4.3.1 Fixed guards

Fixed guards can always be used when the access to the danger zone is not required during the normal operation. These include protective fences, barriers, fixed covers, etc. Fixed guards are also frequently used in combination with optoelectronic protective devices as supplementary protective devices.

EN ISO 12100 requires that fixed guards must be firmly held in their place with constructive measures:

  • either permanently (e.g. welded)
  • or with fixing elements (nuts, bolts) that require the use of a tool. If possible, it should not be possible to keep them in the protective position after the fixing elements have been loosened.
  • or position-monitored with the control-connected safety switches so that the dangerous movement is blocked with the removal of the protective device (see EN 1088).

Height and safety distances of fixed guards

EN ISO 13857 "Safety of machinery - Safety distances to prevent danger zones being reached" contains two tables for dimensioning the height and required safety distance of fixed hard guard protective devices in accordance with the height of the point of operation. Table 1 contains dimensioning recommendations for hazards with low risk; table 2 contains measurement recommendations for applications with high risk.