When looking for a specific enclosure protection rating, it is not uncommon to encounter two very popular rating systems – NEMA and IP. As common as they both are, they have their differences. Understanding them both is key to effectively navigating the different ratings, and choosing the sensor with the proper enclosure.
To be clear, the two rating systems have different criteria, and there is no way to get an exact match from one to another. The two rating systems come from two different standards: NEMA 250 and IEC 60529. As you may have guessed, IP codes come from the IEC 60529 standard, while NEMA 250 handles NEMA enclosure types.
An IP code, as specified by the IEC 60529 standard, states the degree of protection provided by an enclosure. It is very specific in purpose, and covers only three types of protection:
- Keeps people from accessing hazardous parts inside the enclosure
- Prevents the ingress of solid objects
- Protects against the ingress of water
As for sensors, the primary concerns are dust and moisture as they can damage the electronics inside the sensor housing. The IP code is made up of two digits, the first stating the protection against dusts and other solids, and the second stating the protection against water.
Here’s the IP code chart:
|First Number||Protection||Second Number||Protection|
|0||Not Protected||0||Not Protected|
|1||Objects > 50 mm diameter||1||Vertical Drops|
|2||Objects > 12.5 mm diameter||2||Drops at 15° angle|
|3||Objects > 2.5 mm diameter||3||Spraying Water|
|4||Objects > 1.0 mm diameter||4||Splashing Water|
|6||Dust-Tight||6||Powerful Water Jets|
For example, APG’s PG7 digital pressure gauge has is rated IP 67, which means it’s dust-tight, as noted by the 6 in the first digit, and can handle temporary immersion in water, identified with the 7 of the second digit.
So the big question: Is there a NEMA equivalent to IP codes? The answer is “most likely”. The NEMA enclosure type system can meet or exceed the IP code specified. However, because of differences in terminology and types of protection offered, an exact match is impossible.
The best advice is to read the requirements and be familiar with what the NEMA and IP ratings mean. Doing so will allow the proper selection of a sensor and enclosure.
We’ll be back soon with part 2 of this post, explaining NEMA enclosure types and what they mean. Once we’ve covered both standards, we’ll wrap this discussion up with a conversion chart.
Just remember that knowing your application is the most important part of the equation. These posts are aimed at helping you understand enclosure protection ratings. But without a good handle on the application, it's easy to get it wrong.