Which method is not recognized by OSHA as a valid safeguarding method?

The chosen answer indicates that "guarding by location" is not recognized by OSHA as a valid safeguarding method. This is accurate because OSHA emphasizes the use of physical barriers, guards, or engineered solutions to protect workers from machine hazards. While location can reduce risk by placing hazardous machines in areas away from personnel, it does not actively provide protection like the other methods.

In contrast, the other options represent established and effective safeguarding measures. The use of personal protective equipment (PPE) serves as a last line of defense when hazards cannot be eliminated or controlled through other means. Machine enclosures offer protective barriers around moving parts to prevent accidental contact, while interlocks and safety devices ensure that machinery cannot operate under unsafe conditions. Each of these methods is recognized and validated by OSHA as effective in reducing the risk of injury in the workplace.