NEMA 12 Enclosures: Frequently Asked Questions

Keeping your electrical devices safe at work is a critical task that you shouldn’t trust just any enclosure to perform. The NEMA rating system is one of many that our customers around the world trust to make sure they’re getting the enclosures that meet the protection needs of their applications, and the NEMA 12 enclosure rating is one that Polycase’s enclosure experts often get questions about.

To make sure our customers have the best and most accurate information about NEMA 12 enclosures at their disposal, we’ll spend this article covering some of our most commonly asked questions about these enclosures. If you’re interested in learning more about the NEMA rating system and how you can decide if a NEMA 12 enclosure is right for you, read on for some helpful answers and tips!

1. What is the NEMA rating system?

The NEMA rating system is a popular classification system developed by the National Electrical Manufacturers Association. It’s a numerical rating scale used to standardize the levels of protection expected from various types of electrical enclosures. The scale includes 16 different ratings and sub-ratings, with each rating indicating a different level of protection from environmental hazards. These hazards include:

• Accidental contact with workers’ hands or body parts
• Ingress of flying dust, falling dirt and other atmospheric particles
• Weather conditions such as snow and rain
• Contact with splashing or dripping water
• Contact with hose-directed water
• Corrosion hazards such as salt water
• Submersion at a limited depth
• Formation of ice on the enclosure’s exterior
• Fire and explosions caused by combustible vapors and dust

Taking these factors into account is critical for selecting the right electrical device enclosure. Before you start your selection process, identify which of these hazards are relevant to your application and use that information to guide your choice.

2. What is a NEMA 12 enclosure?

The NEMA 12 rating is a common NEMA rating used for devices that need moderate indoor protection against dust and liquid ingress. It’s a good choice for when you need basic protection at an affordable price.

A NEMA 12 rated enclosure should protect the device inside against:

• Accidental personnel contact
• Solid foreign particles circulating in air, such as lint, flyings, dirt and dust
• Settling of dirt and dust
• Dripping and light splashing of non-corrosive liquids
• Seepage of oil and coolants from external sources

It’s important to remember that the NEMA scale isn’t in a strict ascending order, so always check the chart to decide what NEMA rating is right for your application. Some other “lower” NEMA ratings, such as NEMA 4 and NEMA 6, provide more robust protection that’s suitable for outdoor applications.

3. Can a NEMA 12 enclosure be used outside?

NEMA 12 enclosures are not recommended for outdoor use. They’re rated for indoor use only. Although Polycase manufactures all of our enclosures to a high standard of quality, it’s risky to count on NEMA 12 enclosures to provide the performance you need in environments for which they aren’t designed.

A NEMA 12 enclosure may offer adequate performance for an outdoor application in areas with mild weather and low precipitation. But it doesn’t provide the level of protection that most device designers and users will want for their outdoor devices. We’ll discuss some other enclosure types later in this article that are better suited for outdoor use, such as NEMA 4.

4. Is NEMA 12 weatherproof?

It’s common for device designers to need protection against common outdoor weather hazards such as rain, snow, splashing mud and more. However, NEMA 12 enclosures usually aren’t the best NEMA type for these circumstances.

A NEMA 12 enclosure is not completely weatherproof, nor is it intended to be. Although it provides some protection against water and foreign object ingress, you’re better off choosing an enclosure rated for weatherproof performance, such as a NEMA 4 or NEMA 6 rated enclosure.

5. Is NEMA 12 explosion-proof?

A NEMA 12 enclosure is not explosion-proof. Enclosures resistant to explosion hazards are designed according to much more rigorous standards of durability that NEMA 12 enclosures typically don’t need.

If you need explosion-proof performance from your enclosure, you’ll want to go with a NEMA 7 or NEMA 8 rating. These enclosure types are designed to offer protection in indoor environments with explosion hazards from flammable gasses or vapors. Chemical processing plants and petroleum refineries are common places where you’ll often find these enclosures.

6. Is NEMA 12 watertight?

NEMA 12 enclosures offer good protection against light water ingress such as dripping and splashing. However, they are not designed to be completely watertight, and do not offer sufficient protection against hose-directed water, intense splashing or submersion.

If you need a watertight enclosure, look into NEMA 4 and NEMA 6 rated enclosures. These enclosure types are designed with watertight gaskets and offer much tougher and more thorough protection against water ingress. NEMA 6 enclosures are even designed to survive limited submersion.

7. What’s the difference between NEMA 4 and NEMA 12?

A NEMA 4 or NEMA 4X enclosure is designed to offer the performance you need for outdoor applications. The NEMA 4 series enclosures offer weatherproof protection against common precipitation hazards such as:

• External ice formation
• Rain, sleet and snow
• Splashed water

A NEMA 4X enclosure also offers additional protection against corrosive environments, such as salt water, that can cause enclosures to corrode and break down.

Again, while NEMA 12 enclosures provide some protection against water hazards, they are not recommended for outdoor use and may not provide sufficient protection. They also do not offer corrosion protection.

8. What’s the difference between NEMA 3, NEMA 3R, NEMA 3RX, NEMA 3S, NEMA 3SX and NEMA 12?

The biggest general difference between the NEMA 3 rating series and NEMA 12 is that NEMA 3 enclosures are rated for outdoor use, while NEMA 12 enclosures are not. Whereas a NEMA 12 enclosure offers only the previously listed protections, NEMA 3 series enclosures also are rated to protect against basic weather hazards such as rain, snow and sleet. If you need outdoor-level performance, NEMA 3 is usually the minimum level of NEMA-rated protection to consider.

The NEMA 3S and NEMA 3SX models also have an additional feature: Enclosures with this rating must be operable when covered in ice. If this is a feature your application demands, note that these are the only NEMA ratings that specify these performance standards.

If you need corrosion protection, it’s also worth looking into the NEMA 3RX and 3SX ratings, which provide all of the same specs as a NEMA 3R rating, but with extra resistance to corrosion.

9. What’s the difference between NEMA 6 and NEMA 12?

NEMA 6 enclosures offer some of the highest-grade waterproofing and weatherproofing protection available. Like a NEMA 4, a NEMA 6 enclosure is rated to protect against weather conditions and hose-directed and splashed water. But it has the added benefit of protecting against water ingress from temporary submersion. Its even tougher counterpart, the NEMA 6P rating, is designed to protect against even prolonged submersion.

NEMA 12 enclosures, again, do not offer most of these features. If your application requires protection against submersion, you should definitely go with a NEMA 6 enclosure.

10. What’s the difference between NEMA 12 and NEMA 12K?

The difference between NEMA 12 and NEMA 12K enclosures is the presence of knockout options in the body of the enclosure. Knockout panels are pre-cut panels that are designed to be easily removed with a tool. They allow a person installing or assembling a device to remove only the areas of the enclosure that are necessary. NEMA 12K enclosures are a good choice for indoor electrical junction boxes, as many electricians find knockout panels to be useful for the flexibility it gives them when wiring these devices.

11. What’s the difference between NEMA 12 and NEMA 13?

A NEMA 13 rating is similar to a NEMA 12 rating, but it includes additional protection against splashing and spraying of oil and coolants. It’s another solid general-use indoor enclosure option that can offer better performance for environments with numerous mechanical devices, where oil and coolants will likely be more plentiful.

12. What IP rating is equivalent to a NEMA 12 rating?

The IP rating scale is an international rating scale for electrical enclosures (NEMA is used mainly in the United States). It uses a series of two-digit numbers to rate the protective qualities of enclosures. The first number represents the enclosure’s protection against solid foreign objects, while the second represents its protection against liquids. A NEMA 12 enclosure is roughly equivalent to an IP54 enclosure, but with a few key caveats.

The NEMA standards are actually slightly more strict than the IP standards — so, if an enclosure passes a given NEMA standard, it will meet the requirements for its equivalent IP rating, but the reverse is not guaranteed. Thus, a NEMA 12 enclosure will always meet the standards of an IP54 enclosure, but not all IP54 enclosures are necessarily NEMA 12 compliant.

You can find numerous NEMA to IP conversion guides online. However, you should treat all conversions as an approximation until you’ve fully consulted with your engineering staff on the issue.

13. What’s the difference between IP54 and NEMA 12?

As stated above, any NEMA 12-rated enclosure will be compliant with IP54 standards. However, IP standards do not include tests for resistance to corrosion, oil and/or coolant leakage and other common industrial hazards. If these are concerns, make sure you use NEMA ratings to make your enclosure selection.

14. What’s the difference between IP65 and NEMA 12?

IP65 rated enclosures offer a higher degree of protection against both water and dust. They are designed to be completely dust tight, as well as being protected against light-to-moderate water jets. They’re also suitable for outdoor use, which, again, means that they protect at a higher level than a NEMA 12 enclosure.

15. What kinds of materials are NEMA 12 enclosures available in?

You’ll be happy to know that NEMA 12 enclosures come in a wide variety of materials. Each has its own features and performance specs, and each is great for various different types of applications.

• Polycarbonate: A heavy-duty plastic polymer that offers light, tough performance and a high level of UV resistance.
• ABS Plastic: Another plastic polymer that offers great durability and is more affordable than some other options since it is meant to be indoors and not outdoors.
• Aluminum: This widely-used metal is as tough as it is attractive. Offers natural RFI and EMI shielding.

• Stainless Steel: When you want the ultimate in corrosion-resistant protection, stainless steel is the top choice — and it looks great, too.
• Carbon Steel: A common type of steel for construction and engineering, carbon steel can also offer NEMA 12 protection. Powder coating can increase its resistance to corrosive agents.

Any of these materials can make a great NEMA 12 rated enclosure, but heavier materials like stainless steel will often be rated for even higher levels of protection.

16. What are common applications for a NEMA 12 enclosure?

NEMA 12 enclosures are popular among electronics manufacturers all over the world for their dependable everyday performance. Some of their most common uses include:

• Electronic control panels for light manufacturing applications
• Indoor junction boxes
• Utility control devices

• Indoor wireless devices and other desktop devices
• Automation control panels
• Other indoor electronics applications requiring basic dust and water protection

Thanks to their variety of uses, NEMA 12 enclosures are among some of Polycase’s best sellers. Our wide selection of NEMA rated enclosures features options with NEMA 12 ratings and much more.

17. What kind of NEMA 12 rated options does Polycase have available?

Polycase has NEMA 12 rated enclosures in several styles and materials. In addition to NEMA 12, many models are also rated for higher standards such as NEMA 4/4X and NEMA 6/6P. Here’s a sample of our most popular models that meet NEMA 12 or better:

• Polycase AN Series: Heavy-duty and attractive die cast aluminum enclosures with natural RFI/EMI interference protection.
• Polycase WA Series: A popular and cost-effective enclosure series made from flame-retardant ABS plastic.
• Polycase WP Series: One of Polycase’s many polycarbonate offerings, crafted with UV stabilization technology to prevent warping and discoloration.

18. Can I get customized NEMA 12 enclosures from Polycase?

Yes! Polycase is proud to offer custom cutouts on many models, performed with our state-of-the-art CNC machining equipment, as well as custom digital printing. We love to create the best value for our customers by creating a one-stop shop for your electronic enclosure needs.

Our CNC machining can easily create the custom cutouts you need with a tolerance of just +/- 0.005 inches for ultra-precise quality. And our custom digital printing offers a full range of brilliant colors, printed directly onto your enclosures so you don’t have to worry about cracked or peeling labels.

Please note that at this time, we do not fabricate fully custom-manufactured enclosures and we do not offer CNC machining on our stainless steel enclosure models.

Polycase AN-11P model.

Hopefully, you now have a good idea of whether or not a NEMA 12 enclosure will meet the needs of your device. But if not, don’t worry — our electrical enclosure experts can help answer any questions you still have! Call Polycase for more information at 1-800-248-1233 or contact us online with your questions.