Electronic enclosures house a wide range of electronic equipment to protect them from damage, contaminants and interference. They are a standard component in most industrial and manufacturing settings because of the sensitive and important nature of electrical systems and wiring. Electronic enclosures are generally made of sheet metal, like stainless steel or aluminum, although fiberglass, high strength polymer plastics and other composites are also used.
Electronic enclosures range in size from one square inch that fits a simple pushbutton assemblage to an entire room that contains large computer networks and wiring. Electronic enclosures are frequently rectangular and box-like; other styles are round or have sloping sides. Lids, removable panels, access points and vents are necessary in some applications, and recessed tops accommodate labels and keypads. Enclosures for handheld devices can have soft ergonomic grips and a battery door. Many enclosures simply snap together, although a tight seal to keep out dust and water is available using lap joint or tongue and groove construction. Not only do electronic enclosures protect their contents from pollutants or moisture, they also shield the internal equipment from electromagnetic interference, or EMI, that would disrupt the efficient performance of the circuitry inside the enclosure. Sometimes referred to as electrical cabinets, electronic enclosures are widely used in the medical, automotive and agricultural industries to protect equipment and instruments but can be found in any electronic application. Electrical enclosures can be custom made for a precise fit although there are already thousands of enclosure designs. Factors to consider when selecting an appropriate enclosure include size, construction materials, mounting, security and NEMA type, which refers to the grading assigned by the National Electrical Manufacturers Association.
Metals have traditionally been the electronic enclosure material of choice until the recent developments in plastics and composite materials. Aluminum enclosures are good thermal and electrical conductors. Though tough, aluminum is also malleable and very lightweight, especially when rolled into sheets. Stainless steel enclosures are also durable and corrosion resistant, having properties similar to aluminum. Many computer enclosures are made of aluminum or steel. Although electromagnetic interference can travel through these metals, they can be coated with a substance to screen their contents from the rays. For smaller and more complicated enclosures, moldable polycarbonate plastics are used. One similar material is acrylonitrile butadiene styrene, a common thermoplastic called ABS. Its superior electrical insulation properties and impact resistance make it a popular choice for electrical enclosures. Because it is lightweight and shock absorbent, ABS is used for pocket and handheld enclosures that will be handled frequently. Other types of enclosures include protective, desktop and mounted styles. Enclosures can be mounted by screws or fasteners that fit through the designated holes in the back or bottom of the housing.
Electrical enclosures are boxes that protect electronic equipment such as conduits, connections and switches from the environment and from tampering. They are found in public places such as street corners or parks as well as in buildings and residences. These rectangular enclosures are typically made from plastic or metal, particularly steel and aluminum, in order to resist corrosion and shelter their contents from weather and vandalism. Electrical cabinets can be horizontally or vertically oriented and usually bear a warning to alert those nearby to the sensitive and potentially dangerous equipment inside. They may also be locked. Some cabinets are mounted. Standardized rack mount enclosures accommodate multiple equipment modules that are 19 inches wide. Protruding edges allow the module to be fastened to the frame, which is usually steel or aluminum because of their strength and load-bearing properties. Professional audio equipment, computer servers and other electronics are stored inside the rack mount enclosure, and many models have a door that can be shut and locked. Depending on the application, the enclosure may use thicker metal for the frame and be encased in reinforced plastic, carbon fiber or Kevlar. Instrument enclosures can also be rugged; some are designed specifically for use in demanding situations where explosions, earthquakes or tornadoes may occur. These enclosures are often made from die cast iron or aluminum and range from small rectangular metal boxes to circular enclosures that can protect head-mount style instruments.
NEMA enclosures are certified by the National Electronic Manufacturers Association depending on the type of application for which they are used. They range from Type 1 to 13 and identify whether the enclosure is intended for indoor or outdoor use, in non-hazardous or dangerous situations and what it can protect from. Type 1, for example, is for general indoor use to prevent accidental contact with the enclosed equipment. Type 4X can be used indoors or outdoors and protects against corrosion, windblown dust and rain, sleet, snow, splashing or hose-directed water and the formation of ice on the enclosure. NEMA Type 12 is for industrial use indoors to protect from lint, dust, dirt, fibers, dripping, seepage and dripping non-corrosive liquids. The enclosure may not have any knockouts (partially punched holes) or openings except for oil and dust-tight mechanisms or gaskets. Hinged doors must require a tool to open and have an external means for mounting. By certifying enclosures, NEMA helps manufacturers and distributors get exactly what they need and ensures that the electronics inside will be able to function properly and safely.
Electrical Enclosures - Attabox LLC
Electrical Enclosures - Attabox LLC
Electronic Enclosures - Equipto Electronics Corporation
Electronic Enclosures - Equipto Electronics Corporation
Electronic Enclosures - Attabox LLC
Electronic Enclosures - Attabox LLC
Given the types of electronic enclosures available on the market, buying one that has all the features you require can be a daunting task. To make the task easier, the best practice is to list out the features that are required; and based on your requirements; decide between a plastic enclosure, polycarbonate enclosure or metal box.
The features that you need to look for in electrical enclosures are: impact shock shielding, static shielding, magnetic shielding, dirt and dust proofing, and heat shielding. Here we will discuss why all these features matter and what their purposes include.
Pieces of modern electronic equipment, unlike their bulky predecessors, are to some degree fragile and can lose efficiency after being exposed to physical impact. Therefore, any electrical enclosure that you install needs to have impact shock shielding, which protects or minimizes the implication of physical impact and vibration to the equipment housed in the enclosure.
Some electric components can be damaged by static current; therefore, static shielding from external sources is an important attribute an enclosure must offer. Moreover, unexpected or abrupt electrical surges are damaging, especially to dormant parts. The chosen enclosure must provide appropriate grounding to withstand surges and keep components safe from the charge interferences.
When electricity passes through electrical components, heat dissipates invariably. Most electronic equipment, however, is heat sensitive, thus need shielding to work efficiently. Therefore, an enclosure should provide heat shielding. Some enclosures have in-built heat sinks, which do not allow temperature built up inside the enclosure and push the heat outside. However, heat sinks are normally used and are installed only when there is a special requirement.
Some electronic enclosures are dirt resistant, while some provide absolute proofing, even from windblown dirt. Similarly, some models offer water-resistant properties, whereas some are resistant even to ice. Almost all electrical components need protection from dirt and water, so it's best to determine your unique requirements before assessing their effectiveness in this area.
Similarly, like static current, electro-magnetic pulses are damaging to electronic components. Therefore, an enclosure should provide adequate protection against pulses. Although electro-magnetic bursts are very uncommon, expensive components especially should be housed in an enclosure that provides enough magnetic shielding.
There many considerations to ponder when selecting an electronic enclosure. Some enclosures are manufactured primarily for storing and transporting electronic equipment. Similarly, there are enclosures especially for computer equipment, like processors and hardware. The third type of enclosures is made for car electronics, which house and hold car electronics. The main purpose of these types of enclosures is to provide resistance to impact, heat and dirt, which are inherent to vehicles. Moreover, custom enclosures are also available, which are designed and fabricated based on a manufacturer's unique business requirements.
With ongoing advancement of fabrication technologies, electronic enclosures are increasingly manufactured from a wide variety of materials from fiberglass to polycarbonate and metal. Each building material provides its own advantages. However, with the large numbers of options available, it has also become difficult to decide the right material for an enclosure. Therefore, the following paragraphs offer advice on selecting the most appropriate material for electrical enclosures.
Heat release occurs as electric current flows from electrical components. There is nothing you can do to stop this release completely. Therefore, it is important that an enclosure insulates heat dissipated by the electrical equipment it houses. Thermal insulating capability probably is the most important factor while deciding the material for enclosures that holds sensitive components. Plastics boxes, such as polycarbonate enclosures, are considered the favored material when heat interference needs to be reduced, especially when the exterior temperature is low and components need protection from this low temperature. However, when electrical components generate too much energy and require heat transfer, then metal boxes made from stainless steel are better suited. Some electrical cabinets are configured with ventilation fans to offer constant operating temperatures.
If an enclosure is installed at a mine, electrical enclosures should be made from a material that is explosion proof. Similarly, if an enclosure is located outdoors, fiberglass is considered a preferred material; however, extended exposure to high or low temperatures can warp the fibers in the material. Therefore, other available polycarbonate alternatives should be used. For indoor use, where exposure to moisture can be reduced, aluminum enclosures are considered better materials.
Durability is by far the most important consideration, as no one wants to invest in new enclosures repeatedly over time. The durability of an enclosure, however, is determined by the installation location, as plastic enclosures can be deemed durable when not exposed to extreme environmental conditions. The common rule is, if you need enclosure for outdoors, always select sheet metal fabrication options, when durability is the only factor.
Enclosures sometimes can look incongruous with their environments, rendering related aesthetic efforts useless. Therefore, always consider the aesthetics of an enclosure material, especially when it is installed in an open space and interferes with design efforts.
For many manufacturers, price is the ultimate determinant un an enclosure decision. However, if price is the only determining factor, the selected enclosure can only provide additional headaches. Enclosures made from materials like fiberglass, plastics or lower-grade stainless steel, can save money upfront. However, over time, their performance may become a concern. Therefore, always make cost a contributing factor, but not the sole factor.
Other than the considerations described above, you also need to consider control of liquid water movement, control of heat flow, strength and rigidity, control of water vapor flow, and control of air flow. All these mentioned factors can help you to make a decision that best addresses your manufacturing needs. You may wish to seek the advice of your engineers or suppliers before making the final decision on an electronic enclosure.
Electronic Enclosure Types
A reduction in signal strength. Attenuation can occur naturally during
normal signal transmission, or it may be produced intentionally by inserting
a device in the path of the signal to reduce signal strength.
- The outer surface of the electrical enclosure.
- Often used interchangeably with either enclosure or rack. It is a piece of equipment designed to house or enclose something, such as electrical or process equipment.
- Seals that prevent water, dust, etc. from entering the enclosure at the point at which the cable is brought through the enclosure wall. Often, cable glands are installed via a gland plate.
- The unintentional or undesired exiting of potentially interfering electromagnetic energy from electrical/electronic sources.
- The ability of a material to resist burning, sparking, sputtering or dripping when brought into contact with a naked flame. Not all enclosures are flame retardant.
- Also called a "mounting plate" or "mounting pan," it is a shelf that allows the mounting of equipment inside the enclosure. Gear trays are typically located at the rear of the enclosure, though some may be movable.
- Removable section of the enclosure, usually located on the bottom. The gland plate can be removed to allow the easy fitting of cable glands.
- The extent to which a material can be magnetized.
- Term used to describe various styles of mounting bases for floor-mounted enclosures.
- Cables that have shields, such as braids or foils, to prevent EMI from entering or exiting the cable.
- The input current of the equipment as declared by the manufacturer.
- Vents that are used for HVAC or simple ventilation of shielded products, such as cabinets, rooms or enclosures. Some shielding vents also provide high shielding or air filtering.
- Shielding consisting of a thin conductive film on the glass or a fine-wire mesh or metalized open-mesh textile.
- A material that maintains shielding effectiveness across a seam or gap in an electronic enclosure.
- A NEMA rating indicating that the enclosures are intended for indoor, non-hazardous locations. Type 1 enclosures are mainly used to provide protection against limited amounts of falling dirt.
- A NEMA rating indicating that the enclosures are intended for use in outdoor, non-hazardous locations. Type 3R enclosures are mainly used to provide protection against falling rain and external ice formation.
- A NEMA rating indicating that the enclosures are intended for indoor or outdoor use in non-hazardous locations. Type 4 enclosures are mainly used to provide protection against splashing or hose-directed water, damage from external ice formation and windblown dust or rain.
- A NEMA rating indicating that the enclosures are intended for indoor use in non-hazardous locations. Type 12 enclosures are mainly used to provide protection against dripping, non-corrosive liquids, circulating dust and falling dirt.