According to EN 60529 (VDE 0470-1):2014-09
First code number
Against penetration of solid foreign bodies:
Against access to dangerous parts with:
0
(not protected)
1
≥ 50 mm diameter
Back of hand
2
≥ 12.5 mm diameter
Finger
3
≥ 2.5 mm diameter
Tool
4
≥ 1.0 mm diameter
Wire
5
Dust-proof
6
Dust-tight
IP ratings of casings – first code number
Second code number
Vertical dripping
Dripping (15° inclination)
Spray water
Splash water
Water jet
Strong water jet
7
Temporary immersion
8
Continuous immersion
9
High-pressure and high water jet temperature