It is important to emphasize that the machine guarding requirements of 29 CFR Part 1910, Subpart O standards COMPLEMENT THE REQUIREMENTS for LOTO. In some instances, an employer may avoid the requirements of the LOTO, if they ELIMINATE exposure to servicing and maintenance hazards by using machine guarding techniques compliant with those standards.
It is also important to note that some types of machine safeguarding devices do NOT adequately protect employees from energy hazards for all types of servicing and maintenance work. For example, light curtain safety devices are commonly used to prevent operators from having any part of their body in the danger zone during the operating cycle during the machine’s NORMAL PRODUCTION MODE of operation ONLY.
Other safeguarding devices, such as two-hand control devices and safety mat devices, when properly designed and applied, safeguard machine hazard areas during normal production, testing, and positioning operations as they utilize CONTROL CIRCUITRY to prevent employees from having any part of their body in the danger zone during the machine’s NORMAL PRODUCTION MODE. However, control circuit devices are NOT energy isolating devices and, as illustrated, some safeguarding techniques (described in national consensus standards) do NOT adequately protect employees from hazardous energy exposures during servicing and maintenance activities – hence this is when LOTO is applied.
Source: OSHA’s LOTO CPL