7 Things Panel Builders Should Consider Before Choosing an Electrical Enclosure
7 Things Panel Builders Should Consider Before Choosing an Electrical Enclosure
For a panel builder, selecting an electrical enclosure involves much more than finding a box with the right dimensions.
The enclosure has to protect the equipment, meet the specifications of the application, accommodate the components inside, and allow the finished panel to be built efficiently. Material, environmental ratings, modification requirements, weight, communications, availability, and total installed cost can all affect the decision.
There is also no single enclosure material that is best for every application. Painted steel, stainless steel, aluminum, fiberglass and polycarbonate each offer advantages depending on the operating environment and requirements of the project.
Here are seven factors panel builders should consider when selecting an enclosure.
1. Start With the Environment and Required Ratings
Before considering material or price, determine what the enclosure will be expected to withstand.
Will it be installed indoors or outdoors? Will it be exposed to rain, washdown, temporary submersion, UV radiation, corrosive chemicals, extreme temperatures or physical impact?
The required environmental rating should help narrow the choices.
For example, a NEMA 4 enclosure provides protection against rain and hose-directed water, while NEMA 4X adds corrosion-resistance requirements. Applications requiring protection against temporary submersion may call for NEMA 6 or 6P.
Panel builders should also verify the actual certifications required by the project rather than assuming that an enclosure's construction or material automatically provides a particular rating.
2. Choose the Material for the Application
Material selection is often a tradeoff between strength, corrosion resistance, weight, cost and ease of modification.
Painted steel is widely used for industrial control panels. It is strong, familiar to panel shops, readily available and well suited to many indoor industrial applications. Its primary limitation is corrosion when the coating is damaged or when it is used in aggressive environments.
Stainless steel provides excellent mechanical strength and corrosion resistance. It can be an excellent choice for food processing, washdown, chemical and other demanding applications. However, stainless enclosures can be heavy, relatively expensive and more difficult to machine.
Aluminum combines relatively low weight with good corrosion resistance and can be an attractive option for certain outdoor and industrial applications. Cost, alloy selection and environmental compatibility should be considered.
Fiberglass is nonconductive and highly corrosion resistant, making it a long-established choice for wastewater, chemical processing and outdoor applications. Depending on the application, panel builders may need to consider UV exposure, machining characteristics, fibers created during modification and long-term surface appearance.
Polycarbonate is lightweight, corrosion resistant, electrically nonconductive and well suited to many outdoor and industrial environments. It can also offer high impact resistance and is relatively easy to machine. Maximum enclosure size, operating temperature and the specific chemical environment should be evaluated before specifying it.
Rather than asking which material is universally “best,” the better question is: Which material provides the right combination of properties for this particular installation?
3. Consider Usable Space, Not Just Outside Dimensions
A 24 × 20 × 10-inch enclosure does not necessarily provide 24 × 20 × 10 inches of usable component space.
Panel builders need to account for the mounting plate, DIN rail, wire duct, terminal blocks, power supplies, PLCs, drives, disconnects and other components, along with adequate space for wiring and servicing them.
Door-mounted devices can further reduce available depth.
It is also worth considering future service requirements. A panel that technically fits but leaves little room for a technician to access terminals or replace components may create problems long after it leaves the panel shop.
The enclosure should provide enough space to build, wire and service the panel, not simply enough room to contain the components.
4. Look at the Cost of Modification
The purchase price of an empty enclosure is only one component of its true cost.
Most control panels require some combination of holes, cutouts, cable-entry points, ventilation openings, HMI openings, pushbutton holes, printing, labels or other modifications.
If those operations are performed by the panel shop, they require equipment and labor. They can also introduce opportunities for scrap or rework.
For a prototype or one-off panel, performing modifications internally may make perfect sense. Panel builders already equipped with automated machining equipment may also be able to modify enclosures very efficiently.
For repeated production, however, having an enclosure supplier provide CNC machining, printing, engraving or assembly can reduce panel-shop labor and improve consistency from enclosure to enclosure.
The useful comparison isn't simply:
Enclosure A costs $X and Enclosure B costs $Y.
It is:
What does the enclosure cost when it is ready for my technicians to begin installing components?
5. Think About Weight and Installation
Weight can become increasingly important as enclosure size increases.
Steel and stainless steel provide excellent structural strength, but larger enclosures can require additional people or lifting equipment during handling and installation.
Aluminum, fiberglass and polycarbonate can substantially reduce enclosure weight, which may make transportation, wall mounting, pole mounting and field installation easier.
Weight may be relatively unimportant for a small enclosure mounted to a machine. It can become a much bigger consideration when technicians are installing a large control panel outdoors, on a pole, at a remote site or in an awkward location.
Panel builders should therefore consider not only how the enclosure moves through their own shop, but also how the finished panel will be installed in the field.
6. Consider What Is Communicating From Inside the Enclosure
Control panels increasingly contain equipment that communicates wirelessly.
Cellular modems, Wi-Fi equipment, remote monitoring systems, IoT gateways and other wireless devices can change the enclosure-material decision.
Metal enclosures can attenuate radio-frequency signals, which may require an external antenna or other design accommodations. In many applications this is easily addressed and may have little influence on enclosure selection.
Nonmetallic materials such as fiberglass and polycarbonate, however, generally allow RF signals to pass through the enclosure more readily. This can simplify some wireless installations by allowing antennas or communications equipment to remain inside the enclosure.
For panels incorporating wireless communications, RF performance should therefore be considered before the enclosure material is selected, rather than after the panel has already been designed.
7. Evaluate the Supplier Along With the Enclosure
For a panel builder, the enclosure supplier can affect production almost as much as the enclosure itself.
Before standardizing on a product, consider questions such as:
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Are the required sizes readily available?
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Are mounting plates and accessories available?
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Can the supplier provide CAD files and dimensional drawings?
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Can enclosures be supplied machined or otherwise modified?
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Can modifications be repeated consistently across production runs?
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What are normal lead times?
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Is technical support available when an application doesn't fit the standard catalog?
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Are the required UL, cUL, NEMA or other certifications documented?
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Are domestic-content requirements relevant to the project?
A technically suitable enclosure isn't particularly useful if it becomes the component holding up completion of the panel.
The Best Enclosure Is the One That Fits the Entire Application
There is no enclosure material that wins every comparison.
Steel can provide an economical and robust solution for countless industrial control panels. Stainless steel is difficult to beat where mechanical strength and severe corrosion resistance are required. Aluminum provides an attractive combination of weight and durability. Fiberglass has decades of successful use in corrosive environments. Polycarbonate combines low weight, corrosion resistance, impact resistance and wireless transparency in a material that works particularly well for many modern control applications.
The panel builder's job is to balance those characteristics against the environmental rating, component layout, modification requirements, installation conditions, production volume and project budget.
Choosing the right enclosure at the beginning of the project can mean fewer modifications, less assembly labor and fewer surprises when the finished panel reaches the field.
And ultimately, that's what a panel builder should expect from an enclosure:
It should protect the controls without making the panel harder to build.
Have an Enclosure Application You're Working On?
Choosing between steel, stainless steel, fiberglass, aluminum and polycarbonate often comes down to the details of the application.
If you're evaluating an enclosure for a new control panel, Fibox can help you determine whether a polycarbonate enclosure is the right fit. Our team can review your size, environmental rating, mounting, modification and production requirements and help identify an enclosure solution that works for your build. Talk to Fibox About Your Application. Or, explore the Fibox Polycarbonate Enclosure Range to compare sizes, ratings and available options.