Calculation formula for the minimum safety distance for AOPD with parallel approach with respect to reaching through (danger zone guarding):

The following calculation formula applies for applications of optoelectronic protective devices with approach direction of body parts parallel or in an angle up to 30° to the protective field level:

S = (1600 x T) + C with

C = (1200 – 0.4 x H)

C Additional distance for lower limbs. C always greater than 850 mm (arm length)
H Height of protective field above reference plane (floor).
Permissible installation heights H of a protective device with resolution d:
15 x (d – 50) ≤ H ≤ 1000 mm
Required resolution d of a protective device with installation height H:
d [mm] ≤ H / 15 + 50 mm


If H is greater than 300 mm the danger exists of room to crawl under. This must be taken into account with the risk assessment.

a = Safety distance S and DS
b = Measures to prevent access from the sides
c = Height H above the floor
d = 50 mm - maximum distance to prevent stepping behind.
If this value cannot be achieved because of the safety distance, other measures, e.g. mechanical barriers, must guarantee the required maximum distance of 50 mm. From 375 mm height above the floor 75 mm are permissible.
Fig. 4.2.1-7: Body part approach parallel or up to max 30° to the protective field level