It is a standard from IEC 60529 (International Electrotechnical Commission).
Ingress Protection code (IP Code) – which defines an enclosure rating. The IP Code reflects the degree of protection as IP followed by 2 digit numbers.

The 1st digit ranges from 0 to 6, reflecting in degrees the level of protection against the solid particles.
The 2nd digit ranges from 0 to 9 and indicates the protection against the water ingress.
First digit – Solid protection level.
0 | No protection | – |
1 | Protection against solid objects > 50 mm, such as a hand | |
2 | Protection against solid objects > 12.5 mm, such as a finger | |
3 | Protection against solid objects > 2.5 mm, such as tools | |
4 | Protection against solid objects > 1.0 mm, such as wire or small screws. | |
5 | Dust resistant, limited protection from the ingress of dust, ingress of dust not sufficient to cause harm. 2 to 8 hours. | |
6 | Dust-tight, total protection from the ingress of dust 2 to 8 hours. |
Second digit – Water protection level.
0 | No protection | |
1 | Protection against vertically dripping water, some ingress permitted | |
2 | Protection against dripping water with enclosure tilted up to a 15° angle | |
3 | Protection against spraying water | |
4 | Protection against splashing water. | |
5 | Protection against jets of water directed at the enclosure. | |
6 | Water or heavy seas, Protection against powerful jets shall not enter in harmful quantities. | |
7 | Protection against effects of immersion in water up to 1 m for a period of 30 minutes. | |
8 | Protection against effects of immersion in water up to 3 m for long periods. | |
9 | Protection against high pressure and temperature water jet |
Equivalent IP ratings:
NEMA Enclosure type number. | IEC Classification. |
1 | IP 10 |
2 | IP 11 |
3 | IP 54 |
4 | IP56 |
4 X | IP66 |
6 | IP 67 |
12 | IP 52 |
13 | IP 54 |