NEMA and IP ratings are essential for selecting the right electrical enclosure because they indicate the level of environmental protection needed to safeguard equipment from dust, water, corrosion, and other hazards.
Choosing the right enclosure may seem like a simple decision until you’re deep into a project spec. The enclosure you pick determines how well your electrical components hold up against dust, water, oil, corrosion, and everything else that comes with the surrounding environment. Get it right, and your equipment can run reliably for years. Get it wrong, and you may be looking at premature repairs, costly downtime, and safety concerns.
Two primary rating systems can help guide your selection: NEMA ratings and IP ratings. Both define the level of protection that an enclosure provides for the content inside, but the ratings are derived from different standards. Learn the details of what each system entails and how to choose between NEMA enclosure ratings and IP ratings.
What Are NEMA Ratings?
NEMA ratings come from the National Electrical Manufacturers Association (NEMA) and are defined under the NEMA 250 standard. Most enclosure specifications include NEMA ratings, and many U.S. codes, specifications, and customers expect to see them.
NEMA ratings identify an enclosure’s construction type. There are many, but the most common ratings include:
- NEMA Type 1 enclosures provide a degree of protection for indoor use against incidental contact and the entry of foreign objects, such as falling dirt or dust.
- NEMA Type 3R enclosures provide weather-resistant protection for use outdoors, including protection against rain, sleet, and external ice formation.
- NEMA Type 4 enclosures are rated for use indoors or outdoors, and offer protection against external elements such as wind-blown dust, rain, and splashing water.
- NEMA Type 4X enclosures offer similar protection to Type 4 enclosures, with added protection against corrosion. They are a good choice for food processing, chemical, marine, and wastewater environments.
- NEMA Type 12 enclosures are used for indoor industrial applications, and offer protection against dust, lint, fibers, and dripping non-corrosive liquids.
What Are IP Ratings?
IP ratings, or Ingress Protection ratings, are derived from the International Electrotechnical Commission’s IEC 60529 standard. The IP system is used widely across the globe, and is common in Europe, as well as for equipment that is exported or designed for international use.
An IP rating is a two-digit designator, indicating the degree to which an enclosure is protected against dust and water.
- The first digit indicates the level of protection from the entry of solids, ranging from 0 (no protection) to 6 (dust-tight).
- The second digit indicates the level of protection from liquids, ranging from 0 (no protection) to 9 (protection against high-pressure, high-temperature water jets).
The rating designator an IP54 enclosure is “dust protected” and protected against sprayed water, while an IP67 enclosure is completely dust-tight and protected against temporary submersion.
The Primary Differences Between NEMA and IP
The simplest explanation of the difference between NEMA and IP ratings concerns their scope. An IP rating indicates only an enclosure’s level of protection from ingress in a general sense. In comparison, a NEMA rating is broader in scope and indicates the degree of environmental protection an enclosure provides beyond ingress resistance.
So, while an IP67 rating indicates that an enclosure is dust-tight and resistant to temporary submersion, it doesn’t indicate its resistance to corrosion, while an equivalent NEMA enclosure type would include specifications covering corrosion requirements.
Due to the scope of information included in NEMA enclosure ratings vs. IP enclosure ratings, a general equivalence chart can be used to identify which IP rating most closely approximates a given NEMA enclosure type. The reverse comparison cannot be made due to the lack of detail provided by an IP rating. Such equivalences indicate that a NEMA 1 enclosure approximates an IP20 enclosure, a NEMA 3R enclosure approximates an IP24 enclosure, and a NEMA 4 or 4X enclosure approximates an IP66 enclosure, while a NEMA 12 enclosure approximates either an IP54 or IP55 enclosure. A NEMA 6P enclosure approximates an IP68 enclosure.
Geographic location and industry are also determining factors in which types of enclosure ratings are used. NEMA ratings tend to be used in North America, while IP ratings tend to be used elsewhere. Projects in the U.S. will typically specify NEMA ratings while equipment in international markets may specify IP ratings. Any equipment subject to both environments should consider both standards. Certain enclosures will be rated under both standards.
How to Choose the Enclosure Rating
Once you know which rating system your project requires, the next step is determining the level of protection the enclosure needs. Some things to consider are:
- The degree to which the enclosure will be exposed to outdoor elements such as rain or snow, or indoor elements such as lint or fibers.
- The requisite to withstand harsh conditions such as washdowns or temporary submersion.
- The effects of chemical exposure, salt spray, or oils that may corrode the enclosure.
- Exposure to extreme temperatures or UV exposure.
- The effects of impact.
Other elements to consider include the requirements of the spec: some call for NEMA ratings, some for IP ratings, and some for both. Location and serviceability are also factors for enclosure selection, as mounting locations or equipment serviceability needs can influence enclosure ratings or types.
Cable entries, cutouts, windows, or mounted electrical equipment can degrade the level of protection an enclosure offers, so they must be considered in the enclosure selection process. The integrity of the enclosure is only as good as its weakest component: all components must provide the level of protection the enclosure is rated for. An experienced electrical enclosure manufacturer can work with an engineer to specify or modify an enclosure so that it’s suited to the requirements of the environment in which it will be mounted.
Why It’s Important to Choose the Correct Rating
Choosing an enclosure that is too low a rating for a demanding working environment can result in moisture gaining entrance to the equipment and causing faults or short circuits, failures due to dust accumulation, or corrosion and subsequent failure due to chemical exposure and poor maintenance.
On the other hand, choosing an enclosure that is too high a rating can add unnecessary costs to the equipment or project. The right enclosure strikes a happy medium: enough protection for its working environment, but not more than needed.
Contact Rockett Inc. to Explore Enclosure Options
Understanding NEMA and IP ratings is just the start of specifying the right enclosure. As an electrical enclosure manufacturer, Rockett Inc. works with engineers to identify the appropriate rating, enclosure type, and modifications for each application. Contact Rockett Inc. to learn more.
Frequently Asked Questions
- What is the difference between NEMA and IP ratings?
NEMA ratings define an enclosure’s construction and provide information about protection from environmental conditions such as dust, water, corrosion, and other hazards. IP ratings, based on IEC 60529, primarily indicate an enclosure’s protection against the entry of solids and liquids.
- What do the two numbers in an IP rating mean?
The first digit identifies an enclosure’s protection against solid objects and dust, ranging from 0 to 6. The second digit identifies protection against liquids, ranging from 0 to 9. For example, an IP67 enclosure is dust-tight and protected against temporary submersion.
- What are some common NEMA enclosure ratings?
Common NEMA ratings include Type 1 for basic indoor protection, Type 3R for outdoor weather protection, Type 4 for protection against wind-blown dust and water, Type 4X for similar protection with added corrosion resistance, and Type 12 for indoor industrial applications involving dust and dripping non-corrosive liquids.
- Can NEMA and IP ratings be compared directly?
NEMA and IP ratings are based on different standards and cover different levels of environmental protection, so they’re not directly interchangeable. Some NEMA types have commonly referenced approximate IP equivalents, but an IP rating does not capture every environmental requirement covered by a NEMA rating.
- How do I choose the right NEMA or IP enclosure rating?
Consider the enclosure’s location and exposure to rain, snow, dust, water, chemicals, salt spray, oil, temperature extremes, UV exposure, and impact. Project specifications may also require a particular NEMA rating, IP rating, or both. Cable entries, cutouts, windows, and other components should also be evaluated because they can affect the enclosure’s overall protection.