Accidental contact could cause bodily harm and damage the equipment itself. Without a proper shield, electromagnetic interference, or EMI, can disrupt the circuitry of many electronics and interfere with their operation.
Electrical enclosures are typically rectangular and made of aluminum, stainless steel or plastic. The size of these enclosures can range from a few inches in area, like the case of a LED flashlight, to a few hundred square feet; the largest enclosures are actually rooms.
Electrical cabinets have a door or removable panel for easy access to the contents within, while other styles of electronic enclosures snap together like a clamshell container. Though frequently boxy, stainless steel or aluminum enclosures can be rounded to accommodate disc shaped equipment like gauges and meters.
Common styles include portable, desktop, display, wall mounted and cabinet enclosures; the size and purpose of each style varies from small enclosures that can fit in a hand or pocket to boxes with clear panels for touch screens. Electrical enclosures are found in every industry and application that requires electricity unless the conduits, connections, switches and control panels are exposed to the open air, which is rare.
Electrical enclosures range from very simple to complex designs. Some are hollow aluminum boxes with a lid that mount to the wall while others are molded plastic forms that have knockouts, vents and internal structures to keep certain components in position.
Flanges and gaskets ensure a tight seal. A vast number of enclosures are made from aluminum that has been extruded, a process in which bars of the metal are pushed through dies.
Stainless steel is usually cold rolled and constructed into a box or cabinet with welded seams. Plastic electrical enclosures are lightweight, durable, and, in certain situations, tougher than steel. For heavy duty enclosures, however, metal is generally used. Because of the variety of material, styles and uses, certain standards have been put into place to uphold the quality of the enclosure and to communicate what the user can expect.
The National Electrical Manufacturers Association, or NEMA, certifies enclosures based on what conditions they can withstand; for example, Type 6P protects its contents from solid foreign objects, brief submersion, corrosion and the external formation of ice. Underwriters Laboratories is an organization with its own set of standards, and its abbreviated marking of UL can be found on over 20 billion electronics worldwide.
The International Protection Rating, also known as the IP Code, offers a third rating system.