If not shielded, electromagnetic interference (EMI) can also disrupt the performance of the circuitry inside the enclosures.
Electronic enclosures are frequently made of aluminum, although other metals like stainless steel as well as plastics are also used. They are usually rectangular and box-like, ranging in size from a few square inches to being as large as a room.
Many boxes are between four and eight inches in length but there are hundreds of available dimensions. Some aluminum enclosures are rounded to accommodate hockey puck-shaped equipment, such as meters or gauges.
Because of the range in sizes, aluminum enclosure boxes are used in almost any industry that requires electrical equipment. Computers are available in aluminum unibody enclosures or can be fitted inside an enclosure for protection.
Handheld devices are frequently encased in aluminum; small remotes like car starters and garage door openers are just a few examples. Power switches, electrical conduits and other critical controls are protected by aluminum enclosures in order to prevent contact between the contents of the box and personnel or substances.
Depending on the application, aluminum enclosures may have a solid lid or a hinged door that can be locked for security. Internal gaskets or a continuous flange protects against dust and moisture while bezels and corner screw covers hide the hardware used to mount the enclosure, though not all enclosures are mounted.
Recesses in the surface of the enclosure allow for labels, foil keyboards or further modifications. Aluminum is rugged with a high degree of structural strength, so they are often self-supporting. Many enclosures are made from extruded aluminum, which is aluminum that was pushed through a die to create the desired cross-section.
Enclosures may also be cast or made from sheets of rolled aluminum and given a powder coat or enamel finish. Aluminum enclosures can be made to custom specifications depending on the intended use.
NEMA, the National Electrical Manufacturers Association, publishes protection ratings and certifications similar to the International Protection Rating (the IP Code). However, they do not map onto each other because they include different characteristics.
The most common NEMA enclosure types are 1, 3R, 4X and 12 and range from indoor, non-hazardous use to outdoor protection from rain, sleet, snow and ice.