Electronic and electrical products have become an elemental part of everyday life. It is hard to imagine any circumstance in modern living that is not touched by them. And while solid-state construction, printed circuit boards and microchip technology have made electronic components more durable than ever before, it is important to remember that electronics are susceptible to damage and failure by any number of factors.
Equally important, it is imperative that end users are provided a safe product. Electricity at any amperage can be physically harmful to humans, animals and equipment. Properly shielding components from the introduction of foreign objects, human touch or animal infiltration offers protection for everyone.
To address both of these needs, device designers and builders use electrical enclosures to shield sensitive devices and protect users. In this article, we’ll discuss NEMA enclosure types and other factors that will help determine what kind of electrical enclosure your application demands.
Some of the basic types of electrical enclosures that you’ll find on the market today include:
Some of these enclosure types can overlap with others, such as outdoor enclosures that are also waterproof and dust proof. However, in order to get an accurate assessment of an enclosure’s protective qualities, it’s important to be familiar with NEMA enclosure ratings and the other rating systems that provide a standard for an enclosure’s level of protection.
The electrical engineering and manufacturing industries have a number of options when it comes to standards for electrical enclosures. There are several industry associations and organizations that help educate and protect consumers by setting standards for the manufacture and use of electrical components.
When it comes to commercial and industrial applications, there are two organizations that immediately come to mind: the International Electrotechnical Commission (IEC) and the National Electrical Manufacturers Association (NEMA). These two organizations are associated, respectively, with the Ingress Protection (IP) rating scale and the NEMA rating scale.
The IEC serves the world’s manufacturers, and NEMA serves the United States. It’s also important to know about Underwriters Laboratories (UL) ratings. A UL rating is basically an IP or NEMA rating that has been tested by the independent safety experts at UL and verified to be in compliance with the relevant standards.
When considering your electronic enclosure options, it is important to understand the differences between IEC coding and NEMA coding. Specifically, IEC 60529 standard coding is based on three factors:
Finally, the degree of protection against water intrusion is assessed. It is very important to note that the standard does not say “liquid” intrusion, but it is specifically written to define only water intrusion. Of course, water is the most common liquid an enclosure would encounter in most settings, but the language of the IP Codes is meant specifically to cover the three most obvious factors that an enclosure is designed to protect. The IP Codes only consider the protection of the internal components.
Where the IEC 60529 Standards only inform of the enclosure’s capabilities against the entry of three factors, the NEMA 250 Standard provides a more robust set of variables detailed below.
The 20 different types of NEMA enclosure ratings detail standards ranging from the most basic level of protection against solid objects, to full submersion, to containing internal explosions.
The NEMA 250 Standard considers factors like whether the enclosure has knockouts or exposed parts that must remain operational in certain conditions. In an effort to best utilize the NEMA 250 Standard, you should consider several factors impacting the use of your enclosure. NEMA has grouped the codes to inform about certain corresponding conditions:
It’s important to know the differences in NEMA ratings so that you can select the correct enclosure for your needs. In some comparisons between common ratings, such as NEMA 12 vs. NEMA 4, the differences are substantial and will have major effects on whether your enclosure adequately protects its enclosed device. The codes [from NEMA 205-2003] for non-hazardous applications, the specific enclosure types, their applications and the environmental conditions they are designed to protect against, when completely and properly installed, are as follows:
NEMA 1 Rating: NEMA 1 enclosures are the most basic type of NEMA rated protection.
NEMA 2 Rating: NEMA 2 enclosures are a step up from NEMA 1 enclosures that include limited water ingress protection.
NEMA 3 Rating: NEMA 3 enclosures are the most basic type of outdoor enclosures and provide solid protection for non-hazardous outdoor environments.
NEMA 3R Rating: NEMA 3R enclosures are similar to Type 3, but provide slightly less protection against windblown dust. (See our article on NEMA 3 vs. NEMA 3R.)
NEMA 3S Rating: NEMA 3S enclosures are similar to Type 3, but must retain control operability when external ice forms on the enclosure.
NEMA 3X Rating: NEMA 3X enclosures are similar to Type 3 but provide additional protection against corrosion.
NEMA 3RX Rating: NEMA 3RX enclosures are a combination of the features of Type 3R and Type 3X.
NEMA 3SX Rating: NEMA 3SX enclosures are a combination of the features of Type 3S and Type 3X.
NEMA 4 Rating: NEMA 4 enclosures are strong outdoor enclosures suitable for a wide variety of outdoor and indoor applications.
NEMA 4X Rating: NEMA 4X enclosures are similar to Type 4, but include additional protection against corrosion.
NEMA 5 Rating: NEMA 5 enclosures are designed for indoor use to protect against a wide variety of airborne particulates and light water ingress.
NEMA 6 Rating: NEMA 6 enclosures are designed for tough outdoor applications that require high performance waterproof enclosures.
NEMA 6P Rating: NEMA 6P enclosures are similar to Type 6, but include additional protection against prolonged submersion.
NEMA 12 Rating: NEMA 12 enclosures are indoor enclosures designed for general use with a greater degree of protection than Type 1 or Type 2.
NEMA 12K Rating: NEMA 12K enclosures are similar to Type 12, but include pre-constructed knockouts to accommodate cables, antennas and other equipment.
NEMA 13 Rating: NEMA 13 enclosures are similar to Type 12, but include additional protection against oil and coolant seepage.
The manufacturer of your intended enclosure should have clear, easy to find coding on their website and in their literature. If you have questions about an enclosure or are unsure of its rating, you cannot assume it will meet required codes.
Remember that an IP Code might be relative to a NEMA Code, but you cannot assume so. See our IP to NEMA conversion guide for more information, as well as our guides to common IP and NEMA questions such as NEMA 4 vs. IP65. When a NEMA Code is required to meet standards, you must use an enclosure that is authentic and correct in its grouping.
The best way to assess an enclosure’s NEMA or IP compliance is always to look for UL certification. Polycase has all of our enclosures tested by UL to ensure compliance with IP and NEMA standards.
By paying attention to the capabilities and requirements of your project, you can easily find the right enclosure for the job and ensure the safety and reliability of the product and its end user. Polycase is always happy to help our customers find just the right NEMA enclosure type for them. Call us at 1-800-248-1233 or contact us online for more information.