According to standard IEC 60529 and/or DIN EN 60529

The degree of protection was specified and divided into several classes, indicated in the following way:

IP 67 (IP = International Protection + 2 indices with class of protection (see following tables)

 

1. Index

Protection against access

Protection against foreign objects

0 non-protected

non-protected

1 with the back of a hand

solid foreign objects (diameter from 50 mm)

2 with a finger

solid foreign objects (diameter from 12,5 mm)

3 with a tool

solid foreign objects (diameter from 2,5 mm)

4 with a wire

solid foreign objects (diameter from 1 mm)

5 with a wire

dust-protected (intrusion of dust not totally
prevented, but shall not cause damage to units)

6 with a wire

dust-tight (no intrusion of dust)

 

2. Index

Protection against ingress of water

0 non-protected
1 protected against water drops (vertical falling)
2 protected against water drops (drop angle up to 15°)
3 protected against  spraying water (at an angle up to 60°)
4 protected against splashing water (from any direction)
5 protected against water jets (from any direction)
6 protected against powerful water jets (flooding)
7 protected against temporary immersion in water (intrusion of water causing harmful
effects shall not be possible when the enclosure is immersed in water for 30 minutes
in 1m depth)
8 protected against permanent immersion in water (intrusion of water causing harmful
effects shall not be possible when the enclosure is continously immersed in water
under conditions which shall be agreed between manufacturer and user but which
are more severe than for numeral 7)
9K protected against water during high pressure- or stream cleaning
(numeral acc. to DIN 40050 part 9, IP-code for verhicles)