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An electrical enclosure is a
cabinet
Cabinet or The Cabinet may refer to:
Furniture
* Cabinetry, a box-shaped piece of furniture with doors and/or drawers
* Display cabinet, a piece of furniture with one or more transparent glass sheets or transparent polycarbonate sheets
* Filing ...
for
electrical
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...
or
electronic equipment
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification a ...
to mount
switch
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of ...
es,
knobs and
displays
A display device is an output device for presentation of information in visual or Touch, tactile form (the latter used for example in Refreshable Braille display, tactile electronic displays for blind people). When the input information that is su ...
and to prevent
electrical shock
Electrical injury is a physiological reaction caused by electric current passing through the body. The injury depends on the density of the current, tissue resistance and duration of contact. Very small currents may be imperceptible or produce a ...
to equipment users and protect the contents from the environment. The enclosure is the only part of the equipment which is seen by users. It may be designed not only for its utilitarian requirements, but also to be pleasing to the eye. Regulations may dictate the features and performance of enclosures for
electrical equipment in hazardous areas, such as petrochemical plants or coal mines.
Electronic packaging
Electronic packaging is the design and production of enclosures for electronic devices ranging from individual semiconductor devices up to complete systems such as a mainframe computer. Packaging of an electronic system must consider protection ...
may place many demands on an enclosure for heat dissipation,
radio frequency interference
Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrost ...
and
electrostatic discharge
Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two electrically charged objects caused by contact, an short circuit, electrical short or dielectric breakdown. A buildup of static electricity can be caused ...
protection, as well as functional, esthetic and commercial constraints.
Standards
Internationally,
IEC
The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...
60529 classifies the
ingress protection rating (IP Codes) of enclosures.
In the United States, the
National Electrical Manufacturers Association
The National Electrical Manufacturers Association (NEMA) is the largest trade association of electrical equipment manufacturers in the United States. Founded in 1926, it advocates for the industry, and publishes standards for electrical product ...
(NEMA) publishes
NEMA enclosure type The National Electrical Manufacturers Association (NEMA) defines standards used in North America for various grades of electrical enclosures typically used in industrial applications. Each is rated to protect against personal access to hazardous pa ...
standards for the performance of various classes of electrical enclosures. The NEMA standards cover corrosion resistance, ability to protect from rain and submersion, etc.
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. Mass-produced equipment will generally have a customized enclosure, but standardized enclosures are made for custom-built or small production runs of equipment. For plastic enclosures ABS is used for indoor applications 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.
Metal cabinets may meet the conductivity requirements for electrical safety bonding and shielding of enclosed equipment from electromagnetic interference. Non-metallic enclosures may require additional installation steps to ensure metallic conduit systems are properly bonded.
Stainless steel and carbon steel
Carbon steel
Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states:
* no minimum content is specified or required for chromium, cobalt ...
and
stainless steel
Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...
are both used for enclosure construction due to their high durability and corrosion resistance. These materials are also moisture resistant and chemical resistant. They are the strongest of the construction options. Carbon steel can be hot or cold rolled. Hot rolled carbon steel is used for stamping and moderate forming applications. Cold rolled sheet is produced from low carbon steel and then cold reduced to a certain thickness and can meet ASTM A3666 and ASTM A611 requirements.
Stainless steel enclosures are suited for medical, pharma, and food industry applications since they are bacterial and fungal resistant due to their non-porous quality. Stainless steel enclosures may be specified to permit wash-down cleaning in, for example, food manufacturing areas.
Aluminum
Aluminum is chosen because of its light weight, relative strength, low cost, and corrosion resistance. It performs well in harsh environments and it is sturdy, capable of withstanding high impact with a high malleable strength.
Aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
also acts as a shield against electromagnetic interference.
Polycarbonate
Polycarbonate
Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily work ...
used for electrical enclosures is strong but light, non-conductive and non-magnetic. It is also resistant to corrosion and some acidic environments; however, it is sensitive to abrasive cleaners. Polycarbonate is the easiest material to modify.
Fiberglass
Fiberglass
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
enclosures resist chemicals in corrosive applications. The material can be used over all indoor and outdoor temperature ranges. Fiberglass can be installed in environments that are constantly wet.
Terminology
Enclosures for some purposes have partially punched openings (knockouts) which can be removed to accommodate
cables
Cable may refer to:
Mechanical
* Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof
* Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...
,
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 box
An electrical junction box (also known as a "jbox") is an enclosure housing electrical connections. Junction boxes protect the electrical connections from the weather, as well as protecting people from accidental electric shocks.
Construction
...
es, street cabinets or technically as
serving area interface
The serving area interface or service area interface (SAI) is an outdoor enclosure or metal box that allows access to telecommunications wiring.
Alternate names
*Access point (AP)
*Cabinet (cab)
*B-box (breakout box)
*Cross box
*Cross-connect b ...
.
Telecommunications
Telcordia Technologies
iconectiv is a supplier of network planning and network management services to telecommunications providers. Known as Bellcore after its establishment in the United States in 1983 as part of the break-up of the Bell System, the company's name ...
has proposed generic requirements for telecommunication equipment cabinets. These requirements were developed with the input of United States service providers, and are intended to provide a suitable environment for telecommunication companies’ electronic and passive equipment that is housed in above-ground cabinets or enclosures (typically pad- or pole-mounted) in an outside plant environment. The proposed standard includes functional design criteria, generic mechanical and environmental requirements, desired features, and performance tests.
Telecommunication huts are fully assembled or modular field-assembled transportable structures capable of housing an electronic communications system. These huts provide a controlled internal environment for the communications equipment and occasional craftspersons. The huts are designed with locks, security, and alarms to discourage access by unauthorized persons. Huts can be provided with a decorative facade to comply with local building requirements. Telecommunications huts are designed to withstand climate conditions existing throughout the USA including rain, snow, sleet, high winds, ice, sand storms, earthquakes and lightning.
Fire Risk
Electrical enclosures are prone to
fires
Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products.
At a certain point in the combustion reaction, called the ignition point, flames are pr ...
that can be very intense (in the order of the
megawatt
The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units, International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), ...
) and are hence an important topic of fire safety engineering.
See also
*
19 inch rack
A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is wide. The 19 inch dimension includes the edges or "ears" that protrude from each side of the equ ...
*
Cable management
Cable management refers to management of electrical or optical cable in a cabinet or an installation. The term is used for products, workmanship or planning.
Cables can easily become tangled, making them difficult to work with, sometimes res ...
*
DIN rail
A DIN rail is a metal rail of a standard type widely used for mounting circuit breakers and industrial control equipment inside equipment racks. These products are typically made from cold rolled carbon steel sheet with a zinc-plated or chroma ...
*
Housing (engineering)
In engineering, a housing or enclosure is a container, a protective exterior (e.g. shell) or an enclosing structural element (e.g. chassis or exoskeleton) designed to enable easier handling, provide attachment points for internal mechanisms (e.g. ...
*
Rack unit
A rack unit (abbreviated U or RU) is a unit of measure defined as . It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby th ...
*
Telco can
The serving area interface or service area interface (SAI) is an outdoor Enclosure (electrical), enclosure or metal box that allows access to telecommunications wiring.
Alternate names
*Access point (AP)
*Cabinet (cab)
*B-box (breakout box)
*Cr ...
*
Utility box art
Utility box art is a form of street art whereby Enclosure (electrical), utility boxes on city streets are painted or otherwise covered in artwork.
In cities around the world
*Auckland, New Zealand: Paul Walsh series of painted utility boxes. Wa ...
*
Utility vault
A utility vault is an underground room providing access to subterranean public utility equipment, such as valves for water or natural gas pipes, or switchgear for electrical or telecommunications equipment. A vault is often accessible directly fro ...
References
External links
NEMA website
IEC IP definitions, and a comparison of IEC<>NEMA definitionsElectrical Enclosure with Terminal