Highly advanced production systems of robotics and automation applications involve many direct interactions between humans and machines. Ensuring an operators' safety, especially in a hazardous area, is of primary concern. As required by various international standards, including superior international standards such as ISO 12100, machine operation of human-attended operation must be controlled by using the enabling device. Three-position enabling switch is the integral component of enabling devices, and in 2006, IEC 60947-5-8 was newly published to set the requirements of three-position enabling switch. This report explains the requirement of the three-position enabling switches which play an important role in establishing the inherent safety in operating environment.