TL;DR: Lockout/tagout (LOTO) is OSHA’s rule for keeping machines from starting up or releasing stored energy while someone services them. In general industry it is 29 CFR 1910.147: a written energy control program, training for authorized and affected employees, a six-step shutdown sequence, and an inspection of each procedure at least once a year. Construction work falls under separate Part 1926 rules, such as 1926.417 for electrical circuits and 1926.702(j) for concrete and masonry equipment.
When I screen maintenance technicians and electricians for new battery and EV plants, almost every hiring manager asks me the same follow-up: “Can they do LOTO, and can they explain it?” Not “do they know the word.” They want someone who can walk to a mixer or a conveyor, find every energy source, lock it, bleed it down, and prove it is dead before a hand goes in.
That matters even more at a brand-new plant, where the site is switching from construction to production and two sets of OSHA rules meet. Below is what the standard actually says as of October 2026, how it plays out during commissioning, and the LOTO questions I see technicians get in interviews.
Why LOTO comes up in almost every technician interview
OSHA’s lockout/tagout fact sheet says compliance with the standard prevents an estimated 120 fatalities and 50,000 injuries each year, and that workers hurt by hazardous energy lose an average of 24 workdays to recover. The energy can be electrical, mechanical, hydraulic, pneumatic, chemical or thermal, according to OSHA’s hazardous energy overview.
It is also one of the most cited rules in the country. On OSHA’s preliminary FY2026 top 10 list (October 1, 2025 to August 31, 2026), control of hazardous energy (1910.147) ranks third. For an employer, a technician who treats LOTO casually is a real risk. For you, being solid on it is one of the easiest ways to stand out.
Which rule applies: general industry vs. construction
This is where people get confused. 1910.147 does not cover construction. Its scope section in the eCFR lists construction among its exclusions, along with agriculture, maritime, electric utility generation and distribution, and oil and gas well drilling. In a 2000 interpretation letter, OSHA said plainly that 1910.147 does not cover construction activities, and that contractors doing construction work follow the lockout and tagout provisions in Part 1926.
| Rule | Where it applies | What it requires (short version) |
|---|---|---|
| 1910.147 | Servicing and maintenance in general industry (an operating plant) | Written program, procedures, training, annual inspection, lock or tag devices, group lockout rules |
| 1926.417 | Electrical work in construction | Tag controls that are deactivated; render deenergized circuits inoperative and tag them at all points where they can be energized; tags must plainly identify the equipment or circuit |
| 1926.702(j) | Concrete and masonry equipment in construction | No maintenance or repair on equipment like compressors, mixers, screens or pumps unless all hazardous energy sources are locked out and tagged; tags read “Do Not Start” or similar |
Notice how much thinner the construction rules are. 1926.417 is about tags on electrical circuits. 1926.702(j) is one paragraph about concrete equipment. Many construction sites run a fuller lock-based program anyway as company policy, but the detailed program elements below come from 1910.147.
The energy control program: what an employer must have
Under 1910.147(c)(1), the employer must set up a program made of three parts: energy control procedures, employee training and periodic inspections. A few other rules sit on top of that:
- Lockout first. If an energy isolating device can take a lock, the program must use lockout, unless the employer can show a tag gives full employee protection. Tagout alone is for devices that cannot be locked.
- Written procedures. Each procedure must spell out its scope, purpose, authorization, rules and techniques, plus steps for shutdown, isolation, applying and removing devices, and testing to verify the machine is dead. There is a narrow eight-part exception for simple machines with a single energy source and no stored energy.
- Proper devices. Locks and tags must be durable, standardized within the facility (by color, shape or size), substantial enough that they cannot be removed without excessive force, and identifiable to the person who applied them. Tag attachments need a minimum unlocking strength of 50 pounds.
- New equipment must accept a lock. Since January 2, 1990, energy isolating devices on new, replaced, majorly repaired or modified equipment must be designed to accept a lockout device.
- Notification. Affected employees must be told before controls are applied and after they are removed.
Authorized vs. affected employees (and everyone else)
Interviewers love this question because the answer shows whether you have actually worked under a program. The standard defines three groups, and training differs for each.
| Group | Who they are | Training required by 1910.147(c)(7) |
|---|---|---|
| Authorized employee | The person who locks or tags out a machine to service or maintain it | Recognize hazardous energy sources, the type and magnitude of energy, and the methods to isolate and control it |
| Affected employee | Someone who operates or uses the machine, or works in the area where servicing is done | The purpose and use of the energy control procedure |
| Other employees | Anyone whose work may be in an area where energy control procedures are used | The procedure exists, and they must never try to restart or reenergize locked or tagged equipment |
Two details matter. Only authorized employees who are doing the servicing may apply the lockout or tagout, per (c)(8). And retraining is required when job assignments, equipment or processes change, when procedures change, or when an inspection shows gaps. The employer must certify training with each employee’s name and dates of training.
The six steps of applying energy control
1910.147(d) lists the steps in order. Memorize them. You will likely be asked to walk through them out loud.
- Preparation for shutdown. Know the type and magnitude of the energy, the hazards, and how to control it.
- Machine or equipment shutdown. Turn it off using the normal, orderly procedure.
- Isolation. Operate every energy isolating device (breakers, disconnects, valves) so the machine is cut off from its energy sources.
- Lockout or tagout device application. Each authorized employee puts on their own device.
- Stored energy. Relieve, disconnect, restrain or otherwise make safe any stored or residual energy: springs, capacitors, hydraulic or air pressure, elevated parts.
- Verification of isolation. Before starting work, confirm the machine is actually isolated and deenergized.
Step six is where interviews get real. OSHA’s 2000 letter notes verification can include a deliberate attempt to start the equipment, visual checks or test instruments, and that electrical work also requires test equipment under 1910.333. A good answer is “try to start it, then return the controls to off,” plus “test before touch” with a meter on electrical work.
Release from lockout has its own rules in 1910.147(e): clear tools, check that the machine is intact, make sure everyone is clear, tell affected employees, and have each device removed by the person who put it on. The only exception is a documented, trained procedure for when that person has left the facility, which requires real efforts to reach them before they return to work.
Annual periodic inspection and group lockout
Periodic inspection. Under (c)(6), the employer must inspect each energy control procedure at least once a year. The inspector must be an authorized employee other than the people using that procedure. The certification must list the machine, the date, the employees included and the inspector. If you have done these reviews, put it on your resume. It reads as ownership of the program, not just compliance.
Group lockout. Big equipment such as a coating line, a formation rack or a mixing system often needs several crafts at once. Under (f)(3), the group procedure must give each person the same protection as a personal lock:
- One authorized employee has primary responsibility for the crew working under the group device, for example an operations lock on a lockbox.
- That person can check the exposure status of each member.
- When more than one crew, craft or department is involved, one authorized employee coordinates overall control.
- Each authorized employee puts their own personal lock on the group device or lockbox when they start, and removes it when they stop.
The standard also requires specific procedures for shift or personnel changes so protection does not break between the off-going and incoming crew, under (f)(4). When outside contractors service equipment, the host employer and the contractor must tell each other their lockout procedures, under (f)(2).
Commissioning: the handover from construction to operations
This is where I see the most confusion on new plant projects, like a Georgia battery plant construction site moving into start-up. For months the site runs as construction. Contractors install and energize equipment under Part 1926 and the general contractor’s site rules. Then lines start running, the plant’s own maintenance team takes over, and servicing that equipment falls under 1910.147. Construction activities follow Part 1926, while servicing and maintenance on operating equipment follow 1910.147, so both can be in play on the same day in the same building.
In practice, the handover period usually means:
- Contractor locks and plant locks on the same equipment, so group lockout and the (f)(2) contractor exchange really matter.
- Machine-specific written procedures being written or finalized while equipment is still being tested.
- Equipment being energized for testing or positioning. Under (f)(1), devices can be removed temporarily only in a set order: clear the machine, remove people, remove devices, energize and test, then deenergize and relock before work continues.
- Bilingual work. Vendor technicians, HQ engineers and local crews may not share a first language, while OSHA’s fact sheet says workers have a right to training in a language and vocabulary they understand. Someone who can explain a lockbox procedure in both languages is valuable here.
If you are applying for a start-up or maintenance role at a new plant, say you understand this handover. Very few candidates mention it. I covered more of what goes wrong on these sites in lessons from battery plant construction incidents.
What’s different at Korean companies
At the Korean battery, auto and chip plants I recruit for, the LOTO program is usually written to OSHA, but the details can come from HQ standards as well. Expect equipment from Korean vendors whose manuals or labels may be partly in Korean, and commissioning teams sent from Korea for a period of months. Plants tend to ramp up fast, which means overtime and pressure to restart lines quickly. That is exactly when shortcuts happen, and why managers ask how you handle being rushed. For more on the day-to-day, see technician jobs at Korean factories and safety jobs at Korean battery and chip plants.
LOTO questions technicians get in interviews
These are the kinds of questions I hear hiring managers ask maintenance and electrical candidates. Practice answering each in under a minute.
- Walk me through how you lock out a machine before you start work on it.
- What is the difference between an authorized and an affected employee?
- What do you do about stored energy, like a hydraulic accumulator or a spring?
- How do you verify the machine is really deenergized?
- How does group lockout work with a lockbox?
- What happens at shift change if the job is not finished?
- A supervisor tells you to skip LOTO for a “quick fix.” What do you do?
- Someone’s lock is still on and they have gone home. What happens next?
For general interview prep, see my guide on Korean company interview questions. If you do not have an OSHA card yet, OSHA 10 vs OSHA 30 explains which one fits.
Questions to ask before you accept
- Are machine-specific written LOTO procedures already in place, or will I help write them?
- Who runs the annual periodic inspection, and will I be trained to do it?
- Does the company supply personal locks and tags, or do I bring my own?
- How is LOTO coordinated with contractors still on site during start-up?
- Are procedures and labels available in English, or only in another language?
FAQ
Does 1910.147 apply on a construction site?
No. Construction is excluded from 1910.147. Construction work follows Part 1926 rules such as 1926.417 and 1926.702(j), though many sites use a fuller lock program as policy.
How often must LOTO procedures be inspected?
At least once a year, by an authorized employee who is not using the procedure being inspected, with a written certification.
Can I just use a tag instead of a lock?
Only if the device cannot be locked, or if the employer can show a tag gives full employee protection. Lockout is the default.
Who can remove my lock?
You. The only exception is a documented, trained procedure for when you have left the facility, which includes trying to reach you and telling you before you return.
Is there a time limit on how long a lock can stay on?
In a November 2025 interpretation letter, OSHA said it does not specify a maximum time a lockout device may be used, for example while waiting on a part.
General information, not legal advice. Rules and interpretations can change, so check the current standard and your employer’s written program. Sources: eCFR 29 CFR 1910.147; OSHA 1926.417; OSHA 1926.702; OSHA Lockout/Tagout Fact Sheet; OSHA Control of Hazardous Energy; OSHA interpretation, Nov. 16, 2000; OSHA interpretation, Nov. 24, 2025; OSHA Top 10 Most Frequently Cited Standards.
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