STSC Lockout/Tagout and Hazardous Energy Control — Questions and Answers
Question 1: Under OSHA construction standards, what is the FIRST step a worker must take before performing maintenance on powered equipment?
- Notify the supervisor and post a warning sign
- De-energize the equipment and apply a lockout device (Correct answer)
- Test the equipment to confirm it is functioning correctly
- Don appropriate PPE for the maintenance task
Correct answer: De-energize the equipment and apply a lockout device
OSHA's hazardous energy control requirements mandate that the equipment be fully de-energized and a lockout device applied before any maintenance or servicing begins. Notification and PPE are secondary steps that follow, not precede, isolation.
Question 2: A crew must replace a hydraulic hose on an excavator. After shutting off the engine, what additional step is REQUIRED before starting the repair?
- Post a caution cone around the excavator
- Have a second worker stand by as a safety observer
- Bleed residual hydraulic pressure and verify the zero-energy state (Correct answer)
- Switch to double-layer chemical-resistant gloves
Correct answer: Bleed residual hydraulic pressure and verify the zero-energy state
Stored hydraulic energy can cause sudden, violent movement even after the engine is off. OSHA requires that all stored energy — including hydraulic, pneumatic, spring, and gravitational — be released and verified at zero before work begins.
Question 3: When multiple authorized workers are simultaneously performing maintenance on the same piece of equipment, OSHA requires:
- Only the crew leader to apply a single lock on behalf of the group
- Each authorized worker to apply their own personal lock to the energy-isolating device or hasp (Correct answer)
- A single group tagout tag signed by all workers
- Verbal confirmation from the supervisor that the equipment is safe
Correct answer: Each authorized worker to apply their own personal lock to the energy-isolating device or hasp
OSHA group lockout procedures require each authorized employee to apply their own personal lock. No worker's safety should depend on another person's lock — each individual must be able to verify their own protection.
Question 4: A tagout device may be used WITHOUT an accompanying lockout device ONLY when:
- The maintenance task will take less than 30 minutes to complete
- The supervisor provides written authorization
- The energy-isolating device cannot physically accommodate a lock (Correct answer)
- The equipment has a single energy source
Correct answer: The energy-isolating device cannot physically accommodate a lock
Tags alone may substitute for locks only when the physical design of the energy-isolating device prevents a lock from being applied. Even then, OSHA requires additional equivalent means of protection, because a tag by itself provides no physical restraint.
Question 5: Which of the following is classified as a form of 'stored energy' that must be controlled during a lockout/tagout procedure?
- A laminated safety permit posted on the equipment
- Compressed air remaining in a pneumatic line (Correct answer)
- A grounded electrical extension cord near the equipment
- The operator's written inspection checklist
Correct answer: Compressed air remaining in a pneumatic line
Stored energy includes mechanical (springs, gravity), electrical (capacitors), thermal (steam), chemical, and pneumatic (compressed air or gas) energy. Compressed air in a pneumatic line can release suddenly and cause unexpected equipment movement or injury.
Question 6: Who is defined as an 'authorized employee' under OSHA's lockout/tagout standard?
- Any worker on the jobsite who has been briefed on the hazard
- The site safety officer who approves the permit
- A worker who applies lockout/tagout devices to control hazardous energy (Correct answer)
- The equipment manufacturer's representative
Correct answer: A worker who applies lockout/tagout devices to control hazardous energy
OSHA defines an 'authorized employee' as a person who locks out or tags out machines to perform servicing or maintenance. This is distinct from an 'affected employee,' who operates the equipment but does not perform the maintenance.
STSC Lockout/Tagout and Hazardous Energy Control
Under OSHA construction standards, what is the FIRST step a worker must take before performing maintenance on powered equipment?