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Construction term · Glossary

LOTO (Lockout/Tagout)

Verified vs OSHA sources · 2026-10-05

Procedures that isolate and de-energize machines during servicing and maintenance so they can't unexpectedly start up or release stored energy. Lockout applies a physical lock to an energy-isolating device; tagout applies a warning tag; lockout is preferred. Important scope note: the general-industry LOTO standard, 29 CFR 1910.147, explicitly excludes construction — construction energy control is enforced under 1926.417, 1926.702(j), Subpart V, and the General Duty Clause.

29 CFR 1910.14729 CFR 1910.147(a)(1)(i)

Also known as: lockout/tagout, control of hazardous energy

LOTO (Lockout/Tagout) at a glance

  • Controls all hazardous energy — electrical, hydraulic, pneumatic, mechanical, thermal, chemical, gravity.
  • Lockout (a physical lock) is preferred over tagout (a warning tag alone).
  • The general-industry rule (1910.147) excludes construction; construction uses 1926.417/702(j) + Subpart V.
  • 1910.147 was OSHA's #4 most-cited standard in FY2025 (general industry).

In plain English

Locking a machine “off” so it can't turn on or spring back to life while someone is working on it. You shut it down, lock the power switch with your own lock, bleed off any stored energy, and prove it's dead before you reach in.

What the source says, in summary

This standard covers the servicing and maintenance of machines and equipment in which the unexpected energization or start up of the machines or equipment, or release of stored energy, could cause injury to employees.
29 CFR 1910.147(a)(1)(i)Summarized, not quoted: read the source for its operative wording.

In context

A concept governed primarily by OSHA's construction standards, 29 CFR Part 1926 — the rules that apply on jobsites rather than the general-industry 1910 set.

29 CFR 1926

Where this is written in OSHA's rules

Example

Before clearing a jam in a conveyor, an authorized worker shuts it off, locks the electrical disconnect with a personal padlock, bleeds the pneumatic line to release stored pressure, and pushes the start button to confirm nothing moves (zero-energy verification) — only then reaching into the machine.

Why it matters

Unexpected start-up and stored energy kill and amputate — which is why 1910.147 sits in OSHA's Top 10 (#4 in FY2025). Two frequent, dangerous mistakes are relying on a tag with no lock, and forgetting stored energy (springs, capacitors, raised loads, trapped pressure) after the power is off.

1910.147 (general industry) vs. construction LOTO

The famous LOTO standard, 1910.147, does not apply to construction — it excludes it in 1910.147(a)(1)(ii). Construction energy control is enforced under 1926.417, 1926.702(j), Subpart V, and the General Duty Clause. So don't market a construction program as “1910.147 compliant” without that caveat.

The lockout/tagout sequence

StepAction
1 · PrepareIdentify every energy source feeding the equipment
2 · Shut downTurn the equipment off using the normal procedure
3 · IsolateOperate the energy-isolating devices (disconnects, valves)
4 · Lock/tag outApply personal locks (and tags) to each device
5 · Release stored energyBleed, block, discharge, or restrain residual energy
6 · VerifyTest to confirm a true zero-energy state before work

LOTO (Lockout/Tagout): frequently asked questions

Does OSHA's 1910.147 lockout/tagout standard apply to construction?
No. 1910.147 is a general-industry standard and explicitly excludes construction (1910.147(a)(1)(ii)). Construction energy control is addressed by 1926.417, 1926.702(j), Subpart V (electric power), and the General Duty Clause.
What is the difference between lockout and tagout?
Lockout physically locks an energy-isolating device so it can't be operated; tagout attaches a warning tag but provides no physical restraint. Lockout is preferred; tagout alone is only acceptable when a device can't be locked and equivalent protection is provided.
Why is releasing stored energy so important?
Turning off the power doesn't remove energy stored in springs, capacitors, hydraulic/pneumatic lines, or raised loads. That stored energy can still injure a worker, so it must be bled off, blocked, or restrained and then verified at zero.

Related terms

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Governing OSHA standards

More Construction terms

29 CFR 1910

The part of Title 29 of the Code of Federal Regulations that contains OSHA's General Industry standards — the default rulebook for most American workplaces (manufacturing, warehousing, healthcare, etc.) that aren't covered by the construction, maritime, or agriculture standards. It includes core rules like Hazard Communication (1910.1200) and the permissible exposure limits (1910.1000). Several 1910 standards are cross-referenced into construction via Part 1926.

29 CFR 1926

The part of Title 29 of the Code of Federal Regulations that contains OSHA's Construction standards — the “Safety and Health Regulations for Construction.” It governs construction, alteration, and repair work, with construction-specific rules for fall protection (Subpart M), scaffolds (Subpart L), excavations (Subpart P), electrical (Subpart K), and more. Where a task isn't addressed in 1926, some general-industry (1910) standards apply by reference.

Anchor Point

The secure attachment point a personal fall arrest system (PFAS) ties off to — the “A” in the ABC of fall arrest. Under 29 CFR 1926.502(d)(15), a non-engineered anchorage must support at least 5,000 pounds per attached worker; alternatively, it can be an engineered anchorage designed and supervised by a qualified person with a safety factor of at least two.

Atmospheric Testing

Measuring the air in a confined space (or other hazardous atmosphere) with a calibrated direct-reading instrument before and during entry. OSHA requires testing in a set order — oxygen first, then flammable gases and vapors, then potential toxic contaminants — and defines the acceptable ranges: oxygen 19.5%–23.5%, flammables below 10% of the LEL, toxics below their exposure limits.

Benching

An excavation cave-in protective system that cuts the sides into a series of horizontal steps (benches), usually with vertical or near-vertical faces between levels. It's one of OSHA's accepted protective systems under Subpart P — but it is NOT permitted in Type C (the least stable) soil.

Competent Person (Excavation)

The competent person OSHA's excavation standard (Subpart P) requires on every trenching job — someone trained in soil classification and protective systems, who can identify cave-in and other hazards AND has authority to remove workers and correct problems. They must inspect the excavation daily before work starts, throughout the shift, and after any rain or event that could increase the hazard.

Confined Space

A space that is large enough for a worker to bodily enter, has limited or restricted means of entry or exit, and is not designed for continuous occupancy. If it also contains — or could contain — a serious hazard (a hazardous atmosphere, engulfment material, an entrapping configuration, or any other recognized serious hazard), it becomes a permit-required confined space (PRCS).

Controlling Employer

Under OSHA's Multi-Employer Citation Policy (CPL 02-00-124), the controlling employer is an employer with general supervisory authority over a worksite — including the power to correct safety and health violations itself or to require others to correct them. This is typically the general contractor or construction manager. A controlling employer can be cited for a hazard at the site even if none of its own employees are exposed, because it has a duty to exercise reasonable care to prevent and detect violations by the other employers on site.

Sources & verification

Reviewed by HazComFast against eCFR, OSHA.gov, NIOSH, and the Federal Register. Last reviewed 2026-10-05. This glossary is general information, not legal advice; OSHA State-Plan states (e.g. California, Michigan) may adopt stricter requirements.

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