An electrical enclosure is a box or cabinet that houses electrical or electronic equipment. They are used in residential, commercial, and industrial spaces. You can also find them in the streets, on a ship, or on an airplane.  Wherever utilities run, you will see electrical enclosures protecting them from plain view.

The Three Main Objectives of Electrical Enclosures

The enclosure is the only part of the equipment visible to its users. It is meant to be pleasing to the eye, but more vital are its utilitarian requirements, which are:

To protect the equipment from the environment

Outdoor electrical cabinets are required to be water-tight to protect the equipment from precipitation and extreme temperatures. These can cause damages and malfunctions. There are also enclosures designed to withstand submergence in water. Examples are submarines and areas with potential flooding.

To protect the users from the equipment

The electrical components inside the enclosure pose the main hazard. It is the job of the box to keep people from coming quickly in contact with these components. The cabinet should endure an impact, shock, or explosion brought about by the elements inside.

To mount the equipment controls

The enclosure is used to mount switches, knobs, and displays. Manufacturing equipment is typically designed to become control stations or panels. These include relays, contactors, network switches, and HMI or human-machine interface.

Safety Ratings and Standard Classification of Enclosures

International Standards

The International Electrotechnical Commission (IEC) is a global organization that reinforces quality infrastructure and international trade in electrical and electronic goods. It classifies the Ingress Protection Rating (IP codes) of electrical enclosures.

In the US

The National Electrical Manufacturers Association (NEMA) publishes electrical and technical white papers covering millions of North American products. The NEMA enclosure type standards for various grades of electrical enclosures in industrial applications are included.

The Underwriters’ Laboratories (UL) is an independent product safety organization that develops quality and safety standards for high-voltage equipment containment and electrical enclosures. They test and evaluate components and allow manufacturers to place a certification mark on qualified products.

Federal Communication Commission (FCC) is the federal agency responsible for implementing and enforcing America’s communication laws and regulations. It regulates communications, radio, television, wire, satellite, and cable in the US. FCC certification is required for all electronic products oscillating at 9 kHz or higher.

SEI Castings’ enclosures meet NEMA 4X standards & have successfully passed IP68, UL, and FCC testing in many other applications.

Types of Electrical Enclosures

Based on the NEMA rating system, there are various electrical enclosure types and their unique application. Carefully consider which type to use before moving forward with your electrical projects.

NEMA Type 1 Electrical Enclosures

NEMA Type 1 enclosures are intended for indoor purposes. This type of cabinet is cost-effective to protect valuable equipment and prevent it from public access. It offers a basic level of protection against dust, dirt, and unintentional contact with the device.


These enclosures are made for both indoor and outdoor locations. Since they provide protection from dirt, rain, snow, and ice, they are usually used for outdoor electrical enclosures. They can house wiring and cables in areas without extreme weather conditions. However, it is noteworthy that this type of enclosure is rated to provide the lowest level of protection for outdoor purposes.


NEMA 4’s water-tight features make them suitable for outdoor purposes in areas with harsh weather conditions. These enclosures can protect the equipment against splashing and hose-directed water. They are usually utilized for outdoor wiring, power, and telecommunication systems.

With a focus on quality and excellence, SEI Castings offers a wide range of services and products to meet your specific requirements.

NEMA Type 4X Electrical Enclosures

NEMA Type 4X enclosures deliver the same protection as NEMA 4 rated enclosures but with added defense against corrosion. Water-tight and corrosion-resistant, these enclosures are best utilized in applications with excessive moisture and corrosive chemicals.

SEI Castings’ enclosures meet NEMA 4X standards and can be supplied with a powder-coated finish. The latter’s addition makes its corrosion resistance even more effective in the long run. Visit us at to learn more.


These enclosures are suitable for both indoor and outdoor use. They are common in maritime transportation, power plants, and alternative energy establishments. Waterproof electrical boxes can be applied in areas where submersion in water or flooding is expected.

NEMA Type 6P Electrical Enclosures

These cabinets offer the same shield as NEMA 6 boxes but are made to withstand prolonged submersion in water. It goes without saying that they also put an added defense against corrosion. These cabinets can house electrical devices in underground mines and remote caves.


NEMA Type 7 cabinets are designed for indoor hazardous locations. These boxes are built to bear atmospheres holding inflammable gases in the air, which may cause explosions. These explosion-proof enclosures are utilized in chemical plants and oil facilities.

NEMA Type 12 Electrical Enclosures

These enclosures are built for indoor applications to guard against dust, dirt, water drips, and other non-corrosive liquids. Typically, they are common in machining, manufacturing, and industrial applications. They offer more robust defense than Types 1 and 2 but less protective than Types 4X and 6P.

Top Materials Used for Electrical Enclosures

SEI Castings provides innovative solutions for custom metal product needs in various industries.

Electrical boxes and cabinets are usually made from rigid materials that meet the house’s conductivity, insulation, and protection of different electric equipment.

  • Stainless steel:  is a heavy material that is fire-resistant and functions well in wet environments.  They are more expensive than other materials, though.
  • Carbon steel:  are robust and cost-effective.  Unless they are powder-coated, they can be very prone to corrosion and should be avoided in coastal and humid locations.
  • Polycarbonate:  has good impact resistance and is less expensive than other materials.  They are versatile and can be used for both indoor and outdoor applications.
  • Fiberglass:  is waterproof and corrosive-resistant.  They are used in both indoor and outdoor locations.
  • Aluminum: is a highly durable material.  It is an excellent conductor of heat and electricity.  Although they are more expensive than plastic materials, they are light, non-corrosive, and withstand high temperatures.  Aluminum also offers natural RF shielding to prevent interference.

SEI Castings offer enclosures, custom castings, waveguide components, and many more.  For more information about our products and how we can customize your project requirements, you may call us at