service crew inspecting electrical installation

When it’s time to decide which level of defense you need your enclosure to provide, the standards can be confusing. You might have seen enclosure ratings like “NEMA 4” and “NEMA 12” mentioned often—but how can you tell which one is right for your needs?

Polycase offers NEMA-rated electrical enclosures in a wide variety of ratings and suited for many different applications. Our customers frequently have to make important decisions about what type of enclosure they need to use, and we’ve assembled this quick guide to help. So, without further ado: What is a NEMA enclosure rating, and are the common NEMA 4 and NEMA 12 ratings right for your environment? Let’s take a quick look and find out.

Reviewing the NEMA Enclosure Rating System

When electronics manufacturers need to know what kind of protection an electrical enclosure offers, the NEMA enclosure rating system is usually their first stop. It’s a list of standards established by the National Electrical Manufacturers Association that outlines how an enclosure performs against common environmental hazards such as water, dust and corrosion. Each level of the system identifies a degree of protection the enclosure provides against certain hazards, and different levels are recommended for different environments.

Here, we’ll look at two of the most common NEMA ratings our customers request: NEMA 4/NEMA 4X and NEMA 12. What level of protection do these ratings offer, and what options does Polycase have at this level?

NEMA 12: All-Around Indoor-Grade Protection

The NEMA 12 rating is a commonly used one, and is specialized for indoor applications. You’ll find these enclosures in use in factories, offices and service establishments around America. A NEMA 12 enclosure provides solid protection against a variety of common hazards, including:

  • Contact with hazardous parts
  • Settling, falling and airborne particulate matter such as dust and dirt
  • Light dripping and splashing of water
  • Leaking and dripping of oil and coolants

These enclosures are perfect for everyday protection in indoor work environments and available in a wide variety of materials from heavy-duty polycarbonate to stainless steel.

It’s important to remember that NEMA 12 is designed specifically for indoor applications. If you need outdoor-grade weatherproof protection, you’ll want to look for another common NEMA rating category: The NEMA 4 and NEMA 4X ratings.

retro style electric circuits and junction boxes

If you’re installing your device in an outdoor area, you’ll most likely need the weatherproofing of a NEMA 4 or higher rating.

NEMA 4 and NEMA 4X: Rugged Outdoor Resilience

Both NEMA 4 and NEMA 4X are also widely-used rating categories. Enclosures with these ratings offer an exceedingly tough construction and are suitable for outdoor installation.

The NEMA system isn’t in a strict ascending order of protection. Thus, the NEMA 4 and NEMA 4X rated enclosures actually offer a somewhat more advanced level of protection than NEMA 12 enclosures. NEMA 4 enclosures offer protection against the following hazards, both indoor and outdoor:

  • Splashing, dripping and hose-directed water
  • Access to hazardous parts
  • Foreign object ingress, including dirt, dust, fibers and flyings
  • Rain, snow and sleet
  • External ice formation on the enclosure

The NEMA 4X rating provides the same protections, but with additional protection against corrosion from hazards such as salt spray. NEMA 4X ratings are common among enclosures used in marine industries.

NEMA Rated Enclosures from Polycase

Our extensive enclosure selection includes both NEMA 12 enclosures, NEMA 4 enclosures, and NEMA 4X enclosures. Many are rated for three or more NEMA categories. Since NEMA ratings are voluntary and self-certified standards, Polycase employs Underwriters Laboratories (UL) approved testing to ensure that its enclosures perform to their specifications. Some also feature UL flame ratings or IK impact ratings.

Some of our most popular models include:

Polycase offers these enclosures in a wide range of sizes, as well as with customization and digital printing. Every one of our offerings is designed to offer outstanding value, reliability and ease of use to our customers.

open nema enclosure

Still have questions about what level of NEMA enclosures you need? Not sure if we have what you’re looking for? We can help! Get in touch with our electronics enclosure experts at 1-800-248-1233 or contact us online. When you’re ready to order, our quick quote option will get you on your way in no time.

In NEMA Plastic Enclosures, NEMA Rated Enclosures
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