Anyone who works with electrical enclosures will commonly encounter two different systems for rating an enclosure’s protective qualities: NEMA ratings and IP ratings. When evaluating an enclosure, you’ll need to understand how these rating systems work and what they tell you about an enclosure.
NEMA and IP ratings have some things in common, but they also have several important differences. Knowing the differences between them can be hugely important when it comes to choosing the right electrical enclosure. Below, we’ll discuss the essentials you need to understand the NEMA vs. IP difference.
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The NEMA rating scale is a metric for evaluating an enclosure’s protective qualities using a combination of letters and numbers. NEMA ratings get their name from the National Electrical Manufacturers’ Organization, a trade group that maintains the standard.
At the low end of the scale, ratings like NEMA 1 and NEMA 2 provide a basic level of indoor protection. On the high end, ultra-tough outdoor enclosure ratings like NEMA 6P offer resistance even to prolonged submersion. In between are many common ratings like NEMA 12 and NEMA 4X, which are widely used in industrial and commercial applications.
Read more about NEMA enclosure ratings in our complete NEMA ratings guide.
IP (ingress protection) ratings are another metric widely used to evaluate protective electrical enclosures. These ratings are derived from a standard in the International Electrical Code known as IEC 60529.
Every IP rating has a two-digit number that rates the enclosure’s ingress protection performance. The first digit rates protection against solids such as dust and debris, while the second digit rates protection against the ingress of water. Models with waterproof and dustproof IP ratings, such as IP66 enclosure boxes or IP68 enclosure boxes, are the most commonly used.
Read more about IP ratings in our ultimate guide to IP ratings.
Many enclosures are rated on both the NEMA and IP scales. Most Polycase enclosures, for instance, are tested for compliance on both standards. However, there may be times when it’s appropriate to specify an enclosure rating on one scale or the other.
Local regulations and standards are one factor to consider. NEMA ratings are more common in North America. In the rest of the world, and particularly in the EU and Asia, IP ratings are the standard choice.
Think about the intended application of your enclosure as well. In the industrial and manufacturing sectors, NEMA ratings are more common. Other sectors, such as consumer electronics, tend to use the more universal IP rating system.
Some businesses also choose to specify a NEMA enclosure box when they need specific protective features that IP ratings don’t cover. A business that needs corrosion-resistant enclosures, for example, will often specify NEMA 4X enclosures. In these instances, it can also be useful to compare specific ratings head-to-head, such as in our NEMA 4 vs. IP65 comparison.
It’s usually possible to convert IP ratings into rough equivalents on the NEMA rating scale. Our IP to NEMA conversion guide provides a quick outline of how to do it. It’s as simple as finding the digits of your desired IP rating on the chart, and then finding the NEMA ratings that each digit lines up with.
However, the reverse conversion—NEMA ratings to IP ratings—isn’t always possible. Since NEMA ratings consider some factors that IP ratings don’t, there are no equivalent IP ratings for some NEMA ratings. NEMA 4X and NEMA 3S, for example, do not have equivalents on the IP scale.
In the U.S., NEMA and IP ratings are voluntary standards. That means that there’s no central authority proactively administering compliance and testing on the ratings that electrical enclosure manufacturers place on enclosures. Thus, it’s important to choose a reputable manufacturer that offers UL testing on its enclosures.
UL, formerly known as Underwriters Laboratories, is the most widely used testing authority for all kinds of industrial and commercial products. Manufacturers submit their products to UL for testing in a rigorous series of laboratory procedures designed to measure NEMA and IP compliance.
Polycase makes it easy to see the UL test results of any enclosure model. Simply find the model’s file number in its product description, and then enter it in UL’s Product iQ database to see proof of UL certification. In addition to NEMA and IP, many of our enclosures are rated on the UL flame rating scale for resistance to extreme heat.
We’re always glad to assist our customers with questions about NEMA vs. IP ratings or any other enclosure related issue. Call our experts at 1-800-248-1233, or contact us online