How can a machine control system designer consider that "reasonably foreseeable human error during operation does not lead to hazardous situations"?

The obligation to consider 'reasonably foreseeable misuse' related not only to control systems but is reflected in the general principles of the "Essential Health and Safety Requirements". The term 'reasonably foreseeable misuse' means the use of machinery in a way not intended in the instructions for use, but which may result from readily predictable human behavior.

While similar principles are enunciated in other standards including EN ISO 12100, this statement is particularly onerous. The control system designer needs to be conscious of the risk assessment and the measures for risk reduction that are dependent on the control system. The ease ofuse and ergonomics of the machine interface and its relationship to the control system are critical. Studies show that the probability of a safety system being "bypassed" is proportional to the "benefit" of bypassing the system. Therefore to avoid predictable behavior of system bypass, the design of the safety system should be considered in a manner where machine operators do not benefit or gain incentive from bypassing safety systems. Intelligent safety concepts including zoned safety systems, boundary less guarding, safe mode enabling and safe monitoring of machine parameters should be considered by the control system designer.