An electrical enclosure is a box or housing that accommodates electrical equipment or components. These enclosures protect electrical equipment from outside elements such as dust and moisture, and prevent direct contact with users and physical damage. The criteria that need to be considered during the electrical enclosure selection process are environment, application, and standards.
Understanding Electrical Enclosure
An electrical enclosure is like the casing of a desktop computer. Since there are many different types of electrical equipment, so are the various forms of electrical enclosures. They could be small, handheld, wall-mounted, or large floor-standing enclosures. The manufacturers produce electrical enclosures by using a range of raw materials such as metal, plastic, and fiberglass.
Electrical enclosures are used in industrial, commercial, and household settings. Industries that use these enclosures are telecommunication, oil, gas transportation, and power generation. Their application is also found in homes, office buildings, and retail stores. The places where these enclosures are used in industrial settings are factory floors, process control rooms, and machine shops. Electrical enclosures are quite useful in corrosive environments such as chemical plants and food processing facilities.
Environmental Considerations
Environmental considerations have immense importance for enclosures that are exposed to the elements. Two enclosures specialists, Kreeley and Coulton, found that all enclosures are affected by the cooling effect or the formation of condensations if environmental conditions change to a certain extent. The cooling effect of a standard enclosure happens when moisture reaches the protected areas of the enclosure. This moisture may condense on the internal components of the electrical and electronics equipment.
Condensation creates major problems for the electrical and electronics industries. The short-term problem resulting from condensation is electrical tracking and leakage. The medium and long-term problems include degradation of insulation and corrosion of components.
The corrosive environment is another important environmental consideration because many applications that enclosures protect are susceptible to chemical attacks. Both stainless steel and carefully selected plastic could be good construction materials for enclosures. Besides these two materials, most other materials have good resistance to certain chemicals. However, they can’t resist all types of chemical attacks.
The construction method of enclosures is also important because electronic components held inside enclosures need to be protected from harmful gases. In a marine or coastal region, for example, salt-laden air may cause damage to electronic components surrounded by enclosures.
IP and NEMA Ratings Explained
IP and NEMA ratings refer to enclosure classifications. While IP rating refers to the European standard and is internationally recognised, NEMA is applicable in North America. Both ratings classify enclosures based on their level of protection against environmental hazards. IP ratings consider only two parameters, which are protection against the ingress of water and particles, whereas the NEMA ratings are more elaborate as they include all IP ratings parameters as well as additional parameters such as corrosion, ice, and hazardous conditions.
The IP rating is denoted with two numbers(which could be three in some cases). The first number is for protection against solid objects, and the second is meant for liquid. For example, an enclosure with IP rating 69 indicates that it will provide complete protection from dust and high pressure, high temperature sprays.
NEMA rating, on the other hand, is simple. It is expressed with a single number. An enclosure with NEMA rating standard 4, for example, indicates that it is ideal for outdoor use. It will provide protection against rain, sleet, windblown dust, and damage from external ice formation.
Both IP and NEMA ratings cover protection levels against water, dust, and impacts on enclosures. They are applicable for industrial enclosure ratings. IP rating for water ingress is a scale that covers all types of water ingress that may affect enclosures. This scale starts with one that indicates enclosures least protection ability against ingress of water and ends with nine the maximum ingress protection.
NEMA rating indicates protection from all types of water by alpha numerical values 3S and 4X. NEMA rating 4X, for example, indicates protection against rain, splashing water, and hose-directed water.
Since the first part of the IP rating indicates the level of protection against solid objects, if the IP marking starts with 5 or 6, it indicates the enclosure is almost or fully dust protected. When it is about dust protection in the context of NEMA rating, number 13 indicates protection against dust.
IP rating’s third number refers to protection against mechanical impact. However, often time it is omitted since it is not part of IEC 60529. If the third number is 6, for example, it indicates protection against the impact of a 5 kg weight falling from 40 cm height. NEMA rating, on the other hand, does not specify protection against mechanical stress or impact.
Material Selection and Durability
Selecting the right materials for your electrical enclosures is important because a wrong choice would make your valuable electrical equipment vulnerable to irreparable damage. Electrical enclosures manufacturers use various materials to manufacture their products. What type of material you would choose for your enclosure depends on factors such as impact, corrosion, heat, and other conditions. Electrical manufacturers primarily use metal, plastic, and fiberglass to produce electrical enclosures.
It is important to compare these materials in terms of strength, corrosion resistance, weight, and cost when selecting your enclosure material.. Steel enclosures are strong and durable that offer excellent protection against impact, vibration, and corrosion. These enclosures are suitable for a harsh industrial environment where enclosures are subject to high wear and tear. Steel enclosures are expensive, which counterbalances their performance.
The plastic enclosures are lightweight and inexpensive and are used in a range of applications. They do not offer good durability, and are less popular. They are ideal for environments where enclosures are not subject to extreme conditions. Similar to metal enclosures, the fiberglass enclosures are strong, durable, and provide good resistance to impact, chemicals, and heat. They are more expensive than plastic enclosures but withstand high levels of wear and tear.
Application Specific Needs
Application-specific needs refer to a particular environment or situation where an equipment needs to function. All electrical enclosures used in various industries are custom-made because key environmental factors, such as temperature, humidity, and potential exposure to dust, water, and chemicals, and the size and type of the equipment they house, varies from industry to industry. Electrical enclosures built for hazardous environments, for example, need to meet standards so that they can protect electrical equipment placed inside of them from fire and explosions.
Hazardous environments refer to locations that are filled with flammable gases, vapours, combustible dusts, easily ignitable fibers, and flying particles.
Telecommunication enclosures are another special need enclosure. These are fully enclosed, tailor-made Weatherproof electrical boxes to organise and protect sensitive electrical equipment used in telecommunication, such as servers, routers, and switches.
Key factors that come into play in electrical enclosure selection are the environment( temperature, humidity, presence of chemicals), required enclosure ratings- NEMA and IP standards- materials(metals, plastic, or fiberglass), and whether it would be used in a specific industry. For industrial applications that often involve complex installations, consultations with experts are recommended.
