Industrial Enclosures, a.k.a. panels, cabinets, racks, electrical enclosures, or wall boxes, are used to mount electrical components while also protecting them and preventing electrical shock to users.
Let’s take a look at what to review when ordering an enclosure for your application:
When determining what type of enclosure to order, knowing the environmental demands is paramount to proper protection. Saginaw extensively evaluates each material’s environmental resistances and has created this guide below detailing their enclosure options.
Common NEMA Enclosure Types
- NEMA 1 – Indoor Use/General Purpose: Protects against dust, light, and indirect splashing but is not dust-tight; primarily prevents contact with live parts; used indoors and under normal atmospheric conditions.
- NEMA 2 – Indoor Use: Drip-tight: Protects against against ingress of solid foreign objects (falling dirt); and provides a degree of protection to the ingress of water (dripping and light splashing).
- NEMA 3R – Indoor/Outdoor Use: Protects the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); provides a degree of protection against the ingress of water (rain, sleet, snow).
- NEMA 4 – Indoor/Outdoor Use: Protects against against ingress of solid foreign objects (falling dirt and windblown dust); the ingress of water (rain, sleet, snow, splashing water, and hose directed water); and the external formation of ice on the enclosure.
- NEMA 4X – Indoor/Outdoor Use: Same as NEMA 4 but with added protection against corrosion.
- NEMA 12 – Indoor Use: Enclosures constructed (without knockouts) to provide a degree of protection to personnel against access to hazardous parts; of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings); and to degree, the ingress of water (dripping and light splashing).
- NEMA 13 – Indoor Use: Protects personnel against access to hazardous parts; protects the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings); to a degree the ingress of water (dripping and light splashing); and to a degree against the spraying, splashing, and seepage of oil and non-corrosive coolants.
Once we’ve decided the materials and protection ratings, it’s time to move onto installation.
According to Saginaw:
Fluctuating temperatures are a panel’s worst nightmare! Finding the balance between optimizing space and ensuring the electrical components are protected against environmental factors can pose a challenge for any electrician. It’s important to evaluate your enclosure’s environment and its exposure to ambient heat, internal heat, and solar gain. Excessive heat or cold can seriously compromise both the performance and functionality of enclosure as well as the equipment it houses.
What temperatures can an enclosure sustain?
Plastics, windows, gaskets, and coatings are tested for their performance – (Resistance Hot and Cold). Cooled to a temperature of -30°C (-22°F) for a period of 24 hours and then subjected to an impact and crush-resistant test. Heat – Max. temperature for outdoor application 60°C/140°F test in circulating air for 168 hours have a tensile strength of not less than 75% and an elongation of not less than 60% of values determined for unaged samples. At the conclusion of the tests, there is no visible deterioration, deformation, melting, or cracking of the material. See UL 50E and CSA 22.2 for complete requirements.
Internal Heat Load
Internal heat produced by electronic components can considerably increase the internal temperature (Heat Rise). Just 1 watt added to 1 cubic foot of space can increase the internal temperature by as much as 3°F. Different base materials have different thermal conductivity (K Value), stainless, aluminum, fiberglass, and steel, as well as their finish, greatly influence internal heat dissipation and heat rise, so they must be considered when determining the proper thermal management options for the application. Choosing the incorrect thermal management option can compromise the performance, components, electronics and environmental rating of your enclosure.
Solar Gain, High Ambient Conditions
Solar Gain refers to the increase in temperature in a space that results from solar radiation. The amount of solar gain increases with the strength of the sun. Shading, reflection, and color can be used to minimize the effects and cooling requirements. An enclosure in a location with full exposure to the sun and 0 watts of internal heat load can reach temperatures that exceed 160°F and exceed the performance limitation of test requirements and of some materials, such as polycarbonate windows.
As a result of the internal heat load, higher temperatures, solar gain or the combination of some or all of these conditions, cooling systems, such as Air Conditioners, Heat Exchangers or Chillers are often required in many applications whether the enclosure is indoors or outdoors, insulated or un-insulated.
Low Ambient Conditions
Heat may be required to raise the temperature of the control panel, for freeze protection, reduce humidity, prevent damage to the electronic components or improve efficiency of electronics. As the complexity of electronics increase it becomes even more critical to safeguard the enclosures.
Mounting heaters along with a thermostat near the bottom of the enclosure provides the best performance. Thermostats can be incorporated as part of the heater or as a standalone item. The controller should be positioned in a neutral location that will provide an average humidity or temperature reading. Placing the thermostat too close to the heater may provide a reading that is influenced by the direct heat of the heater.
Read More About Thermal Management Here!
- Saginaw’s Enviro-Therm NextGen AC Units are here!
- Protecting VFDs from Overheating
- 5 Things I Didn’t Know About Thermal Management
- Filterfan®, Heat Exchanger, Chiller or a Cooling Unit?
- Protecting Electrical Enclosures from Summer Heat with Pfannenberg
- Choosing the right temperature set point with Pfannenberg
A major selling point (to us, at least) is the fact that Saginaw not only designs their enclosures, but they thoroughly test their products to make sure they meet quality standards. When it comes to coping with weather conditions, they don’t cut corners; as pointed out when reviewing their ratings tests.
What does the Type 4 & 4X test involve?
Protection against the ingress of water – hose down test. The enclosure and its external mechanisms are subjected to a stream of water from a hose that has a 25 mm (1 in) inside diameter nozzle that delivers at least 240 L (65 gal) per minute. The nozzle is held 3.0 to 3.5 m (10 to 12 ft) from the enclosure, and the spray of water is directed at all points of potential water entry, such as seams, joints, external operating mechanisms, and the like. The nozzle is moved along each test point one at a time in a uniform nominal rate of 6 mm/sec (¼ in/sec). A conduit is installed to equalize internal and external pressures. At the end of the test no water has entered the enclosure. See UL 50E and CSA 22.2 for complete requirements.
IEC IP Code Second Character in IPX5 & IPX6 test?
Protection against the ingress of water – IPX5 & IPX6 hose down test. The enclosure and its external mechanisms are subjected to a stream of water from a hose that has a 6.3 mm (0.25 in) for IPX5 and 12.5 mm (0.5 in) for IPX6 inside diameter nozzle that delivers at least 12.5 L (3.5 gal ) per min. on IPX5 or at least 100 L (26.5 gal ) per min. on IPX6.
The nozzle is held 2.5 m to 3 m (8.2 to 9.8 ft) for IPX5 and IPX6 from the enclosure, and the spray of water is directed at all surface areas likely to be sprayed. Test duration is 1 minute per square Meter per surface with a minimum of 3 minutes total test duration for IPX5 and IPX6. The nozzle is moved along the entire test surface. A conduit or vent is installed to equalize internal and external pressures.
→ Click to learn more about IEC 60529 ratings at the IEC (International Electrotechnical Commision) website.
For all enclosures in outdoor applications with direct exposure to rain, snow, and ice, a drip shield is always recommended; and in most applications, it is required. Drip shields minimize risk related to long term exposure to rain and damaging effects of snow and ice being trapped in the external cavity of the door and enclosure body and prolonged exposure to water that may lead to water being absorbed into the gaskets.
An enclosure which is not adequately vented and is in an outdoor or wash down environment may lead to leakage due to drastic temperature changes caused by rainfall or hose down. An enclosure that is subjected to a temperature differential of just 20 to 30 degrees, for instance one with an internal temperature of about 85°F which has hose directed water applied with city water (average temperature of 55°F), can result in damage to the seal. When the water is applied, the temperature inside the enclosure rapidly drops, the air contracts and creates a vacuum inside the enclosure that starts to draw water through at the weakest link, or even pull water through the gasket, almost immediately and until the pressure is equalized. The smaller the enclosure or part the quicker this reaction occurs.
An enclosure in an outdoor application will be exposed to conditions that are far more severe considering the solar gain, the internal temperature rise of the enclosure and rain temperatures which can be as low as 32°F. In some installations, a wire conduit may be found adequate to serve as a vent to equalize the pressure, but in most applications, is not enough. In Type 4 and 4X Enclosures, no drain holes are required or provided, so it is increasingly important that sufficient ventilation exists or Type 4, 4X drains or breathers are added to equalize pressure.
Type 3R Rainproof
A true complete Type 3R Rainproof enclosure is provided with drip shield and drainage holes which also serve as ventilation to equalize pressure as required. A multi-listed enclosure such as an enclosure listed as Type 3R, 4 & 12 is provided with additional instructions for the installation of a drip shield and drainage holes. What does the Type 3R Rain test involve? Enclosures with a conduit connected shall be mounted as in actual service, the test apparatus consists of at least three spray heads mounted in a water supply pipe rack. The enclosure is positioned in the focal area of the spray heads so that the greatest quantity of water is likely to enter the enclosure. The water pressure is maintained at 34.5kPa (5 psi) at each spray head and a continuous water spray shall be applied for one hour. Type 3R enclosure is considered to have met the requirements if at the conclusion of the test a) There is no accumulation of water within the enclosure; and b) No water has entered the enclosure at a level higher than the lowest live part.
*Engineering Note: Saginaw Control & Engineering recommends when enclosures are installed in full outdoor exposure and extreme weather environments the use of drip shield, ventilation and drainage. Saginaw Control & Engineering does not recommend the use of polycarbonate viewing windows for use as type 4, 4X, IP55, IP56, IP66 or any outdoor application when installed in full exposure and extreme weather environments. Carefully considered and evaluate your end use environment for the all reasons described above.
Corrosion Protection Requirements
The corrosion protection requirements for a Type 1, 12, 3R, 4 and 4X are very specifically targeted and an enclosure may be manufactured out of a combination of materials that meet the corrosion requirements for the enclosure type, although may not be adequate for your application without making changes.
What does the Type 4X Corrosion test involve?
Indoor Type 1 & 12-24-hour salt spray. The test apparatus shall consist of a fog chamber, a salt-solution reservoir, a supply of compressed air, atomizing nozzles, support for the enclosure, provision for heating the chamber, and means of control. Type 3R, 4 test – 1200-hour moist carbon dioxide-sulfur dioxide-air, 600-hour salt spray. (Two not scribed specimens and two specimens scribed with edges taped) Outdoor Type 3RX, 4X is the same Type 3R, 4 test with an additional 200-hour salt spray or 800 hours…
The primary targets of the corrosion test requirements are with respect to water, salt water, and basic air pollutants. Salt water should be considered when applications are near coastlines and roadways, effects of salt air can be a concern from 5 miles to 25 mile inland depending on the region. The effects of salt water can be extreme even with type 304 stainless steel although the effects are more cosmetic than structural or functional. If cosmetics are critical, then type 316 stainless steel may be a better choice, yet it is not impervious to rust and staining caused by airborne debris and chemicals that may end up on the material surface.
Performance with respects to common outdoor exposure and water:
Ascending Scale from 1-8 – 8 being the highest performing.
1) Steel with Polyester Powder coat finish
2) Steel with Epoxy Zinc Rich Powder base with Polyester Powder coat finish
3) Galvannealed Steel with polyester Powder coat finish
4) Aluminum with polyester Powder coat finish
Galvanic corrosion (sometimes called dissimilar metal corrosion) is the process by which materials in contact with one another oxidize or corrode, accelerating the deterioration of one of the metals. In some instances, galvanic corrosion can even be helpful in some applications. For example, if pieces of zinc or copper are attached to the bottom of a steel water tank, the zinc or copper will become the anode, and it will corrode. The steel in the tank becomes the cathode, and it will not be affected by the corrosion. This technique is known as cathodic protection. The metal to be protected is forced to become a cathode, and it will corrode at a much slower rate than the other metal, which is used as a sacrificial anode.
*Engineering Note: Saginaw recommends the application and environment is carefully evaluated for the reasons described above. There may be chemicals, acids, solvents, or gasses outside the scope of the corrosion resistant requirements in your application or environment that will adversely affect the performance of the enclosure or materials used in its construction.
Common Applications Where Purge Can be Used:
- Pharmaceutical manufacturing
- Oil and gas production
- Chemical processes
- Petroleum industry
- Refineries and terminals
- Paint users and manufacturers
- Original equipment manufacturers
- Dusty Environments
- Powder, fiber, and related manufacturing processes
Usually pressurizing your NEMA enclosure is an option reserved for applications where your electrical equipment is too large to be made explosion-proof or too high-powered. While a simple process, pressurization can offer a significant advantage in safety and durability.
Before power can be switched on, the air inside the enclosure is replaced with air known to be free of flammable gas. Purge gas, normally compressed air, keeps the internal pressure of an enclosure above the pressure outside the enclosure thus keeping external flammable gas from entering.
Saginaw has categorized their hazardous information into three sub-groups: class, division and groups. When determining what type of protection to aqcuire, undestanding the exact type of hazards you’re dealing is incredibly useful.
When deciding where the enclosure will reside, we need to consider which of the following equipment zones it will be installed:
Equipment surfaces intended to be in direct contact with food.
Equipment surfaces may contact and then drain drip, or splash back into food or onto surfaces that are intended to be in direct contact during operation of equipment.
While it is common to find enclosures in the Non-Contact Zones, this is not always the case and determining washdown capabilities will come in handy while dealing with any food-grade production. Saginaw performs extensive testing to accurately determine the protection ratings of their enclosures.
Saginaw’s Type 4 & 4X test Hydro Test
Type 4 & 4X test Hydro Test Protection against the ingress of water – hose down test. The enclosure and its external mechanisms are subjected to a stream of water from a hose that has a 25 mm (1 in) inside diameter nozzle that delivers at least 240 L (65 gal) per minute. The nozzle is held from 3.0 to 3.5 m (10 to 12 ft) from the enclosure, and the spray of water is directed at all points of potential water entry, such as seams, joints, external operating mechanisms, and the like. The nozzle is moved along each test point one at a time in a uniform nominal rate of 6 mm/sec (¼ in/sec). A conduit is installed to equalize internal and external pressures. At the end of the test no water has entered the enclosure. See UL 50E and CSA 22.2 for complete requirements.
*There’s an important difference between IP69 and IP69K!
IEC 60529 IP69 testing is for equipment, like control panels or electrical equipment that is installed in areas that get washed (pharmaceutical manufacturing, industrial food packaging), and IP69K is not part of the IEC 60529 standard at all, rather it’s an added requirement used for equipment installed on road vehicles ISO 20653.
Saginaw recommends that when type 4 or 4X when installed were extreme temperature change may occur evaluate that adequate ventilation is present or add proper ventilation, breather or drainage vent in order to equalize internal pressure of the enclosure.
Carefully considered and evaluate your end use environment. There may be chemicals, cleaning/sanitizing chemicals, wash down pressures and temperatures that may be outside the scope of the requirements in your application or environment that will adversely affect the performance of the enclosure or materials used in its construction.
Here’s an example of the general design and construction criteria for an application with daily exposure to corrosive food products, cleaning and sanitizing chemicals:
- Concealed with removable pins min. of 3/16 inch Diameter– easily cleanable while in place and designed to be disassembled (with the use of tools) for routine cleaning
- Continuous hinges not being used in a food zone
- Flange trough gutter above the enclosure door opening
- Seams wider than ⅛ in (0.13 in, 3.2 mm) which are sealed by continuous weld or are flashed and sealed
- Welded joints and seams have been de-burred
- 300 Series Stainless Steel – Type 304 or Type 316 stainless steel (most commonly used)
- If coated steel, organic coating such as powder coat
- Coatings, including metallic coatings such as zinc (galvanized), zinc alloys, or chrome plating, not used to render exposed materials corrosion resistant except on hinges, latches, and similar replaceable hardware.
- Easy-to-clean fasteners including slot-head quarter-turn latches
- No exposed threads or projecting screws or studs in a food or splash zone
- Leg stands provide a minimum unobstructed clearance of 6 in. beneath the enclosure
- Is not mounted directly to a wall, 2 inch minimum clearance
Sub-Panel stud mounted to the back of the enclosure:
- 25 lbs per square foot
Sub-Panel channel mounted with standard mounting kit (ref. Free-Standing enclosure and SCE-FSPS mounting kit):
- 20 lbs per square foot
Sub-Panel channel mounted with Heavy Duty panel supports:
- 30 lbs per square foot
Surface Load (Top, Bottom, Back, Right, or Left Sides):
- Wall-Mount enclosures 25 lbs per square foot
- Free-Standing enclosure 35 lbs per square foot
Doors (Concealed and continuous hinge):
- 15 lbs per square foot
Saginaw Control & Engineering enclosures are designed to withstand concurrent forces in any horizontal direction equal to 0.5 times the maximum internal capacity + enclosure weight, and a static force in any vertical direction equal to 0.4 times the equipment weight. Equipment weight should not exceed load capacity to maintain structural integrity.
Enclosures made of 0.075”, 0.104”, and 0.125” carbon and stainless steel construction maintain tensile strength of 70/80 ksi and a yield strength of 60/75 ksi. ANSI specification C1010.
Finally, after protecting your enclosure from the elements, thermal irregularities, hazardous materials and potential seismic problems, its time to look at EMI (Electromagnetic Interference).
What is EMI?
Electromagnetic radiation, which adversely affects circuit performance, is generally called EMI (electromagnetic interference). Many types of electronic circuits are susceptible to EMI and must be shielded to ensure proper performance. Conversely, emissions radiating from sources inside electronic equipment may threaten circuits within the same or nearby equipment. To protect the performance integrity of electronic equipment, electromagnetic emission from commercial equipment must not exceed levels set by the FCC, VDE and other organizations. Further standards set EMI levels to which electronic equipment must itself be immune.
What is EMI Shielding?
Shielding is the use of conductive materials to reduce radiated EMI by reflection and/or absorption. Shielding can be applied to different areas of the electronic package from equipment enclosures to individual circuit boards or devices. Effective placement of shielding causes an abrupt discontinuity in the path of electromagnetic waves. At low frequencies, most of the wave energy is reflected from a shield’s surface, while a smaller portion is absorbed. At higher frequencies, absorption generally predominates. Shielding performance is a function of the properties and configuration of the shielding material (conductivity, permeability and thickness), the frequency, and distance from the source to the shield.
What does Grounding have to do with EMI Shielding?
Grounding issues affect both safety and EMI emissions. Conductive components are grounded to protect equipment users from electric shock. If a system is properly grounded, and all conductive elements which a user might touch are theoretically at zero, protection shielding against EMI emissions is commonly provided by a conductive enclosure. The separate parts of the enclosure must be electrically bonded together and grounded for the shielding to work. Disruption in the conductive continuity between parts adversely affect shielding performance. Proper grounding of PCBs and shielding enclosure components is also a method for reducing board-generated EMI. However, improper or ineffective grounding may actually increase EMI emission levels, with the ground itself becoming a major radiation source.
A word about EMI Regulations
Government regulations in the US and many other countries prohibit electronic products for emitting EMI that could interfere with radio and television receivers. European regulations also include EMI immunity levels, which are expected to find their way into future US (FCC) standards.
Where is Emi Shielding needed?
EMI shielding is used for computers, medical devices, telecommunication, and many other types of electronic
equipment. As new emission and immunity requirements are placed on these devices, the importance of shielding grows. Among the typical applications for EMI shielding are the following:
Metal housings for electronic systems provide inherent levels of EMI shielding, dependent on factors such a metal type and flange surface thickness. Plastic and other non-conductive material used for lightweight housings can be metallized with sprayable conductive paints, thin film metal coatings, or plating. Laminates of metal foil and plastic film can be formed and die cut into Faraday cages and shadow shields.
Doors, cable ports, vents, windows, access panels and other openings in an otherwise shielded electronic package are pathways for radiated EMI. A variety of gaskets and specialized conductive materials are available for adding shielding around door seams and the perimeters of other openings. Shielding vents and windows are designed to reduce the amount of EMI passing through them. The amount of EMI leakage through an opening is a function of the maximum dimension of the opening. A long, narrow slit, like the gap around the edge of a door, will leak much more radiation than a round hole of the same area. The imperfect joints between panels or covers and enclosure walls are typical “slots” where EMI can efficiently escape or enter a shielded enclosure. Conductive EMI gaskets inserted between panel mating surfaces will provide low resistance across the seam and thereby preserve current continuity of the enclosure.
Enclosures are continuously welded for maximum shielding protection, all door openings are masked off prior to painting, in preparation for shielding gaskets to be applied for indirect bonding of enclosure and enclosure doors.
Shielded gasket and tape is applied to the enclosure door and door opening depending on the enclosure design.
- Enclosures are designed to provide maximum shielding for RF energy.
- Shielded Type 12 enclosures can provide attenuation greater than 100dB from 14.5 khz. To 430 mhz. For electric fields, 40 to 100d8 at 1 ghz.
- A standard non-shielded enclosure can attenuate about 20dB at 1 ghz.
All door hardware is installed with earth nuts for direct bonding, and a ground stud on all doors and body for additional indirect bonding.
Any other cutouts or openings in the enclosure may require additional shielding.
What started off as a simple box to put electrical components in has evolved into a highly tuned piece of equipment with detailed criteria for any application. Saginaw is at the forefront of this technology with their advanced designs and extensive testing.
Visual thinker in a digital spectrum, or in layman’s terms….I make all the visual content for Marshall Wolf Automation 🙂 With a background in video advertisement and film production, I work with MWA’s marketing department to keep our customers reading our blogs and viewing our products.