When should electrical controllers be locked out or tagged out?

Electrical controllers should be locked out or tagged out during maintenance and repair to ensure the safety of personnel working on or near the equipment. This practice is vital to prevent accidental energizing of the system, which can pose serious hazards such as electrical shock or even fatal injuries. The lockout/tagout procedure ensures that the equipment is completely shut off and cannot be started again until the maintenance or repair work is done and the locks/tags are removed by authorized personnel.

In the context of other options, while locking out or tagging out might be advisable during installation, system testing, or routine operation, these scenarios do not require the same level of safety precaution as maintenance and repair work. Installation typically happens under controlled conditions where the equipment is not yet operational, while system testing and routine operation generally involve active operation of the system where safety protocols can differ. The key focus of the lockout/tagout procedure is to protect workers during periods of potential equipment hazards, making maintenance and repair the most critical time for such measures.