Electrical Enclosures

At first glance, electrical enclosures may not seem all that important. However, these carefully engineered boxes play a vital role in protecting electronics in industries such as telecommunications, IT systems, and utilities, among many others.

With technology growing at such a fast pace, electrical enclosures are more important than ever. Choosing the right type of enclosure for electrical devices can save not only lives but billions of dollars in equipment and operating costs. The challenge for design engineers is knowing which enclosure is right for their unique application. Today, electrical enclosures, such as junction boxes, come in many different types which must be carefully considered before moving forward with electrical projects.

What are electrical enclosures?

An electrical enclosure is a cabinet or box that protects electrical or electronic equipment from the environment and prevents electrical shock to users. These enclosures are usually made from rigid plastics or metals such as steel, stainless steel, or aluminum.
In diverse building, industrial, and utility applications, enclosures protect electrical equipment. They may also help in shielding equipment from electromagnetic and radio frequency interference. Enclosures are often used to protect the following types of equipment:

• Circuit breakers, contactors, control panels, and switches
• Distribution boards and panel boards
• Pressurization and purging equipment and systems
• Telephone cabinets
• All enclosures must be installed in accordance with the National Electrical Code and follow all applicable local regulations.

Terminology

For some purposes, enclosures have partially punched openings (knockouts) that can be removed to accommodate cables, connectors, or conduits. Where they are small and primarily intended to conceal electrical junctions from sight or protect them from tampering, they are also known as junction boxes, street cabinets, or technically as serving area interfaces.

Materials

Electrical enclosures are usually made from rigid plastics, or metals such as steel, stainless steel, or aluminum. Steel cabinets may be painted or galvanized. Equipment that is mass-produced will generally have a customized enclosure, but standardized enclosures are made for custom-built or small production runs of equipment as well. For plastic enclosures, ABS is used for indoor applications that are not in harsh environments. Polycarbonate, glass-reinforced, and fiberglass boxes are used where stronger cabinets are required, and may additionally have a gasket to exclude dust and moisture.

Stainless Steel and Carbon Steel

Due to their high durability and corrosion resistance, carbon steel and stainless steel are both used for enclosure construction. Being the strongest of the construction options, these materials are also moisture and chemical resistant.

Aluminum

Chosen because of its lightweight, relative strength, low cost, and corrosion resistance, aluminum performs well in harsh environments. Aluminum enclosures are sturdy and capable of withstanding high impact with high malleable strength. It also acts as a shield against electromagnetic interference.

Polycarbonate

Polycarbonate used for electrical enclosures is strong but light, non-conductive, and non-magnetic. It is also resistant to corrosion and acidic environments; however, it is sensitive to abrasive cleaners. Polycarbonate is the easiest material to modify.

Fiberglass

In corrosive applications, fiberglass enclosures resist chemicals. Fiberglass material can be used over all indoor and outdoor temperature ranges and can be installed in environments that are constantly wet.

Standards

In the United States, the National Electrical Manufacturers Association (NEMA) publishes NEMA Enclosure type standards for the performance of various classes of electrical enclosures. NEMA standards cover corrosion resistance, the ability to protect from rain and submersion, and much more.

Internationally, IEC 60529 classifies the ingress protection rating (IP Codes) of enclosures.