OSHA 29 CFR 1910.147 — Control of Hazardous Energy (Lockout/Tagout) — Compliance Brief
Record covered: manufacturing-reg-002 Issuing body / enforcer: US Occupational Safety and Health Administration (OSHA), Department of Labor. Jurisdiction: US federal general industry; state-plan states enforce equivalents. (Construction has no direct LOTO equivalent — 1926 Subpart K and equipment-specific rules cover parts of the ground.) Status: Longstanding regulation; consistently in OSHA's annual Top 10 most-cited standards (typically #5–#6 in recent fiscal years, including 2026 enforcement data per catalogue notes).
1. What it is
1910.147 is the lockout/tagout (LOTO) rule: the procedural discipline that ensures machines are isolated from all energy sources — electrical, mechanical, hydraulic, pneumatic, chemical, thermal, gravitational/stored — before employees service or maintain them where unexpected energization or startup could injure them. It is the direct answer to one of industry's oldest fatality patterns: the machine that "wasn't supposed to start."
2. Scope — who and what it applies to
General-industry employers whose employees service or maintain machines and equipment where hazardous energy exists. Three employee roles: authorized (perform the lockout), affected (operate or work near the equipment), and other (everyone else in the area — must know the program exists). Key boundaries:
- Applies to servicing and maintenance, not normal production operations (production safeguarding is Subpart O's territory — see companion brief).
- Cord-and-plug exemption: equipment whose only hazard is unplugging a cord under the exclusive control of the servicing employee is exempt — but only if that single condition is fully met.
- Minor servicing exception (1910.147(a)(2)(ii)): routine, repetitive, integral-to-production adjustments are exempt only if alternative effective protection is provided — the most litigated sentence in the standard; treat it narrowly.
- Agriculture, construction, and maritime are excluded from 1910.147 (covered elsewhere or not at all).
3. Key requirements and compliance obligations
- Written energy-control program — the documented procedures for each machine/equipment type: how each energy source is identified, isolated, locked, dissipated (bleed lines, discharge capacitors, block elevated parts), and verified (try-start).
- Machine-specific procedures: generic plant procedures are not enough — each distinct machine or equipment group needs its own documented sequence. Auditors ask for these first.
- Lockout vs. tagout: locks are the required default; tags alone are permitted only if they provide protection equivalent to locks, which in practice means additional safety measures and is hard to defend. One lock per authorized employee — no group shortcuts without a formal group-lockout procedure.
- Training: authorized, affected, and other employees each get role-specific training, with retraining on job/equipment/procedure changes.
- Periodic inspection of the energy-control procedure at least annually — 1910.147(c)(6) — performed by an authorized employee other than the one using the procedure, with documented certification. This is the element most programs let lapse, and inspectors know it.
- Shift/personnel-change continuity and contractor-notification procedures (host employer must inform outside contractors of LOTO procedures and vice versa).
4. Penalties / consequences (2026 figures, verified)
OSHA maximums: $16,550 per violation (serious); $165,514 willful/repeated. LOTO citations routinely stack — one inspection commonly yields the missing program, missing machine-specific procedures, missing training, and missing annual inspections as separate violations. Because the standard is Top-10 most-cited, inspectors arrive knowing exactly where programs fail. Fatality investigations involving unexpected energization frequently produce willful characterizations and criminal referrals. Civil exposure: LOTO failures are a staple of wrongful-death and amputation litigation.
5. Version and edition status — live changes
The regulatory text is stable; the live action is in consensus practice and enforcement focus. ANSI/ASSP Z244.1 (Control of Hazardous Energy) is the current consensus companion — recent editions address alternative methods (e.g. trapped-key interlocking, guard-locking) and the minor-servicing question in more detail than the 1989-era regulatory text. Employers implementing modern LOTO should align with the current Z244.1 alongside 1910.147. Flag: no OSHA rulemaking to update 1910.147's text was identified as of September 2026; always verify against the current CFR.
6. Related certifications
- Industrial/Systems — PE Industrial & Systems (industrial-systems-cert-010); Manufacturing — PE Industrial and Systems (manufacturing-cert-012): the engineers who most often own plant energy-control programs.
- Manufacturing — SME Certified Manufacturing Engineer (CMfgE) (manufacturing-cert-001): covers equipment safety and maintenance practices including LOTO concepts.
- Industrial/Systems — Lean Bronze/Silver/Gold (industrial-systems-cert-006): SMED/quick-changeover work is exactly where minor-servicing-exception disputes arise — lean practitioners must keep LOTO compliance inside the kaizen.
3b. Stored energy, alternative methods, and the Z244.1 companion
The fatalities that 1910.147 fails to prevent are disproportionately stored-energy events: the capacitor bank that wasn't discharged, the elevated ram that wasn't blocked, the pressurized accumulator that wasn't bled, the spring under tension nobody mapped. Your machine-specific procedures must enumerate every energy source including stored and residual — walk the machine with maintenance, don't write the procedure from the OEM manual alone. On alternative methods: technologies like trapped-key interlocking (key exchange forces a safe sequence) and guard-locking with safe-stop monitoring can satisfy the standard's performance language if the risk assessment shows they achieve equivalent protection — ANSI/ASSP Z244.1's current edition gives the accepted methodology for that equivalence argument. But an alternative method without a documented risk assessment is just an unguarded shortcut with extra hardware. And remember the boundary: LOTO governs servicing; normal production operations with exposed hazards are a guarding (Subpart O) problem, and robot cells add the R15.06/10218-2 layer — the three regimes meet at the cell, so the cell's safety file should show all three.
7. Flags and honest caveats
- "Top 10 most-cited" placement is verified in pattern terms (LOTO has held a top-10 slot for years); the exact FY2026 rank was not re-pulled for this brief.
- The minor-servicing exception is the highest-risk interpretation call in the standard — when in doubt, lock it out. Compliance officers and ALJs read the exception narrowly.
Original ETS reference writing, verified against public sources on 2026-09-30. Thin sourcing is flagged inline. Not legal advice — confirm current editions with the issuing body.