Ingress Protection (IP) and it’s NEMA equivalent ratings

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