Protective fences are offered with square and oblong grids.
 
The following applies to grids in the shading:
 
Square grids:
2-3 cm side length of a square opening require at least 12 cm distance to the nearest danger point
3-4 cm side length of a square opening requires at least 20 cm to the nearest danger point
 
Slotted grilles:
Grilles with side length 2 cm or smaller require at least 12 cm distance to the nearest danger point
Grilles with side length 3 cm x 6.5 cm or smaller require at least 20 cm distance to the nearest danger point
 
If you want to use an answer for your risk assessment, please buy the Standards research, check it, and also check very carefully if the given case really applies to your machine. If you have any doubts, feel free to contact me.
Please remember that there could be C- Standard specifically for your machine that contains statements on the subject. My statements refer to the B-Standards. If you provide me with your C-Standard, I will research your C-Standard on the subject.