Industrial Enclosures Selection Guide

Industrial electrical enclosures protect highly sensitive electrical and electronic devices from some of the toughest conditions–from flying dust to high-pressure hose-downs. Whether it’s a junction box, a control box, a data processing unit or another type of device, enclosure choice will often be a determining factor in a device’s performance and safety.

Hundreds of different factors affect the decision process when choosing an industrial device enclosure. Considering them all at once is overwhelming and can lead to mistakes—thus, it’s important to break out the most critical factors and consider them one at a time. Whether it’s enclosure size, enclosure material or the need for custom enclosure cutouts and labeling, each factor needs to be considered both independently and in terms of how it interacts with other factors.

Polycase offers hundreds of enclosure choices for industrial devices, in a wide variety of sizes and materials. In this guide, we’ll examine the key factors to be aware of when selecting an enclosure, and we’ll also provide our readers with some recommendations from among Polycase’s most popular enclosure models.

Choosing a Size

Industrial enclosures come in many sizes. When choosing the appropriate size for your enclosure, follow these key best practices:

• Keep a panel layout or device schematic on hand when choosing the size for the enclosure, as well as a bill of materials. Consider the size of each component and examine where each needs to be positioned.
• Make sure to leave sufficient room for running wires within the enclosure itself. Remember that some types of wiring need extra space to prevent the wires from creating interference with each other.
• If possible, consider the space in which the enclosure will be mounted. Make sure that the enclosure you select will fit in its mounting space, and if the enclosure has a swinging door, consider how much space it will need to open and shut.
• Identify which components in your device generate heat, as well as how much heat each one generates. Calculate how much space will be needed for ventilation structures to dissipate the device’s heat.
• It’s usually a good idea to choose an enclosure that has a little bit of extra space built in to accommodate assembly. The personnel or automated systems that are responsible for assembling the devices will be better able to move and manipulate the device’s elements when sufficient space is available.

Space is often at a premium for device designers, but it’s important to find the balance between space conservation, safety and device operability. Next, let’s look at how you can choose a material for your enclosure.

Choosing a Material

Your selection of material will affect many things about how your enclosure performs. The right material will help shield your device from the elements and protect its sensitive components, so it’s essential to choose a material with the properties that you need.

Think about the following questions when considering enclosure materials:

• Will your enclosure need customized cutouts for external features such as conduit or antennas? Cutouts are much easier to make in polycarbonate enclosures and ABS enclosures.
• Will your device be used indoors or outdoors, and what kinds of environmental hazards will your device enclosure be exposed to? Polycarbonate enclosures and stainless steel enclosures are renowned for their outdoor-grade toughness. Both are also great choices for enclosures that need protection from corrosion.
• Will your device enclosure need protection from RF interference? Aluminum enclosures offer natural RF shielding to protect your device.
• Will aesthetic appearance be a major concern for your enclosure? Aluminum enclosures and stainless steel enclosures are commonly selected for their elegant appearance.

Polycase offers all of the following enclosure materials:

• Polycarbonate Enclosures: A strong and sturdy plastic, polycarbonate is among the most popular industrial enclosure materials today. Polycarbonate is highly resistant to water and weather, making models like the Polycase ZH Series and Polycase WQ Series excellent choices for outdoor enclosures that need tough performance.
• Stainless Steel Enclosures: One of the toughest and most attractive enclosure materials, stainless steel is an excellent choice for devices where aesthetic elegance needs to be paired with tough performance. It’s also highly resistant to corrosion, making enclosures like the Polycase SA Series an ideal choice for maritime applications or other environments where corrosion is a concern.
• Carbon Steel Enclosures: A cousin to stainless steel, carbon steel packs much of the same durability at a lower price point. The Polycase SB Series are tough carbon steel enclosures with an anti-corrosion coating that gives them a NEMA 4X rating.
• ABS Plastic Enclosures: ABS plastic is a popular and cost-effective plastic material that’s often used for enclosures because it offers excellent durability for its price point. ABS enclosures, such as the Polycase AG series, are great for indoor and desktop enclosures.
• Aluminum Enclosures: Aluminum is an attractive and durable material that also features natural RF shielding. For this reason, aluminum enclosures, such as the Polycase AN Series, are perfect for devices that need to be shielded from radio wave interference (although they may not be a good choice for devices that need to transmit and receive Wi-Fi signals).

Ventilation and Cooling

Many industrial device components generate considerable heat. To manage and mitigate this heat, your enclosure may need to be ventilated. Moisture buildup is also a concern for many enclosures, necessitating the use of devices such as electrical enclosure vents that help prevent moisture from accumulating.

Devices that generate less heat may not require active ventilation in their enclosures. In these cases, passive ventilation systems such as enclosure ventilation cutouts may be sufficient. Note that metallic enclosures also radiate heat in ways that plastic enclosures don’t, creating potential hazards for devices that generate high heat.

Components that generate large amounts of heat often require devices such as blower fans to help dissipate heat from the enclosure. If your enclosure needs forced air ventilation, remember to order it with the appropriate customized enclosure cutouts. For more on the essentials of enclosure ventilation, see our article on venting options for instrument enclosures.

Rating Systems

The two most important rating systems for electrical enclosures are NEMA ratings and IP ratings. Both NEMA and IP ratings rate a device’s protection from environmental hazards such as dust, dirt, water spray and even submersion.

• NEMA ratings are used primarily in North America. They use a number and letter system to rate an enclosure’s ability to protect its contents from both liquids (such as water, coolant or oil) and solids (such as dirt, dust and debris). NEMA ratings also rate an enclosure’s resistance to other environmental hazards, such as corrosion from chemicals or salt water.
• IP ratings are used worldwide, particularly in Europe. Like NEMA ratings, they rate an enclosure’s protection against liquid and solid ingress using an ascending scale. Rather than a number and letter system, IP ratings use two numbers to rate an enclosure’s protective capabilities. The first number represents dust protection on a scale of one to six, and the second number represents liquid protection on a scale of one to eight. Unlike NEMA ratings, they do not rate enclosures on additional factors such as resistance to corrosion.

Frequently used NEMA ratings include:

• NEMA 12 Enclosures: Indoor enclosures that offer good basic protection against light dust, dripping liquids and condensation.
• NEMA 4X Enclosures: Outdoor enclosures that offer good protection against severe weather and dust, as well as against corrosion.
• NEMA 6P Enclosures: Outdoor enclosures that offer the highest available grade of protection, including protection against prolonged submersion.

Frequently used IP ratings include:

• IP55 Enclosures: Partially dust-tight enclosures with protection against low-pressure water jets and splashing.
• IP66 Enclosures: Dust-tight enclosures with protection against high-pressure water jets.
• IP68 Enclosures: Dust-tight enclosures with protection against continuous prolonged submersion.

For more information on these rating systems, see our in-depth guides to NEMA ratings and IP ratings.

Because NEMA and IP ratings are not provided or certified by any central authority, it’s important to look for enclosures that have had their ratings independently tested by Underwriters Laboratories. UL uses rigorous scientific processes that ensure every enclosure performs up to its rating, and their ratings are trusted worldwide by manufacturers, designers and engineers. Polycase enclosures are fully tested and certified by UL to ensure that they provide the performance that our customers expect.

Underwriters Laboratories also uses a flame resistance rating system to rate an enclosure’s protection against fire. The UL 94 flame rating standard, which rates the flame resistance of plastic materials, is particularly useful for choosing an enclosure.

Mounting Structures

You’ll also need to consider which mounting structures your enclosure will need to mount the components within. In most enclosures, components are mounted using one of the following mounting hardware types:

• Panel Mounting: Hardware is fastened to a back panel in the enclosure that is mounted directly onto the wall. Panel mounting is the preferred choice for harsh environments where vibration and shock are major concerns, but it may not be ideal for applications where hardware needs to be frequently changed. If you choose panel mounting, be sure to choose the right enclosure mounting panel that corresponds to your Polycase enclosure model.
• DIN Rail Mounting: Hardware is mounted on adjustable metal rails inside the enclosure. DIN rail mounting is slightly less secure than panel mounting, but it’s more flexible because of the standardized design of DIN rails, and it makes wiring and switch placement easy. Select the appropriate DIN rail hardware from Polycase when placing your order.
• Pole Mounting: Hardware is mounted onto a utility pole. Polycase offers pole-mounting hardware designed specifically for each of our most popular outdoor enclosures models.
• Rack Mounting: Hardware is mounted inside a rack space of standardized size. Some mounting racks feature slide-out design that allows easy access to the equipment inside.
• Desktop Mounting: Hardware is mounted directly onto a desktop. Desktop mounting provides easy access for frequently used hardware and is easy to change out. However, it provides minimal protection against environmental hazards.

Cutouts and Digital Printing

Many enclosures need to have areas cut out to accommodate cables, antennas and other critical elements. Polycase performs these modifications via CNC machining, which creates clean cutouts with very low margins of error. What’s more, our highly efficient machining process drastically reduces waste and scrap costs.

Device labeling can also be important for industrial enclosures, as many industrial devices require sophisticated labeling and diagrams for safe operation. Polycase’s digital printing offers a full spectrum of brilliant digital colors. We print directly onto the enclosure rather than a label, making our printing more resistant to cracks and weathering.

Polycase is proud to be a one-stop shop for enclosure cutouts and digital printing. Our online customization process allows customers to order custom machining and printing on right from our website, making it easy to get enclosures customized to your standards without using a separate contractor.

Popular Industrial Enclosures from Polycase

Polycase’s selection of industrial enclosures makes us an industry leader for cost-effective device protection. Each of these industrial enclosure series has something different to offer, and each could be the perfect solution for your industrial enclosure needs:

• Polycase ZH Series: Ultra-tough NEMA 6P-rated polycarbonate enclosures with a hinged cover for easy access.
• Polycase HD Series: Weatherproof NEMA 4X-rated polycarbonate enclosures with a silicone rubber gasket that helps prevent liquid ingress.
• Polycase SA Series: Classic stainless steel enclosures with NEMA 4X ratings, EFI/RMI protection and a secure keyed latch door. Internal mounting panel is included.
• Polycase WQ Series: NEMA 4X-rated hinged polycarbonate enclosures with a reinforced fiberglass base. Available with DIN rail, pole mounting and internal panel mounting kits.
• Polycase AN Series: Sturdy and attractive NEMA 6P-rated aluminum enclosures with natural EFI/RMI protection.

Polycase AN-11F Diecast Aluminum NEMA Enclosure

Other factors unique to each device and industry will also affect your selection. Need help from an enclosure expert with choosing the right enclosure for your device? Polycase will be happy to help. Just call us at 1-800-248-1233 or contact us online through our live chat or email.