Understanding NEMA Enclosures

March 5, 2014

We had a post last week that went over what a hazardous location is and how they are classified. With today’s post, we will expound on that topic and discuss the different electrical enclosure types, what they are, and where they are used.

To begin our discussion of electrical panel enclosure, it is helpful to remember what makes things sanitary. One of the keys is that the equipment must be cleanable. This doesn’t only mean that it can be taken apart or cleaned in place. In a lot of food and beverage applications, this means that the equipment may be hosed down or subject to direct water spray. It could also mean that the enclosure is located outside or in a location classified as hazardous. Many facilities are damp, or dusty, some are even exceptionally hot or humid. All of these conditions can wreak havoc on electronics. At Holland, we’ve been helping customers select both the correct process equipment and enclosure type for over sixty years. The following is a brief overview of the types of enclosures we commonly specify for high purity applications and when they should be used.

NEMA 4X (left), NEMA 1 (right)

NEMA 4X (left), NEMA 1 (right)

The National Electric Manufacturers Association (NEMA) specifies the following enclosure types for non-hazardous locations when completely and properly installed:

Type 1 Enclosures are constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt). This enclosure is the most basic and should only be used in light duty applications. Generally, we’ll see these types of electrical enclosures used as a sub component mounted within a larger enclosure.

Type 2 Enclosures are pretty comparable to Type 1 enclosures, but are designed to provide a degree of protection against water. The water resistance is limited to light splashing. It is not designed to protect against direct spray.

Type 3 enclosures (Including 3, 3R, 3S, 3X, 3RX, and 3SX) are primarily suited for outdoor use. They are designed to prevent the ingress of water, such as rain, sleet, and snow, and also be undamaged and operate when ice laden. This enclosure type is available in high corrosion resistant types as well (3RX and 3SX).

Type 4 enclosures are much more common in high purity applications. Type 4 enclosures are constructed for either indoor or outdoor use to provide a degree of protection of the equipment inside the enclosure against the ingress of solid foreign objects; to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water. This includes rain, sleet, snow, and splashing water but is differentiated from NEMA 3 enclosures in that it is designed to guard the internal components against direct hose spray. This is a true “wash-down” enclosure.

Type 4X enclosures are probably the most common type of enclosure we specify for the harsh environments of a food or beverage process plant. A lot of times we’re coupling a wash-down duty motor with a NEMA 4X drive. The 4X duty rating is comparable to Type 4, but adds an additional corrosion resistance benefit not seen with Type 4 enclsoures.

We generally don’t see Type 5 and 6 enclosures very often in the high purity industry. Type 5 enclosure does not offer the same dust protection of Type 4 and 4X, and Type 6 is designed for occasional water submersion, also a condition we generally don’t have to satisfy.

Types 12, 12K, and 13 are designed for applications where there may be oil or coolant seepage. These are more common than full water submersion, but we still don’t specify them often.

To conclude, the enclosure type selection is critical when specifying a new piece of process equipment. Optimal enclosure selection is essential for not only maximizing equipment life, but also increasing operator safety. Remember, all of the about ratings are for Non-Hazardous Locations. Future posts will focus on the ratings for Hazardous locations, as well as considerations and constructional difference of enclosures designed for indoor/outdoor use. If you have any additional questions about which enclosure type is right for you, contact a Holland Sales Engineer today.