Electrical cabinets are rectangular boxes that range from about half a foot to over 5 feet tall in varying depths and widths.
Electrical cabinets are typically made out of aluminum or stainless steel, though plastics such as polycarbonate polystyrene or acrylonitrile butadiene styrene (ABS) are options as well. Tall cabinets may require a door or body stiffener for strength.
Electrical cabinets are usually found in the lower levels or utility rooms of buildings and residences but can be found on street corners or partially hidden by landscaping in a park, for example. They are also widely used in practically every industry, protecting circuit breakers, operations switches and connections that would otherwise be exposed. Outdoor cabinets can be certified to withstand dirt, wind, rain, sleet, snow and ice formation on the enclosure’s exterior in addition to surviving earthquakes and tornadoes.
Cabinets used indoors must be tough as well and are usually dust and watertight. When used in a meat or dairy plant, for example, the lines are routinely washed down on a daily basis, and any water that enters the enclosure would grow bacteria and begin to rust the cabinet and electrical components. In chemical or finishing plants the cabinets may encounter corrosive or hazardous materials that other enclosures could not withstand.
The cabinets are generally made from cold rolled steel with continuously welded seams. After receiving a finish such as a powder coating, the knockouts, doors and handles are added. Accessories such as shelves or drawers are optional but can be useful, depending on the application.
Warning labels and locking mechanisms deter vandalism and tampering. Some cabinets stand on the floor while smaller models have mounting holes in the back for fasteners to directly mount the enclosure to the wall; other cabinets have external mounting feet for a complete seal and maximum protection from contaminants.
Electrical cabinets are certified and rated by NEMA, the National Electrical Manufacturers Association, the IP Code (International Protection Rating) and by UL, the Underwriters Laboratories.
Requirements and standards help keep workers and technicians safe besides effectively communicating the specifications of electrical cabinets to interested buyers. For example, a cabinet with a NEMA Type 1 certification is rated for indoor use in a non-hazardous situation with the main purpose of preventing accidental contact. A rating of IP 66 means that the enclosure is totally protected from dust and against temporary flooding of water.
Another threat that electrical cabinets protect their contents from is electromagnetic interference (EMI, also known as radio frequency interference, or RFI) which is a disturbance that affects electrical circuitry due to electromagnetic radiation or conduction from an external source. Special coatings are available to shield an enclosure’s contents from EMI/RFI.