When it comes to rating and evaluating electrical enclosures, there are two big names every engineer and designer should be familiar with: IEC and NEMA. These are two organizations that have developed ingress protection rating systems for electrical enclosures. 

You’ve probably seen these rating systems when looking at different models of electrical enclosures. Most of Polycase’s enclosures include both IEC ratings, which are more commonly called IP ratings, and NEMA ratings. But it’s important to know the different uses of each rating system. 

What are the differences between IEC vs. NEMA, and how should you use these systems when evaluating an electronics enclosure? We’ll discuss the two systems and their differences below. 

Electrician installing electric cable wires and fuse switch box. Multimeter in hands of electricians detail.

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IEC and IP Ratings

The International Electrotechnical Commission (IEC) is the regulatory organization that develops and maintains the standards for IP ratings. The IEC’s standards cover a wide variety of different electrical and electronic technologies, but the relevant standard here is IEC 60529, which defines how the IP system is used to rate an enclosure’s ingress protection.  

IP ratings are one of the two types of systems typically used to rate enclosures. The format of these ratings uses the letters “IP” followed by a two-digit number, such as IP56 or IP68. The first number rates the enclosure’s protection against ingress from solids, such as dust or dirt, as well as from accidental contact with the device. The second number rates the enclosure’s protection against ingress from liquid water. 

For a full guide to using IP ratings and how to interpret them, see our complete guide to IP ratings. 

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IP Rating Example: IP65 Enclosure

IP65 enclosures are waterproof enclosures that have the following protective qualities: 

  • Completely dust tight protection against particulate ingress
  • Protection against water droplets, splashing and low-pressure water jets from any angle, with limited ingress but no damage permitted

An example of an IP65 enclosure from Polycase is the Polycase WC Series of outdoor polycarbonate enclosures. These outdoor enclosures are precision molded from durable polycarbonate that stands up to tough conditions, and their transparent polycarbonate covers make it easy to see key information without removing the cover. 

WC-23 Outdoor Enclosure with Clear Cover

Polycase WC-23 Polycarbonate IP65 Enclosure

NEMA and NEMA Ratings

The National Electrical Manufacturers Association (NEMA) is a U.S. trade association for businesses that manufacture electrical components. The organization also issues ingress protection standards for electrical enclosures. NEMA ratings are the other common type of enclosure ratings system and are used mostly in the United States (as opposed to the more international IP rating system). 

The format of these ratings is the letters “NEMA” accompanied by a number and sometimes more letters, such as NEMA 12 and NEMA 4X. The number corresponds to a ranking on the scale, although a higher number doesn’t always mean better protection. The letter indicates additional specific protective properties. 

For more information on the NEMA ratings system, see Polycase’s complete guide to NEMA ratings. 

NEMA Rating Example: NEMA 4X Enclosure

NEMA 4X enclosures are waterproof enclosures that have the following protective qualities: 

  • Protection against ingress from splashing water, precipitation, hose-directed water or ice on the enclosure
  • Protection from dust, dirt and various airborne particulates
  • Resistance to corrosion 

An example of a NEMA 4X enclosure from Polycase is the Polycase AN Series. The AN Series are our premier aluminum enclosures and are designed to offer weatherproof outdoor protection that also looks professional and polished in any environment. 

Polycase AN-01P Diecast Aluminum NEMA 4X Enclosure

Polycase AN-01P Diecast Aluminum NEMA 4X Enclosure

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IEC vs. NEMA: The Final Word

In the IEC vs. NEMA question, there’s no one right answer—just two rating systems that function slightly differently. However, note the following:

  • NEMA ratings are used mainly in the U.S., while IP ratings are internationally recognized. 
  • NEMA ratings include factors, such as corrosion resistance, that IP ratings don’t consider. 
  • It’s usually possible to roughly convert IP ratings to NEMA ratings. However, the reverse is often not possible, since NEMA ratings include a greater range of factors than IP ratings do.  
  • The IP rating scale is generally simpler and easier to use at a glance than the NEMA scale, since it goes in ascending order and includes fewer complicating factors. 
  • Both IP and NEMA ratings should be certified by enclosure testing through a standards organization, such as UL. 

Polycase is glad to help our customers find an enclosure that checks every box with style, including an IP rated enclosure or NEMA rated enclosure. Just call us at 1-800-248-1233 or contact us online for more information. 

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