The international standard requires a minimum height of 1400mm. Lower fences are easy to climb over and thus not allowed. In most cases, fences will be a lot higher.
The proper height depends on two dimensions:
- The height of the danger zone above the floor (note that the highest point may be above the top edge of the planned guard fence)
- The horizontal distance from outside the fence to the danger zone
When these dimensions are known, you can read the required height of the fence from the chart which has been taken from (EN) ISO 13857. The same values are given in ANSI B11.19 Annex E and CSA ISO 13857.
Note: There are also minimum distances that must be kept from the inside of a mesh panel to the hazard zone.
Mesh grid size aperture - Safety distance
Up to a slot height of 20mm, the safety distance is ≥ 120mm.
The same applies to square openings that are no bigger than 30x30mm.
However, is the slot is more than 200mm high and 30 to 65mm wide, a greater safety distance of 200mm is needed.
If you need to go closer to the hazard from lack of space, use solid panelling.