3 Objects over 2.5mm (0.1") 3 Spray up to 60° Vertical
4 Objects over 1mm (0.04") 4 Light Spray from Any Direction
5 Limited Dust Ingress Protection 5 Light Jet Spray from Any Dirction
6 Total Dust Ingress Protection 6 Powerful Jets from Any Direction
    7 Immersion Less Than 1m (3.28")
    8 Immersion Greater 1m (3.28")
    9 High Power Jets, High Temperature

While the IEC IP rating framework provides standardized guidance for evaluating protection against both solid foreign objects and water, it is less comprehensive than the NEMA enclosure rating system. When specifying electrical or industrial enclosures, it is crucial to recognize these differences to select the proper protection for your application needs.

A specific NEMA rating may meet or exceed a given IEC IP rating for protection against particulates and moisture—but the two systems are not directly equivalent. IEC IP code focuses exclusively on ingress resistance for dust and water, while NEMA standards incorporate additional protection, including corrosion resistance, protection against oil or coolant exposure, icing, and rigorous durability testing. This makes the NEMA enclosure rating system the preferred guideline for demanding industrial, manufacturing, and outdoor equipment environments.

It is also important to note that NEMA ratings pertain to fully assembled and operational industrial enclosures, while IP code may be assigned to enclosure subsystems, housing components, or partially assembled cabinets during production.

Comparison of NEMA and IP Ratings
NEMA Type Enclosure IEC IP Closest Match
1 IP10
2 IP11
3 IP54
3R IP14
3S IP54
4 IP66
4X IP66
5 IP52
6 IP67
6P IP68
12 IP52
13 IP54

One notable difference between the NEMA and IEC IP rating systems is that the IP code lacks classifications and testing requirements for enclosures intended for hazardous locations, limiting its use for explosive or chemically aggressive environments.

IECEx and ATEX Ratings for Hazardous Locations

International certifications for hazardous area enclosures, such as IECEx and ATEX, play a vital role in industries where electrical and electronic equipment must operate safely amid flammable gases, vapors, airborne particulates, or combustible dust. The IECEx system, established by the International Electrotechnical Commission, verifies compliance with rigorous safety requirements (IEC 60079 standards) for hazardous area electrical enclosures used globally, including petrochemical, pharmaceutical, oil and gas, mining, and processing plants.

Alternatively, ATEX certifications address requirements within the European Union, complying with the EU ATEX Directive for explosion-proof enclosures and equipment. Products certified under ATEX are engineered specifically for environments where explosive atmospheres are likely to occur, such as grain handling, chemical manufacturing, and processing operations involving hazardous dusts or vapors. ATEX certification encompasses both surface and below-ground installations, including offshore rigs and automated process facilities.

Buyers seeking electrical or instrumentation enclosures for hazardous areas should prioritize enclosure manufacturers with demonstrated experience in IECEx and ATEX testing and certification for these environments.

EMI/RFI Shielding Ratings and Electromagnetic Protection

Industrial facilities, manufacturing plants, and commercial data centers are often environments with high levels of electromagnetic interference (EMI) or radio frequency interference (RFI) caused by industrial equipment such as motors, high-frequency RF transmitters, induction heaters, fluorescent lighting, and power conversion equipment. To safeguard sensitive components, such as PLCs, sensors, and automation controls within NEMA enclosures, EMI/RFI shielding is a crucial specification considered by engineers and equipment buyers.

Effective EMI/RFI shielding prevents electromagnetic emissions or signal leakage from adversely impacting equipment within a shielded enclosure. Moreover, these shielding solutions protect critical systems from external electromagnetic disturbances, ensuring reliability, security, and uninterrupted operation.

EMI/ RFI Shield Cabinet Enclosure

Standardized testing and certification for EMC (electromagnetic compatibility) is provided by numerous global agencies, including:

  • TEMPEST - (Telecommunications Electronics Materials Protected from Emanating Spurious Transmissions) – A U.S. National Security Agency and NATO specification for ensuring secure, leak-resistant enclosures.
  • FCC Part 15 - Federal Communications Commission’s rules for regulating RF emissions in the 9 kHz–3000 GHz range, applicable to most electronic enclosures.
  • NSA 94-106 Standard - U.S. National Security Agency Specification for Electromagnetic Shield Enclosures.
  • European Union VDE - Standards from the VDE Association for Electrical, Electronic & Information Technologies.
  • Mil-Std 285 - Attenuation Measurement for Shielded Enclosure Effectiveness.
  • IEEE 299-1997 - IEEE Standard Method for Measuring Effectiveness of Electromagnetic Shielding Enclosures.
  • ASTM E 1851 - Standard Test Method for Electromagnetic Shielding Effectiveness of Durable Rigid Wall Relocatable Structures.

EMI/RFI shielding typically utilizes an electrically conductive or magnetic barrier. Metal enclosures—such as those fabricated from carbon steel, stainless steel, or aluminum alloys—naturally provide strong shielding, while plastic enclosure housings require an added metallic or conductive coating to achieve adequate EMI/RFI attenuation. Engineers often specify materials with high magnetic permeability when magnetic field shielding is needed, such as certain grades of ferritic stainless steel.

Despite robust enclosure construction, EMI and RFI can penetrate through seams, covers, or access doors. Therefore, NEMA enclosures and IP-rated electrical cabinets designed for electromagnetic shielding employ specialized shielding gaskets, such as metalized polymer, conductive fabric, wire mesh, or expanded metal, to maintain full protection at all points of entry and assembly joints. Careful application of these gaskets is a key factor in meeting EMC compliance and industry standards.

NEBS Zone 4 and Seismic-Rated NEMA Enclosures

The Telcordia GR-63 CORE (NEBS) Network Equipment Building Seismic Standard determines enclosure suitability for operation in earthquake-prone regions. These standards segment the United States into seismic risk zones, with Zone 4—including California and Alaska—having the highest risk of seismic activity. Data centers, telecom sites, and mission-critical facilities located in these high-risk areas require NEBS Zone 4 NEMA enclosures or seismic-rated rack cabinets to ensure the integrity of network equipment and infrastructure when exposed to strong ground motion or shocks.

Mission-critical data and communications equipment—including NEMA rack enclosures, network cabinets, battery systems, and server racks—benefit from NEBS-compliant seismic ratings, helping organizations mitigate risk, maintain uptime, and comply with building code requirements.

For locations outside the United States, the International Building Code (IBC), formerly the Uniform Building Code (UBC), also includes seismic hazard standards, especially in designated "High Seismic Areas." However, IBC/UBC seismic testing and certification are generally less stringent and more focused on individual enclosure components than the comprehensive tests required for NEBS.

U.S. Seismic Zones

RoHS and REACH Compliant NEMA Enclosures

When selecting electrical or electronic enclosures for commercial, industrial, and institutional projects, environmental compliance is an increasingly vital factor. The European Union’s RoHS (Restriction of Hazardous Substances) and REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) directives set strict limits on the presence of toxic and hazardous substances used in manufacturing electrical cabinets, electronic housings, and device enclosures.

The RoHS directive prohibits the use of ten substances linked to harmful environmental and health effects in all electrical and electronic devices sold within the European Union, covering both standard and customized enclosure designs:

  • Restricted metallic elements: Lead (Pb), Mercury (Hg), Cadmium (Cd), Hexavalent Chromium (Cr6+)
  • Organic chemicals: Polybrominated biphenyls (PBB), Polybrominated diphenyl ethers (PBDE), Bis(2-ethylhexyl) phthalate (DEHP), Butyl benzyl phthalate (BBP), Dibutyl phthalate (DBP), Diisobutyl phthalate (DIBP)

The REACH regulation expands upon RoHS, targeting all chemicals, paints, solvents, and substances used in the construction of electronic and electrical enclosures throughout their lifecycle. Compliance requires transparency in chemical content used in production, supporting the health, safety, and sustainability goals of manufacturers and end-users. Many leading enclosure manufacturers are now certified RoHS and REACH compliant, ensuring their products are suitable for global export and eco-friendly project requirements.

Leading Manufacturers and Suppliers

    Mouse Over Company Names to see their previews

    NEMA Enclosure Types and Mounting

    In addition to the NEMA type number, NEMA enclosures can be classified in three ways:

    1. By the method employed to mount the enclosure.
    2. By the style of enclosure - generally related to the application or shape.
    3. By the construction method - modular or unibody.

    NEMA Enclosure Types - By Mounting Method

    Some enclosures are mounted to a machine or a wall in a factory, while other NEMA enclosures are freestanding or floor-mounted. The NEMA enclosure is engineered with the required mounting flanges, legs, mounting holes, or mounting brackets specific to the mounting location.

    Mounting kits might be included with the NEMA enclosure or sold as an add-on option or accessory. These kits can include leg kits, pole mounting kits, pedestals and pedestal mounting kits, fastener kits, and mounting bracket kits.

    Desktop NEMA Enclosure

    Desktop NEMA enclosures are specifically designed to be mounted on workbenches, tables, and desktops. Analytical instruments often reside in these enclosures, allowing for chemical composition analysis while safeguarding the instrumentation electronics and detectors from the wet and corrosive environments typically found in industrial, R&D, and quality control laboratories.

    Desktop Extruded Aluminum Enclosure

    DIN Rail NEMA Enclosure

    DIN rail systems are widely utilized for mounting sensors, controllers, relays, switches, and other monitoring and control components. A DIN rail NEMA enclosure is engineered to be mounted on a DIN rail, offering protection to sensors, electronics, and electrical devices that are sensitive to environmental conditions in industrial settings. DIN refers to the German standards organization, which is the German equivalent of ANSI, the U.S. national standards body.

    Drop Over NEMA Enclosures

    Drop over NEMA enclosures feature lifting eyes and an open bottom, designed to be lifted by the eyes and placed over larger electrical equipment that requires environmental protection. These enclosures are commonly used to safeguard motor control centers, drives, transformers, electrical metering units, and electrical distribution systems. Drop over enclosures can often be walk-in, ground, or pad-type enclosures.

    Floor Mount NEMA Enclosure

    Floor mount NEMA enclosures are similar to free-standing enclosures but are bolted or attached to the floor. They can be less deep compared to free-standing NEMA enclosures.

    Typically, they employ unibody construction and are designed for stand-alone applications rather than integration into a machine or system. These enclosures can be heavy and often feature lifting eyes on the top to facilitate movement without damaging the sheet metal or internal components.

    Floor-mounted enclosures usually include floor supports or legs, elevating them off the ground to provide easier cable access. Most have a wide back panel for mounting instruments, monitoring electronics, and industrial controls. The larger NEMA enclosures generally come with lifting eyes for straightforward placement or removal.

    Floor Mounted NEMA Enclosure

    Free Standing NEMA Enclosure

    Free-standing NEMA enclosures rest directly on the floor and are not bolted or anchored. They are typically formed as a single monolithic or unibody structure, although modular options are available from some suppliers. These enclosures are commonly used in stand-alone applications.

    Free-standing enclosures lack legs, floor supports, or floor support kits. They often feature a deeper base inside the enclosure door to prevent scraping against the floor. Their width and front-to-back depth are usually greater to enhance stability and prevent tipping.

    These enclosures tend to be very heavy and frequently include lifting eyes on the top to facilitate movement without damaging the sheet metal or internal components.

    Free-standing enclosures may have single or double front doors, with an optional rear door or removable rear panel. They generally include internal back and side panels for mounting various devices such as automation equipment, PLCs, drives, contactors, relays, controllers, IT equipment, or process instrumentation. Some models use DIN rails, 19” EIA rack rails, fixed frames, or swing-out frames for mounting devices.

    Free Standing NEMA Enclosure

    Handheld NEMA Enclosure

    Handheld NEMA enclosures, often integrated with pushbutton switches or joystick controllers, are used to activate devices such as winches, hydraulic presses, or robotic arms. These enclosures are smaller in size and typically have a rectangular or T-shaped design.

    Pad / Ground Mounted NEMA Enclosures

    Ground or pad-mounted NEMA enclosures are large enclosures installed on a concrete pad, commonly used in outdoor applications. These enclosures typically feature an open bottom to allow wiring or cable feeds to come up through. They are designed to house industrial controls, motor drives, power distribution equipment, and transformers.

    Pole Mounted NEMA Enclosure

    Pole-mounted NEMA enclosures are designed for installation on poles, such as those used for electrical distribution lines. These enclosures can house electrical, network, and communications equipment. Tower-mounted NEMA enclosures also fall into this category.

    Pole Mounted Enclosure

    Pedestal Mounted NEMA Enclosure

    Pedestal-mounted NEMA enclosures are designed to be installed on a pedestal that is securely anchored to the floor. These enclosures are commonly used for operator interfaces and machine control. Cables run from the pedestal-mounted NEMA enclosure down through the pedestal, through a trough enclosure or protective jacket, and finally connect to the machine tool, press, or process equipment. It is important to distinguish between pedestal-mounted enclosures and pedestal enclosures; the former refers to enclosures mounted on a pedestal, while the latter is a type of outdoor enclosure used for utility applications.

    Rack Mounted NEMA Enclosure

    Rack-mounted NEMA enclosures are designed to fit into standard 19-inch EIA racks or 24-inch racks. They may include integral or optional pull handles and rack mounting brackets for secure installation. Additionally, some rack-mounted NEMA enclosures can also be used as desktop enclosures, offering versatility in different setups.

    Desktop or Rack Mounted NEMA Enclosure

    Walk-in NEMA Enclosure

    Walk-in NEMA enclosures are extremely large enclosures, typically featuring one or two doors. They often have an open bottom but can also include a full floor. These enclosures are very heavy and generally equipped with lifting eyes for positioning over a concrete pad. They are designed to protect substantial equipment such as switchboards, switchgear, transformers, drives, industrial controls, and other power distribution systems that are too large for smaller pad-mounted enclosures or cabinets.

    Wall Mounted NEMA Enclosure

    Wall-mounted NEMA enclosures are attached to a wall or vertical surface using molded or welded brackets for secure mounting. They may include 19-inch EIA rails or back panels for mounting automation components.

    These enclosures are ideal for housing smaller electrical devices, instruments, and controllers, but they cannot accommodate as much equipment as floor-mounted or free-standing NEMA enclosures.

    Wall-mounted enclosures come in two variations:

    1. A swing-out NEMA wall mount enclosure has a hinge at the back. which provides access to the back of equipment.
    2. A fixed NEMA wall mount enclosure can only be accessed through the front door or cover.
    Wall Mounted Stainless Steel NEMA Enclosure

    NEMA Enclosure Types - By Application & Function

    NEMA Control Panel Enclosure

    NEMA control panel enclosures safeguard various control panel components, including push button switches, monitoring devices, controllers, membrane switch panels, alarms, annunciators, indicator lights, tamper sensors, and other control equipment. Specialized NEMA control panels include:

    1. Industrial Control Panels
    2. Fire Alarm Control Panels
    3. Security System Control Panels
    UL NEMA Control Panel Enclosure

    NEMA Battery Enclosure

    NEMA battery enclosures are engineered to house standard battery sizes in diverse environments, including outdoor, marine, highway, and industrial settings. They are designed to withstand exposure to dust, snow, rain, and water, and can contain leaks from acid batteries. These enclosures are commonly used with solar power systems to store energy and provide power during the night.

    Commercial NEMA Enclosure

    Commercial NEMA enclosures are tailored for use in various commercial settings, including stadiums, theaters, retail stores, malls, and office building complexes. They are often used to house controls for elevators, escalators, HVAC systems, and electrical power systems.

    Rack Mounted Enclosures for Data, IT & Telecommunications

    Data and IT NEMA Enclosure

    Data center enclosures, IT and telecommunications cabinets, fiber optic termination boxes, and network boxes can be built using NEMA enclosures. These enclosures typically house patch panels, network switches, servers, and uninterruptible power supplies (UPS).

    Consoles & Consolets NEMA Enclosure

    Console and console enclosures often feature an angled back front panel with two trapezoidal side panels. They can be mounted on the floor, pedestal, or desktop.

    These enclosures are commonly used to protect controllers, instrumentation, and industrial computers that manage machinery or process equipment.

    Types of console enclosures include pushbutton consolets, workstations, and operator consoles. Specialized versions, such as industrial computer enclosures and kiosk enclosures, are tailored for specific applications.

    Double Sloped Console for Electronics

    NEMA Disconnect Enclosure

    Electrical disconnect NEMA enclosures are designed to house disconnect switches, load break switches, and circuit breakers. These enclosures are essential for safely de-energizing electrical circuits before performing maintenance on equipment or electrical distribution systems.

    NEMA Disconnect Enclosure

    NEMA Drive / MCC Enclosure

    Drive enclosures and motor control center enclosures house motor drives, inverters, and motor controllers, providing the necessary electrical power to manage the speed and operation of AC or DC motors. For larger installations, drop-over drive enclosures offer a protective solution.

    Hazardous Location NEMA Enclosure

    NEMA enclosures designed for hazardous locations that contain volatile or combustible gases or substances are engineered to suppress internal explosions and prevent these explosions from causing external hazards.

    Hydraulic or Pneumatic Control NEMA Housing

    NEMA enclosures are also used for hydraulic and pneumatic controls, managing the activation and deactivation of cylinders, hydraulic motors, and fluid power valves. These enclosures may house electropneumatic and electrohydraulic components, along with electrical switches and control panel indicator lights.

    Additionally, NEMA enclosures are used to house pressurization and purging equipment and systems in process plants.

    Industrial NEMA Enclosure for Variable Frequency Drive

    Industrial NEMA Enclosure

    Industrial-grade NEMA enclosures are designed for use in manufacturing factories and process plant settings. Typically constructed from cold-rolled steel, galvanized steel, stainless steel, or aluminum, these enclosures are often made with heavier gauge thicknesses to ensure durability and robust protection.

    NEMA Instrument Enclosure

    NEMA instrument enclosures are designed to safeguard instrumentation such as monitors, analyzers, and data loggers used in factory settings. These instruments measure various parameters including temperature, pressure, humidity, flow, part count, force, and strain. While instrument enclosures are typically compact, larger versions are available to accommodate complex processes requiring extensive measurement and data logging.

    NEMA Junction Box Enclosure

    Junction box NEMA enclosures are used to protect wiring connections, DIN rails, and terminal wiring within an electrical distribution system. They may also house switches, outlets, or receptacles. Junction boxes, also referred to as terminal boxes or utility boxes, provide a secure and organized way to manage electrical connections.

    NEMA Message Board / Display Enclosure

    NEMA message board or display enclosures are designed to protect display screens mounted in overhead factory locations. These enclosures safeguard the screens that provide critical information to operators, technicians, and engineers about process conditions, productivity levels, and hazardous situations. Common applications include message boards for Vorne systems, which are housed in these protective enclosures.

    NEMA Enclosure for Vorne Message Display

    NEMA Metering Cabinet

    Metering cabinets are designed to house transformers and electrical metering equipment, typically located outdoors and exposed to various weather conditions such as rain, snow, and ice. To ensure protection, these cabinets are equipped with NEMA-rated enclosures. They are also referred to as utility measurement cabinets.

    Miniature NEMA Case

    Miniature NEMA cases are compact enclosures designed to house smaller components such as sensors, transducers, sensor transmitters, instruments, and printed circuit boards.

    These cases are often integrated into or form part of a product design, serving as the housing for handheld instruments or monitors intended for operation in dusty, wet, or hazardous environments. A miniature NEMA case is essentially a scaled-down version of an instrument enclosure.

    ⅛ DIN Extruded Aluminum Case

    Operator Interface Enclosure

    Enclosure designed to contain operator interface devices such as electronics, controls, pushbuttons, joysticks, switches, membrane switch panels, and displays.

    Operator interface equipment enables an operator to monitor and control manufacturing machinery, process equipment, and other plant systems. Human-machine interface (HMI) devices are comparable products used for interacting with machines and processes.

    Types of operator interface NEMA enclosures include console enclosures, pushbutton enclosures, PC enclosures, and handheld enclosures.

    Pushbutton, Console and Operator Interface NEMA Enclosures

    NEMA PC Enclosure

    NEMA PC enclosures are designed to house and protect industrial computers, computer boards, monitors, keyboards, and peripherals. They are commonly used for process and machine control applications.

    Pushbutton NEMA Enclosure

    Pushbutton NEMA enclosures feature front panels with multiple holes designed to accommodate push button switches. Custom gaskets or seals are often required to ensure these openings are properly sealed.

    NEMA Rack Enclosure / Cabinet

    NEMA rack enclosures are designed with 19-inch EIA rails to mount standard network and communications equipment, including servers, routers, UPS systems, network switches, and audio-video equipment. They are also used in cleanroom and laboratory environments.

    Sanitary / Hygienic NEMA Enclosure

    Hygienic or sanitary NEMA enclosures are designed for use in industries such as food and beverage, pharmaceuticals, hospitals, dental, and medical device manufacturing, where washdown capabilities are crucial for maintaining clean and disinfected equipment. These enclosures are typically made from stainless steel and feature removable seals for thorough cleaning and disinfection. NEMA Type 4 or 4X watertight enclosures, which are suitable for washdown with high-pressure water, are often the best choice for these applications.

    Solar Energy NEMA Enclosures

    Solar energy NEMA enclosures are used to house components such as wiring, wiring terminals, and charge controllers. Batteries for solar energy systems are often housed in separate NEMA battery enclosures for added protection and organization.

    Traffic Control NEMA Enclosures

    Traffic control NEMA enclosures safeguard components used in rail, mass transit, and street signal systems, including timing clocks, lightning arrestors, circuit breakers, and disconnect switches. They ensure the protection of critical controls and equipment against environmental factors.

    NEMA Tamper / Vandal Proof Enclosure

    NEMA tamper and vandal-proof enclosures are designed with locks or lockable latches to deter tampering and unauthorized access. They may also include tamper sensors that detect when a control or security panel enclosure is opened without proper authorization, adding an extra layer of security.

    5052 Aluminum NEMA Wiring Trough

    NEMA Wireways and Wiring Troughs

    NEMA wireways and wiring trough enclosures are used to organize and protect cables and wiring. They shield wiring runs from environmental hazards such as dirt, dust, oil, dripping water, rain, sleet, and snow.

    Functioning similarly to ductwork for wires and cables, these enclosures come in various shapes and sizes. In addition to straight sections, they are available with several connectors and adapters, including:

    • Elbows - 90 and 45 degree
    • Tees
    • Crosses
    • Splices
    • U-connectors
    • Side couplings

    Wireways can be regarded as a type of raceway or enclosed conduit. Wiring troughs typically come with two end caps or closed ends, whereas wireways have open flanged ends. Wiring troughs may feature knockouts along the sides or on the closed ends.

    Wireways come in three distinct types:

    1. Lay-in wireways - Have a cover that lifts off or swings open allowing cabling to be laid in.
    2. Pull-through wireways - Cabling is pulled or pushed through.
    3. Cable trough - Wireway with any cover, just a trough.

    Wireways and wiring troughs are also referred to as conduits, gutters, raceways, wiring ducts, and wire ducts.

    Modular Electronic Console Enclosure Internal Frame Structure

    NEMA Enclosure Types - By Construction Method

    Modular NEMA Enclosure

    Modular enclosures are typically designed with a frame to which the side, front, top, bottom, and back panels are attached. These external panels can be made from sheet metal, extrusions, or roll-formed parts. The frame is usually mounted to the floor with leveling feet or a base plinth.

    This modular design provides enclosure manufacturers, system integrators, OEMs, and manufacturing facilities with greater flexibility to customize and adapt configurations for specific applications.

    Modular enclosures are often used for IT equipment cabinets, featuring 19" EIA mounting rails for IT components. Internal side and back panels are utilized to mount various automation equipment, including monitors, relays, data acquisition units, and controllers.

    Monolithic / Unibody NEMA Enclosure

    Monolithic or unibody enclosures are constructed as a single solid structure, often made from formed sheets welded together, molded fiberglass, or die-cast aluminum. For larger enclosures, this construction type offers enhanced structural load support compared to modular or bolted assemblies. However, customization and modifications may be more challenging to implement compared to modular enclosures.

    NEMA Enclosure Materials and Construction

    What materials are used and how are NEMA enclosures made?

    The level of protection and durability an enclosure provides is significantly influenced by its material composition. Enclosures are typically made from materials categorized as metals or polymers, including coated steel, galvanized steel, stainless steel, aluminum, fiberglass, and plastic.

    Metals generally offer better conductivity for both heat and electricity compared to other materials. This electrical conductivity is advantageous for grounding the enclosure.

    Metal enclosures can protect electronic and electrical devices from electrical and magnetic fields, as well as electromagnetic interference (EMI) and radio frequency interference (RFI). However, gaps in doors and openings for cables can still allow noise to penetrate.

    Standard NEMA enclosure shapes include rectangular and square boxes, while less common shapes feature round boxes, T-shaped enclosures, and angled front boxes. T-shaped enclosures typically have a lower handle attached to a square or rectangular box.

    Key components of an enclosure are the enclosure box, cover, bezel, legs or stand, and mounting hardware.

    Stainless Steel Sheet Formed and Punched to Form NEMA Freestanding Enclosure

    NEMA Metal Enclosure Manufacturing

    NEMA Metal Enclosure Part Fabrication

    Steel, aluminum, stainless steel, and other metallic NEMA enclosures and their parts are commonly fabricated by bending, forming, drawing, roll forming, and stamping sheet metal into the desired shapes.

    Aluminum sheet metal, due to its high ductility and formability, is particularly easy to work with when creating box or enclosure shapes. In addition to forming, aluminum enclosures can also be produced through die casting and extrusion processes.

    Compared to steel, aluminum is softer and can be cut or machined more easily. Its softness allows even woodworking carbide saw blades to cut through it effectively.

    NEMA Metal Enclosures

    Metals of Construction

    Steel Enclosures

    Steel is a popular choice for forming enclosures due to its strength and malleability. As a commercial iron alloy containing carbon, steel comes in various grades. Low carbon steels like 1020 or 1010 are softer and easier to form, making them ideal for many applications. Compared to plastic, steel or stainless steel enclosures offer significantly higher impact resistance.

    In a busy factory setting, heavy-walled coated steel or stainless steel enclosures are more durable and resistant to denting and impacts than aluminum or plastic enclosures. While a steel enclosure might sustain a dent from a forklift, a similar impact could shatter a fiberglass or plastic enclosure.

    Steel lacks the inherent corrosion resistance found in plastics and stainless steels. Therefore, steel enclosures typically require additional protective coatings, such as electroplating, zinc galvanization, or powder coating. These coatings not only enhance durability but also offer the flexibility to match or provide colors for new product designs and older equipment refurbishments.

    Stainless Steel Enclosures

    Stainless steel is preferred over standard steel in environments where corrosion resistance is crucial. It offers both chemical and corrosion resistance, and can handle relatively high-pressure conditions.

    The most common grades for stainless steel enclosures are 304 and 316 austenitic stainless steels. Among these, 316 stainless steel provides superior resistance to pitting corrosion in chloride and saltwater environments. Additionally, 304L and 316L stainless steels are low carbon variants designed to maintain their corrosion resistance after welding.

    In some applications, such as shielded NEMA cabinets for telecommunications and IT, 400 series ferritic stainless steels are used. These steels are magnetic and highly formable, though they are not as corrosion-resistant as the 300 series stainless steels.

    Although stainless steel is more expensive than aluminum or standard steel, it is virtually maintenance-free. Unlike other metals, stainless steel does not require coatings that need to be stripped and reapplied. In fact, applying a coating to stainless steel can actually impair its corrosion resistance.

    Stainless Steel Enclosure

    Aluminum Enclosures

    Aluminum, while generally more expensive than steel, offers several superior properties. Its lower density makes it lighter than steel or stainless steel, which can be advantageous for enclosures used in airplanes, spacecraft, or vehicles where weight reduction is critical.

    Aluminum also boasts higher electrical and thermal conductivity compared to steel. This higher thermal conductivity can aid in managing heat dissipation from the joule heating of enclosed electrical or electronic components. To enhance heat removal, aluminum enclosures can be manufactured with extruded fins.

    Although aluminum provides better oxidation resistance than steel, it still requires anodizing or protective coatings to withstand harsh environments such as ocean salt sprays or chemical plants.

    Extruded Aluminum Case Enclosure

    A 316 stainless steel enclosure can cost nearly twice as much as a coated steel enclosure of the same size, making it a choice only for industrial environments where its superior corrosion resistance is necessary. In comparison, 304 stainless steel is about 50% more expensive than coated steel enclosures. Aluminum, while more costly per pound than steel, has a density of 2.7 g/cm³, which is only 34% of steel's density of 7.8 g/cm³. Consequently, aluminum typically carries a premium of about 20% over coated steel. These cost estimates are based on prices listed by a leading supplier.

    NEMA Enclosure Material Cost Impact

    NEMA Plastic and Fiberglass Enclosure Manufacturing

    Plastic or fiberglass NEMA enclosures are typically manufactured using various molding processes. Thermoplastic resin enclosures can be produced through injection molding, extrusion, and thermoforming, with common materials including PVC, ABS, and polycarbonate resins.

    Plastics and fiberglass are easily machined to create cutouts or openings for wiring, switches, and operator interface controls.

    The fiberglass fabrication process depends on the type of glass fiber used, such as short or long fibers, nonwoven glass mat, or woven fiberglass cloth.

    Thermoset resin-based fiberglass enclosures can be made from sheet molding compounds (SMCs) or bulk molding compounds (BMCs), typically through compression or injection-compression molding. Reaction injection molding (RIM) is also used for molding thermoset resins, such as polyurethanes, into enclosures.

    Resin transfer molding (RTM) is another method used for creating thermoset fiberglass enclosures. In this process, fiberglass mat or woven fabric is placed in a mold, and a thermoset resin mixed with a hardener or catalyst is then injected into the mold.

    The SCRIMP (Seemann Composites Resin Infusion Molding Process) is an RTM method that uses vacuum pressure to pull liquid resin into a mold containing fiberglass reinforcement. SCRIMP is known for producing high-quality fiberglass parts with minimal VOC emissions.

    Large custom enclosures or even industrial shelters are fabricated with manual lay-up molding. In the manual lay-up process, fiberglass cloth or nonwoven mats are laid into a mold. Thermosets are poured or sprayed onto the fiberglass. Rollers and squeegees are used to “wet out” the fiberglass or force the resin into the fibers, remove trapped air, and wipe away excess resin.

    Pultrusion processes are utilized to create long channel shapes or ribs in larger sheets, which can be particularly useful for fabricating NEMA wireway enclosures. In this process, plastics are reinforced with long strands of fiberglass in a continuous, extrusion-like method, resulting in strong, durable shapes.

    Plastic and fiberglass enclosures can be pigmented to match specific colors, whether for new product designs or refurbishing older equipment. Additionally, coatings can be applied to these enclosures to enhance their environmental resistance, improve UV stability and weatherability, and achieve specific colors suited to particular applications.

    NEMA Plastic Enclosures – Materials of Construction

    Polymer-based materials, such as plastic or fiberglass, are nonmetallic and exhibit a wide range of properties depending on the specific fillers, reinforcements, and additives used in their compounding formulations. These materials can be customized to meet specific performance requirements, making them versatile options for various applications. Common trade names for these polymer-based materials include Cycolac® (GE Plastics), Lustran® (Bayer), and Novodur® (Bayer).

    ABS Enclosures

    Acrylonitrile-butadiene-styrene (ABS) is a durable, rigid, and cost-effective thermoplastic terpolymer known for its excellent chemical resistance and dimensional stability.

    ABS achieves strong impact resistance through a “rubber toughened” structure, where small rubbery butadiene spheres are dispersed within a rigid plastic matrix. This impact-resistant ABS is commonly used in products like hard hats, automotive bumpers, and golf club heads.

    Fiberglass / FRP Enclosures

    Fiberglass or fiberglass reinforced plastic (FRP) is a robust, durable polymer that offers enhanced resistance to many caustics and higher temperatures compared to standard plastics. However, fiberglass is not completely resistant to environmental degradation. Over time, fiberglass enclosures may experience yellowing, discoloration, gloss reduction, fiberglass bloom, and blistering.

    Fiberglass generally exhibits less shrinkage during molding and offers better dimensional stability compared to certain molded plastics.

    As a composite material, fiberglass consists of reinforcing glass fibers embedded within a plastic matrix. The glass fibers used can be short or long strands, a nonwoven glass mat, or a woven fiberglass cloth.

    The most commonly used thermoset resins for fiberglass include polyester and epoxy.

    Plastic Enclosures

    Polycarbonate Enclosures

    Polycarbonate (PC) is an amorphous material known for its outstanding impact strength, clarity, and optical properties. Some common brand names for polycarbonate include Caliber® (Dow), Lexan® (SABIC), Makrofol®, and Makrolon® (Bayer). Clear polycarbonate windows boast 200 times the impact strength of glass windows.

    Polycarbonate is exceptionally tough and possesses excellent mechanical properties, making it suitable for molding with tight tolerances. However, it can be vulnerable to attack by solvents and certain chemicals. The weatherability of polycarbonate is generally moderate, but it can be improved with the addition of UV inhibitors and protective coatings.

    Polypropylene Enclosures

    Polypropylene is a thermoplastic known for its exceptional resistance to many chemicals, making it a popular choice for chemical laboratory bottles and labware. Due to its chemical resistance and durability, polypropylene is often used to fabricate enclosure covers, bezels, small junction boxes, and handheld enclosures.

    Polystyrene Enclosures

    Polystyrene is a low-cost thermoplastic that is generally more brittle compared to tougher polymers like polycarbonate or polyamides (Nylon). Despite its brittleness, polystyrene is often used to fabricate enclosure covers, bezels, small junction boxes, and handheld enclosures due to its affordability.

    PVC Enclosures

    Polystyrene is a low-cost thermoplastic that is generally more brittle compared to tougher polymers like polycarbonate or polyamides (Nylon). Despite its brittleness, polystyrene is often used to fabricate enclosure covers, bezels, small junction boxes, and handheld enclosures due to its affordability.

    NEMA Enclosure Assembly Process

    Enclosure components are typically assembled and joined using fasteners, welds, or, less commonly, adhesives. An enclosure that is fastened together is referred to as a modular enclosure. Modular enclosures offer greater flexibility for customization by allowing the mixing and matching of different modular components.

    Fasteners enable disassembly for repairs or part replacements; however, they can become loose due to vibration or movement commonly found in industrial environments. Additional sealing washers might be necessary to meet specific NEMA or IP ratings.

    Welded enclosures, on the other hand, are more secure against loosening during operation. Welds provide a leak-tight seal, which can eliminate the need for extra seals, gaskets, or sealants in a NEMA enclosure.

    A monolithic or unibody enclosure is made from a single, solid piece of material, whether through aluminum die casting, plastic injection molding, or welding of formed sheet metal. While repair or replacement of damaged components in a welded assembly can be more challenging, monolithic or unibody enclosures tend to be sturdier and have fewer gasketed gaps, reducing the chance of ingress.

    Fasteners and Mounting Feet for NEMA Enclosure Assembly

    NEMA Enclosure Features and Customization Options

    NEMA Enclosure Parts, Accessories, and Customization Options

    Although a NEMA enclosure might appear as a basic metal or plastic box, each enclosure can be customized with specific panel cutouts, coatings, and accessory parts. Customizing metal NEMA enclosures generally requires less tooling investment compared to plastic NEMA enclosures, which is an important factor to consider in the overall cost and customization process.

    Custom Electrical Enclosure

    Custom Coatings and Printing

    Specialized custom coatings and printing can be applied to NEMA enclosures to enhance their appearance and functionality for specific designs and applications.

    • Plastic NEMA enclosures may need additional EMI or RFI coatings or shielding to block internal electronics from the effects of external EM and RF fields and interference.
    • Steel NEMA enclosures require a corrosion protective coating such as a wet sprayed-on industrial paint or powder coating.
    • A very common NEMA enclosure coating is an ANSI 61 gray polyester powder coating, which is engineered to withstand outdoor weathering and exposure.
    • Flame retardant and intumescent coatings can be applied to enclosures to reduce the damage from flames or fires.
    • Silkscreen printing, pad printing, or laser marking can apply labeling, logos, or graphics.

    Openings for Wire and Cable Connections

    Openings must be created in NEMA enclosures to provide electrical power and facilitate data transmission for housed devices. Data signals need to be routed to and from electronic devices, monitors, process controllers, data acquisition modules, and other components inside the enclosure.

    Power cabling from motor drives, contactors, transformers, and relays must pass through the enclosure walls to connect with motors, heaters, pumps, machine tools, lasers, or other equipment being monitored and controlled.

    The configurations of these openings can vary widely, depending on the specific requirements of the application:

    • Through holes or cutouts punched or drilled clean through the NEMA enclosure wall
    • Knockouts or holes partially cut with connected tabs, which can be easily snapped off. Knockouts are typically circular in shapes and common on junction box NEMA enclosures.
    • Gland plates - removable panels to allow wiring and cabling without drilling holes
    • Feedthroughs
    NEMA Enclosure Windows, Gland Plates, and Doors

    Doors, Covers, and Windows

    NEMA enclosures feature doors and covers designed to work with seals or gaskets to prevent the ingress of dust, water, and other contaminants. Leading manufacturers offer a variety of covers and doors to meet diverse needs:

    • Clear covers or doors
    • Solid or opaque covers and doors
    • Removable and reversible doors
    • Cover or door with window in bezel
    • Cover with pushbutton holes
    • Hinged Covers or Doors
    • Screw-on or bolted-on Cover
    • Liftoff covers
    • ¼ Turn latch doors and covers
    • Door or covers with clamps around three or four sides
    • 3 point latch doors and covers
    • Doors or covers with padlock hasp and staple
    • Door chain
    • Door locks
    • Door handles
    Clamp, ¼ Turn Latch, and 3 Point Latch Doors

    Gaskets and Seals

    The gaskets and seals used in a NEMA enclosure play a crucial role in ensuring protection against water, oil, dust, and dirt ingress. The three main types of gaskets or seals include:

    • Seamless, formed-in-place gaskets such as urethane elastomer foams
    • Pressure-sensitive adhesive (PSA) or PSA tape bonded strip seals - with a seam
    • Seamless molded or die cut gaskets - higher availability on small enclosures
    • Seamless, removable seals - no bond or adhesive for sanitary enclosures

    Device Mounting Parts

    NEMA enclosures can include additional components to facilitate the internal mounting of electronics and electrical equipment. Key components for mounting devices inside a NEMA enclosure include:

    • Inner panels - side panel and back panels for mounting devices
    • Door bars for mounting inside cover or door
    • DIN rails
    • 19" rack rails
    • Swing out frames
    • Internal frames and brackets
    • Internal shelves
    • Dividers
    • Wiring management features
    NEMA Enclosure Thermal Management Devices

    Thermal Management

    NEMA enclosures may benefit from thermal management to ensure that temperatures within the enclosure remain within a range where electronics and electrical components can function properly.

    A NEMA enclosure can be designed to allow enclosed devices to operate efficiently even in frigid, outdoor settings. In some cases, the enclosure may be encased in ice. For low-temperature applications, insulation or an internal heater might be beneficial.

    In environments such as investment metal casting foundries, forges, heat treating operations, glass melting furnaces, primary metal furnaces, and oil refineries, elevated temperatures may be present. In these scenarios, drives, transformers, and process controllers housed in NEMA enclosures might require fans, air conditioning, or other cooling solutions to maintain instrumentation within allowable operating ranges.

    Some thermal management accessories or options can include:

    • Fans and vents
    • Enclosure air conditioners
    • Fans and vents
    • Heat Dissipation Fins
    • Internal heaters
    • Insulation
    • Thermostats and temperature controllers

    Additional enclosure parts include:

    • Mounting panels - internal back panels or side panels for mounting devices
    • Legs, pedestals, and bases or plinth panels
    • Locks, latches, handles
    • Internal lighting, windows,
    • Switches, membrane switch panels,
    • Sun shields, drip shields, roofs, and slope tops
    • Grounding straps and grounding studs
    • Vents, fans, and fan Covers

    Specifying and Ordering NEMA Enclosures

    When ordering a NEMA enclosure, the NEMA rating number is the primary specification to consider. This rating indicates the level of protection the enclosure provides against environmental factors.

    The dimensions and shape of the enclosure are also crucial specifications. The size and shape should accommodate the electrical or electronic devices to be protected. The enclosure must be large enough to allow for in-place repairs or removal for servicing.

    It is important to ensure sufficient clearance between the electrical devices and the walls of the metal NEMA enclosure. This clearance allows for proper wiring installation and helps prevent electrical shorts or ground faults to the enclosure housing.

    Additionally, consider the available space in the facility, on a machine tool, or within a piece of process equipment when determining the enclosure size.

    Another important factor is that any modifications made to the enclosure, such as adding holes or altering the door's position, can nullify its NEMA rating. These changes should be carefully considered to maintain the enclosure's protective qualities.

    Flow Chart for NEMA Rated Enclosure Selection

    NEMA enclosures typically have rectangular box shapes, but they can be custom-made in many different shapes and with many additional features.

    Application Conditions & NEMA Type Selection
    Application Environment or Conditions NEMA Enclosures Types
    Industrial - Manufacturing Floor of Factory Warehouse Indoor with dirt, dust, and dripping on corrosive liquid/water NEMA 2 - Drip Tight NEMA 12
    Industrial - Manufacturing Floor of Factory Warehouse Indoor with dirt, dust, and machinery requiring washdown or hose down with non-corrosive liquid or water NEMA 4 - Water Tight/Hose Down
    Industrial - Manufacturing Floor or process plant Using oils, lubricants, metal working fluids, & coolants NEMA 13 - Oil Tight
    Industrial - Manufacturing Floor or Process Plant, Steel & Metal Mills, Cement Plants, Ceramic Using non-combustible dust and particulates NEMA 5 - Dust Tight
    Commercial & Contractor Indoor & Outdoor - falling rain, snow, and ice main concerns NEMA 1 - General Purpose NEMA 3, 3R, 3S - Weather Resistant
    Utility Power or Gas Distribution, Cable/Telephone/Network Equipment Indoor & outdoor, non-corrosive water, rain NEMA 4 - Water Tight/Hose Down
    NEMA 12 - General Purpose
    Food & Beverages Facilities, Farm / Agricultural, Chemical Process Plants, Marine Wet indoor or outdoor, rain, ice, and corrosive liquids NEMA 4X - Water Tight (Weatherproof) wit Corrosion Protection (X)
    Ships, Chemical Plants, and Oil & Gas Refineries Indoor & outdoor NEPA flammable chemicals hazardous class locations NEMA 7 - Explosion Proof
    NEMA 8 - Oil Immersed
    Metal Mills, Metal Powder, Coke & Coal, Flour & Grain Processing Facilities Indoor NFPA combustible powder class locations NEMA 9 - Dust ignition Proof
    Mining - Underground Hazardous / Flammable Class Locations Potential for Combustible Dust or Gas NEMA 10 - MSHA Complaint

    Manufacturers typically offer a catalog of standard shapes and sizes for NEMA enclosures. However, for specialized applications with sufficient order volumes, custom shapes and sizes can be produced to meet specific requirements.

    1. What type of project are you undertaking? Is the machine, process equipment, system, or product:
      1. Being built to print - Follow specifications for the enclosure on the drawing and ask the designer or design engineer to clarify if NEMA, UL, or other rating type is unclear.
      2. A new design or under development - Considered your environment - see number 2 below and the chart below.
      3. A redesign or upgrade to existing equipment - Upgrading the enclosure on equipment being redesigned might provide a more reliable and durable machine or system. Consider your application’s conditions or environment - see chart below.
      4. A repair or refurbishment of existing equipment - Look for a manufacturer’s model number on the enclosure or equipment manual. Manufacturers can provide an equivalent product matching the specifications of a competitor’s enclosure in many cases.
      5. Being installed in a plant and requiring electrical distribution system expansion - Typically, an electrical contractor and electrical engineer will be involved in designing and implementing the modifications. Make sure they understand the operating environment (dust, oil, water, explosive hazards) in your plant.
    2. What NEMA and other ratings (UL, IEC IP, C-UL, ATEX, or IECEx) do I need for my application?
    3. What is the environment (dust, water, gases, chemical, heat, cold) where the NEMA enclosure will be located?
      1. Take a look at the field or factory environment where your design or machine will operate.
        1. Is there dust or debris?
        2. Is there dripping water, forceful spray or hose washdowns, or water immersion?
        3. Are there explosive gases, corrosive acids, or explosive airborne powders?
        4. Do I need a UL, ETL, or CSA listing to comply with the National Electrical Code?
    4. Don’t over-specify on NEMA ratings!
      1. If the NEMA enclosure is only going to be used in a dry, industrial setting, then don’t ask for a NEMA or IP rating for wet environments just to be safe.
      2. Engineers and experts at leading NEMA manufacturers can consult with you on your application and guide you on the ratings recommended or required for your application.
    5. Where are your markets or customers?
      1. If your customers are solely in the U.S., then compliance with NEMA 250 as well as UL50 and UL 508 will likely be required.
      2. If your customers are in Canada, then you will probably need your NEMA enclosures to also comply with CSA standards and c-UL.
      3. If your customers are Europe, South America, Far East, or Australia, then IEC or nationally modified IECEx will need to be met.
    6. Sizing a NEMA enclosure - What size and dimensions should I specify?
      1. The NEMA enclosure should be large enough to accommodate your electronic and electrical devices such as controllers, circuit breakers, switches, etc.
      2. The enclosure should also have enough room, so individual parts on your device can be accessed for inspection, electrical testing, repair, and replacement.
      3. Additional room within the enclosure might be needed for thermal management units such as fans or heat exchangers.
    7. Custom or Standard? - What is the best option for your design or redesign project?
      1. Catalog, Standard, or COTS (complete off the shelf)
        1. Lower cost - especially in lower volumes
        2. Ready to ship - if inventory or stock is available
        3. Replacement of damaged standard NEMA enclosure for a refurbishment project
        4. Custom
      2. NEMA enclosure engineered for your design application
      3. Accessories and option built into the enclosure design - so no retrofitting of accessories and options after purchase
      What IEC Enclosure Standards Apply Where

      Like many engineers, I tend to prefer using standard or catalog parts, assuming they are less expensive than custom options.

      In theory, catalog, standard, and COTS (Commercial Off-The-Shelf) parts are readily available and require no additional engineering.

      However, it’s important to conduct a thorough cost-benefit analysis when deciding between standard and custom parts.

      Custom Design NEMA Enclosure for Equipto Electronics

      In many cases, even catalog NEMA enclosures will need some level of customization or configuration for industrial control panels and various applications. Many NEMA enclosure suppliers offer configuration tools that let you tailor or select the necessary features and options for your specific needs.

      If accommodating a standard enclosure requires significant modifications to your design, opting for a custom NEMA enclosure might be a more suitable choice.

      Many Suppliers Have Online Configurators to Select and Tailor NEMA Enclosuresfor Your Application

      Another consideration is whether additional modifications or retrofitting will be needed for the NEMA enclosure to suit your application. You should ask yourself:

      • Will the NEMA enclosure require additional openings, thermal management, grounding straps, switches, and special mounting brackets?
      • What’s the cost for modifications in-house versus custom manufacturing at the NEMA enclosure manufacturer's facility?
      • What kind of learning curve will I and my facility need to go through?

      Leveraging the skills of the enclosure manufacturer is usually the best option for modification and customization of an enclosure.

    8. Materials of construction specifications – coated steel, stainless steel, aluminum, fiberglass, plastic. The selection of the enclosure material will depend largely on:
      1. The corrosiveness of the environment
      2. The presence of solvents or lubricant, which might attack plastics or paint
      3. Weight considerations - enclosure of aircraft
      4. Thermal characteristics to resist or dissipate heat - metals are better thermal conductors with higher use temperatures. For example, an insulated metal enclosure can withstand heat from hot castings in a foundry better than a plastic enclosure.
    NEMA Enclosures

    Conclusion

    NEMA enclosures are manufactured in a wide range of NEMA types to provide the appropriate level of protection for your application from dust to dripping or wet locations to water immersion.

    NEMA enclosures are available in a wide range of shapes, configurations, mounting styles, and NEMA ratings.

    Many NEMA enclosure manufacturers are familiar with the nuances and unique requirements of specific industry applications. They can provide products specialized for different industries.

    NEMA enclosures can be designed and built to meet additional ratings such as:

    • IEC IP rating for international applications.
    • UL ratings for U.S. and c-UL ratings for Canada.
    • IECEx explosion-proof ratings for hazardous locations
    • NEBS TR 63 seismic-rated enclosures are suitable for earthquake-prone zone 4 regions of the U.S.
    • Military standards such as Mil. Std 810 and Mil. Std 901 for Navy and U.S. armed forces applications.
    • RoHS, REACH, WEEE compliant enclosures certified not to contain any toxic or hazardous elements.
    • FCC and VDE tempest level shielding requirement for electromagnetic and radio frequency interference (EMI and RFI) or noise.
    • A NEMA enclosure can be purchased as:
    • Standard or catalog NEMA enclosure product
    • Customized catalog NEMA enclosure product with additional configurator, features, and options added to meet design needs.
    • Fully custom or bespoke NEMA enclosure product - built to print or designed by the enclosure manufacturer when standard or customized enclosure cannot meet your needs.
    • While the purchased cost of a standard enclosure cost might be less, additional costs in your design or modifications to the NEMA enclosure in-house can make custom enclosures a better option after a total cost-benefit analysis.

    Leading Manufacturers and Suppliers

      Mouse Over Company Names to see their previews

      Table of Contents

      What are NEMA Enclosures?

      What Are NEMA Ratings for Enclosures

      Additional and Specialized Enclosure Ratings

      NEMA Enclosure Types and Mounting

      NEMA Enclosure Types - By Application & Function

      NEMA Enclosure Types - By Construction Method

      NEMA Enclosure Materials and Construction

      NEMA Enclosure Features and Customization Options

      Specifying and Ordering NEMA Enclosures

      Loading Leading
      Category Companies:

      • IQS Homepage
      • All Articles
      • GET YOUR COMPANY LISTED

      Related Posts

      Electronic Enclosures

      Electronic Enclosures

      Electronic enclosures are box-like structures that are designed to protect, contain, and enclose electronic components such as switches, relays, printed circuit boards (PCB), integrated circuits, power supplies, processors, etc...

      EMI Shielding

      EMI Shielding

      EMI shielding is a technique of creating a barrier that prevents leakage of strong electromagnetic fields that can interfere with sensitive devices and signals. They can be installed to isolate the electromagnetic field source or as an enclosure of the device that needs protection...

      Metal Fabrication

      Metal Fabrication

      Precision sheet metal fabrication is a common manufacturing process where the structure of a metal workpiece is cut, bent, and assembled by machining. There are any number of operations that are performed in the creation of a finished sheet metal product...

      RF Shielding

      RF Shielding

      Radiofrequency (RF) shielding is the practice of blocking radiofrequency electromagnetic signals that cause radio frequency interference (RFI). RFI can disrupt the electrical circuits of a device from working normally...

      Steel Fabricating

      Steel Fabricating

      Secondary manufacturing processes, or fabrication, work on products from primary processes to create a metal part or structure that is suitable for end-use. In these processes, semi-finished metal products are reshaped and joined...

      © IQS Directory . All Rights Reserved.