Lockout/Tagout

Even when systems have been de-energized, the possibility of re-energizing the equipment while work is being performed presents a serious hazard. Lockout/tagout procedures ensure that re-energizing electrical systems is impossible while workers are still operating in the area.

Changes made to the 2021 NFPA 70E manual specifies that these procedures must meet the requirements of applicable codes, standards, and regulations for lockout and tagging of electrical equipment.

Equipment that is de-energized but not reinforced through a lockout and tagout system is still considered "live." Employers must train each person who could be exposed directly or indirectly to a source of electrical energy in the lockout and tagout process.

Though different levels of complexity for a lockout/tagout system are appropriate for different applications, the basic principle is the same and applies to fixed, permanently installed equipment, temporarily installed equipment, and portable equipment. For lockout, a locking mechanism disables the use of switches or other devices that would re-energize the equipment, and each worker working on the equipment affixes a lock to the locking mechanism. Unless all at-risk workers have left the area and removed their locks, the equipment cannot be restored to an active state. Qualified workers verify that the equipment cannot be re-energized before work begins. Labels accompanying the locking mechanism contain information describing the reason for the lockout and the relevant hazards presented by the deactivated equipment.

A lockout/tagout is deemed "complex" if one or more of the following conditions exist:

• Multiple energy sources
• Multiple crews
• Multiple crafts
• Multiple locations
• Multiple employers
• Unique disconnecting means
• Complex or particular switching sequences
• Lockout/tagout for more than one shift

A complex lockout requires a written procedure before work begins. All on-site employees must be notified before implementing a lockout and before re-energizing the affected electrical components.

Tagout procedures are limited to informative labels that indicate electrical work is being completed. These have been found by OSHA to be less effective than lockout procedures. However, this procedure can serve a secondary purpose of helping to identify those who may have been the victim of an incident.

To learn more about Arc Flash Safety visit our OSHA Construction Arc Flash Safety Online Training web page.