Compliance & Safety

OSHA electrical lockout tagout quiz: check your energy control skills

Q: When does OSHA 29 CFR 1910.147 apply versus OSHA electrical standards like 1910 Subpart S?

1910.147 applies when employees perform servicing or maintenance and an unexpected energization/startup or release of stored energy could cause injury. Subpart S (electrical) requirements still matter for electrical safety design and safe work practices, but 1910.147 is the standard that governs hazardous energy control during service/maintenance (procedures, locks/tags, training, inspections, and restoration).

Q: Can someone remove another employee’s lock if the job is “done”?

Normally, only the employee who applied the device removes it . Removing someone else’s lock is allowed only under a tightly controlled employer-directed process that is documented in the energy control program and includes verification that the authorized employee is not available, that they are informed before resuming work, and that the removal is recorded. If your site can’t produce that procedure and training record, it’s a serious program gap.

30 Questions 15 min

Focused on OSHA’s Control of Hazardous Energy standard, 29 CFR 1910.147, this quiz checks whether your electrical isolation steps prevent unexpected energization during servicing. Misapplied lockout/tagout is a frequent citation driver, with serious violations up to $16,550 and willful/repeat up to $165,514 per violation. Use the scenarios to validate written procedures, zero-energy verification, and group lock control.

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Lockout tagout procedure - padlock on rotary disconnect switch

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1What does the acronym LOTO stand for?

2Under OSHA regulations, what is the regulatory citation for the Lockout/Tagout standard?

3A tag by itself provides a warning but does not physically prevent equipment operation.

True / False

4Who is considered an "authorized employee" under LOTO regulations?

5In OSHA’s seven-step energy control procedure, which step comes immediately after isolating the energy sources?

6OSHA requires periodic (at least annual) inspections of energy control procedures for authorized employees.

True / False

7Before servicing a machine, what is the best first action to reduce the risk of missing a hazardous energy source?

8Which action best supports zero-energy verification on an electrical circuit after isolation?

9Which device is preferred for securing an energy-isolating device during lockout?

10Which of the following is a required component of an OSHA-compliant energy control program?

11A tagout device provides the same level of physical restraint as a lockout device.

True / False

12Arrange these actions in the correct order for isolating equipment using an energy control procedure (do not include re-energizing).

Put in order

1Isolate energy sources

2Release/secure stored energy and verify isolation

3Notify affected employees

4Shut down the equipment

5Apply lockout/tagout devices

6Prepare for shutdown (identify energy sources)

13After applying locks to a motor disconnect, you press the start button and nothing happens. What is the best next step to complete zero-energy verification for electrical hazards?

14A packaging line includes a conveyor, a pneumatic pusher, and a heater. Select all that apply: which energy sources should be considered during LOTO planning?

Select all that apply

15What minimum information should a lockout/tagout tag communicate to be most effective?

16If equipment is unplugged, no further lockout actions are needed because the plug is already disconnected.

True / False

17During shutdown of a hydraulic press, you isolate the hydraulic supply but the ram can still drop due to gravity. What step addresses this hazard before servicing begins?

18A technician locks out the main electrical disconnect on a machine but forgets about a capacitor bank in the VFD. Which hazard was missed?

19Select all that apply: which practices improve the effectiveness of lockout/tagout devices and identification?

Select all that apply

20Zero-energy verification can include attempting to start the equipment (test-firing) while maintaining a safe position.

True / False

21In a group lockout, when multiple authorized employees are involved, how should locks be applied?

22OSHA electrical safe work practices under Subpart S generally apply when exposed energized parts operate at or above what voltage (as a common threshold)?

23In a group lockout, multiple authorized employees will work inside a guarded cell. Which method best ensures each worker maintains personal control of the lockout?

24Arrange the safest sequence for verifying absence of voltage with a meter on an electrical panel.

Put in order

1Put on required PPE and use a properly rated meter

2Re-test the meter on a known live source

3Test the meter on a known live source

4Test the target circuit for absence of voltage

25A machine has been shut down and isolated. Select all that apply: which actions support controlling stored or residual energy before work begins?

Select all that apply

26You lock out a 480V motor circuit and verify zero volts phase-to-phase, but you do not check phase-to-ground. What is the main risk?

27Select all that apply: which situations commonly indicate hidden or secondary energy sources that should be checked during LOTO?

Select all that apply

28Arrange these steps for returning equipment to service after maintenance.

Put in order

1Ensure guards are reinstalled and employees are clear

2Notify affected employees and restore energy

3Remove LOTO devices by the employees who applied them

4Inspect the work area and remove tools

29A contractor is servicing a machine that has both electrical power and a pressurized hydraulic accumulator. The contractor opens the electrical disconnect, applies a lock, and begins loosening hydraulic fittings. What is the most critical procedural gap?

30A night shift takes over a job mid-maintenance on a locked-out system. Select all that apply: which controls help prevent an unsafe shift-change during group LOTO?

Select all that apply

Frequent Electrical LOTO Failures That Trigger Incidents (and OSHA Citations)

Electrical lockout/tagout failures are rarely “one big mistake”—they’re usually small breaks in sequence or documentation that defeat the energy control system. These are the patterns that show up in audits, incident investigations, and missed quiz questions.

Assuming “OFF” equals “isolated”

Mistake: Using pushbuttons, HMIs, E-stops, or control relays as the isolation point.
Fix: Isolate at an energy isolating device (e.g., disconnect switch, breaker with lockable means) that physically prevents energization.

Skipping stored-energy controls (especially capacitors)

Mistake: Opening a disconnect but not discharging capacitors, bleeding down DC bus, or controlling UPS/backfeed sources.
Fix: Identify and neutralize all stored energy sources, then verify they remain at a safe state for the duration of the work.

Weak or missing verification of zero energy

Mistake: “Try-start” only, or meter checks without a proper method.
Fix: Verify isolation using equipment-appropriate checks (e.g., absence-of-voltage testing at expected points, then attempt start where applicable).

Tagout used like lockout

Mistake: Using a tag by itself when a lock is feasible, or treating a tag as a physical restraint.
Fix: Use lockout when the device is lockable; use tagout only when lockout is not possible and the program includes equivalent protection measures.

Group LOTO and shift changes handled informally

Mistake: One “lead” lock protects multiple workers, or locks are removed before the next shift applies theirs.
Fix: Use a group lockbox or equivalent so each authorized employee applies/removes their personal lock under a controlled handoff process.

Program gaps: procedures, audits, and training

Mistake: Generic procedures that don’t match the machine, or missing periodic inspections and retraining triggers.
Fix: Keep machine-specific written procedures, perform periodic inspections, document corrective actions, and retrain when changes or deviations occur.

OSHA 1910.147 Electrical Energy Control Quick Reference (Printable)

Printable note: You can print this page or save it as a PDF for use during pre-job planning and procedure reviews.

Core terms that show up in procedures and audits

Authorized employee: Applies/controls LOTO to service or maintain equipment.
Affected employee: Operates/uses the equipment or works in the area and must be notified.
Energy isolating device: Mechanical device that physically prevents energy transmission/release (not a control circuit device).

Electrical LOTO: service/maintenance sequence (practical field order)

Prepare: Identify all energy sources (utility, generators, UPS, capacitors/DC bus, backfeed paths, control power). Confirm the correct disconnect/breaker and labeling.
Notify: Inform affected employees of shutdown and LOTO status.
Shut down: Stop the machine using normal stopping procedure.
Isolate: Open the disconnect/breaker(s) that isolate the hazardous energy. Don’t rely on E-stops or selector switches as isolation.
Apply LOTO: Each authorized employee applies a personal lock and completed tag (identity, date, reason per site practice). Use a lockbox for group LOTO.
Control stored energy: Discharge capacitors, bleed down DC bus, block/relieve mechanical potential if present, and secure any possibility of re-accumulation.
Verify zero energy: Confirm isolation at the point of work (e.g., absence of voltage where exposure exists) and attempt start when applicable and safe.

Restoring power (don’t improvise this step)

Inspect: Tools removed, guards reinstalled, covers secured, components intact.
Account for people: Everyone safely positioned; affected employees informed of re-energization.
Remove LOTO: Only the person who applied a lock removes it, unless a documented exception procedure is followed.
Re-energize in a controlled manner: Close disconnect(s)/reset breaker(s) per procedure and monitor for abnormal conditions.

Program checkpoints that commonly appear on quizzes

Written procedures must be machine/equipment-specific when required and actually used in the field.
Periodic inspections must be performed and documented for energy control procedures.
Tagout-only requires proof of equivalent employee protection when lockout is not feasible.

Electrical LOTO Decision Drills: What Would You Do at the Disconnect?

Use these short drills like pre-job briefs. For each scenario, state (1) the correct isolation point(s), (2) what gets locked/tagged and by whom, and (3) how you will verify a zero-energy state before hands-on work.

Scenarios

VFD cabinet work: You open the main disconnect feeding a VFD panel. The drive display is dark, but you know the DC bus can hold a charge. What stored-energy step(s) are required before removing the drive cover?
Two sources, one machine: A machine has a 480V supply for motors and a separate 120V control transformer fed from a different panel. How do you prevent “control power surprise” during troubleshooting?
Backfeed risk: A conveyor line is tied into a common bus that can be energized from another section. What isolation method prevents re-energization from the adjacent system?
Group maintenance: Three electricians and two mechanics will work on one machine. How do you structure group LOTO so each worker maintains personal control and nobody relies on a supervisor’s lock?
Shift change handoff: Day shift has the equipment locked out, but the task will continue into night shift. What is the correct lock removal/addition sequence so the machine is never unprotected?
Temporary energization for testing: The procedure requires briefly energizing to verify rotation after wiring changes. What sequence keeps workers protected when locks must be temporarily removed?
Cord-and-plug tool: A bench grinder is cord-and-plug connected. Under what conditions can unplugging control the hazardous energy, and what additional step prevents someone from plugging it back in?
Someone else’s lock: A lock is left on a disconnect and the employee is not on site. What must exist in the program before anyone removes that lock, and what documentation should be created?

Five High-Impact OSHA Electrical LOTO Takeaways (1910.147)

Lock at the isolating device, not the control device: An E-stop or HMI “OFF” does not substitute for isolating hazardous electrical energy at a disconnect/breaker with a lockable mechanism.
Every authorized employee needs personal control: Group lockboxes (or equivalent) prevent the “one lock protects many” failure mode and make shift-change handoffs auditable.
Stored electrical energy is still hazardous energy: Capacitors, DC bus, UPS systems, and potential backfeed paths must be identified, controlled, and included in verification.
Verification is a step, not a feeling: You should be able to explain exactly how you proved zero energy at the point of work (and why that method fits the equipment).
Programs fail on paperwork–field mismatch: Machine-specific procedures, periodic inspections, and retraining triggers matter only if they reflect how work is actually performed on the floor.

Electrical LOTO Glossary: Terms You Must Use Precisely on OSHA 1910.147

Authorized employee: The employee who locks/tags out equipment to perform servicing or maintenance. Example: “An authorized employee applies a personal lock to the disconnect before opening the MCC bucket.”
Affected employee: An employee who operates or uses the equipment or works in the area and must be notified about LOTO. Example: “Affected operators are told the line is locked out before maintenance begins.”
Energy isolating device: A mechanical device that physically prevents the transmission or release of energy (not a pushbutton, relay, or software control). Example: “A lockable disconnect switch is an energy isolating device; a start/stop station is not.”
Lockout device: A device that uses a positive means (typically a lock) to hold an energy isolating device in a safe position. Example: “A breaker lockout keeps the breaker handle in the open position.”
Tagout device: A prominent warning device attached to an energy isolating device to indicate it must not be operated until removed by the authorized employee. Example: “A tag identifies who applied control and why, but it does not physically restrain the switch.”
Stored (residual) energy: Energy that remains after isolation, such as charged capacitors, pressurized lines, or gravity potential. Example: “After opening the disconnect, the DC bus capacitor must be discharged before work.”
Verification (zero-energy check): The step where the authorized employee confirms isolation and controlled stored energy before exposure to hazards. Example: “Verification includes confirming absence of voltage at the point of work and validating the machine won’t start.”
Group lockout: A method that provides the same level of protection as personal lockout when multiple employees are involved, typically using a lockbox. Example: “Each electrician applies their personal lock to the lockbox hasp.”

Authoritative OSHA/NIOSH References for Electrical LOTO (1910.147)

OSHA Standard 29 CFR 1910.147 — The Control of Hazardous Energy (Lockout/Tagout)Official regulatory text and paragraphs commonly tested (procedures, training, inspections, group LOTO, temporary removal for testing).
OSHA Fact Sheet: The Control of Hazardous Energy (Lockout/Tagout)Quick, practical overview you can align to your facility’s written energy control procedures.
OSHA Directive STD 01-05-019 — Inspection Procedures & Interpretive Guidance for 1910.147How compliance officers evaluate LOTO programs during inspections.
NIOSH: Conducting a Periodic Inspection for Each LOTO ProcedureBest practices for the annual periodic inspection requirement and documentation expectations.
OSHA PenaltiesCurrent maximum penalty amounts to understand the enforcement stakes when LOTO programs are deficient.

OSHA Electrical Lockout/Tagout (LOTO) FAQ: Definitions, Exceptions, and Edge Cases

When does OSHA 29 CFR 1910.147 apply versus OSHA electrical standards like 1910 Subpart S?

1910.147 applies when employees perform servicing or maintenance and an unexpected energization/startup or release of stored energy could cause injury. Subpart S (electrical) requirements still matter for electrical safety design and safe work practices, but 1910.147 is the standard that governs hazardous energy control during service/maintenance (procedures, locks/tags, training, inspections, and restoration).

Is “tagout only” ever acceptable for electrical equipment?

Tagout can be used only when the energy isolating device is not capable of being locked out and the employer can demonstrate that the tagout system provides full employee protection equivalent to lockout. In practice, that means you should expect additional protective measures (equipment changes, blocking, removal of an isolating element, or other controls) and documentation that proves equivalency—not just a tag hung on a handle.

What’s the correct way to handle temporary energization for testing or positioning?

When you must temporarily remove LOTO to test/position equipment, the process must be controlled: clear tools and people, remove locks/tags per procedure, energize only as long as necessary, then de-energize and reapply LOTO before continuing service work. The quiz will often probe whether you keep the protection continuous and whether you re-verify isolation after the test.

Can someone remove another employee’s lock if the job is “done”?

Normally, only the employee who applied the device removes it. Removing someone else’s lock is allowed only under a tightly controlled employer-directed process that is documented in the energy control program and includes verification that the authorized employee is not available, that they are informed before resuming work, and that the removal is recorded. If your site can’t produce that procedure and training record, it’s a serious program gap.

How should group LOTO be structured so each worker has personal protection?

Group LOTO must provide protection equivalent to personal lockout. A common compliant structure is a group lockbox: the primary authorized employee places the key(s) to the isolating device locks into the lockbox, then each authorized employee applies their personal lock to the lockbox hasp. No one can access the key(s) until every personal lock is removed, which supports safe shift changes and clear accountability.

What’s the “cord-and-plug” exception and what is still required?

For equipment that is cord-and-plug connected, if unplugging the cord controls all hazardous energy and the plug remains under the exclusive control of the authorized employee performing the work, then additional lockout devices may not be required. The practical question is always: can someone else plug it back in, or is there any other stored/secondary energy source? If either is possible, treat it like a normal LOTO situation and control the risk accordingly.