Electrical Safety and Lockout/Tagout

Why Electrocution Is on the Fatal Four

Electrocution means death caused by electricity. It is one of the Fatal Four, despite being almost entirely preventable. Most deaths come from contact with overhead power lines, contact with energized equipment or wiring, and improper use of extension cords and tools.

The governing standard is 29 CFR 1926 Subpart K (Electrical), which adopts much of the National Electrical Code. Lockout and tagging of circuits is covered by 1926.417, which requires deenergized equipment or circuits to be rendered inoperative and tagged at all points where they can be energized. The general-industry energy-control standard, 29 CFR 1910.147, states that it does not cover construction employment, but contractors widely use its procedure as their lockout practice.

GFCI vs. AEGCP: The Two Compliance Paths

Under 1926.404(b)(1), an employer must protect workers on 120-volt, single-phase, 15- and 20-ampere receptacles that are not part of the permanent building wiring by one of two methods:

1. GFCI (Ground-Fault Circuit Interrupter) protection on those receptacles, OR
2. An Assured Equipment Grounding Conductor Program (AEGCP) — a documented program of regular cord, tool, and receptacle inspection plus continuity and terminal testing.

Most contractors choose GFCIs because they are simpler and faster. The AEGCP requires color-coded tags, recordkeeping, and scheduled retesting (e.g., every 3 months).

How a GFCI saves lives

A Class A GFCI continuously compares current flowing out on the hot conductor with current returning on the neutral. If it detects an imbalance of about 4–6 milliamperes (nominally 5 mA) — meaning current is leaking to ground, possibly through a person — it trips in roughly 25 milliseconds.

Because 100 mA across the heart can be lethal, a 5 mA trip point provides a large safety margin.

Cords, Tools, and Grounding

The supervisor must enforce daily habits:

• Inspect cords before each shift (1926.416(e)) — no worn, frayed, or damaged insulation; no missing or deformed prongs.
• Never remove the third (grounding) prong.
• Keep cords out of water and away from sharp edges and hot work.
• Use only tools that are double-insulated or properly grounded.

Power-Line Clearance for Cranes and Equipment

Overhead lines kill crane crews. Under 1926.1408 Table A, any part of a crane or its load must stay at least:

• 10 feet from lines up to 50 kV.
• 15 feet from lines over 50 to 200 kV.
• 20 feet from lines over 200 to 350 kV, with greater distances at higher voltages.

Before crane work, 1926.1408(a)(2) also requires checking whether any part of the equipment, load line, or load could get within 20 feet of a line (50 feet for lines over 350 kV up to 1,000 kV, 1926.1409). Work closer than the Table A distance is prohibited unless the line is de-energized and visibly grounded or the strict conditions of 1926.1410 are met. Treat all lines as energized until verified otherwise.

Lockout/Tagout (LOTO) — Step by Step

Lockout/Tagout (LOTO) controls hazardous energy during servicing and maintenance where unexpected energization, start-up, or release of stored energy could injure a worker. Energy sources include electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and gravity (stored).

The required sequence under 1910.147:

1. Prepare — identify all energy sources and the magnitude/type of energy.
2. Notify affected employees that LOTO is about to begin.
3. Shut down the equipment by normal stopping procedure.
4. Isolate each energy source at its isolating device (breaker, valve, disconnect).
5. Lock and tag — each authorized employee applies their own lock and tag to each isolating device.
6. Release stored energy — bleed, block, or dissipate residual energy (capacitors, springs, suspended loads, hydraulic pressure).
7. Verify (Try) — confirm a zero-energy state by operating the controls and/or testing with a meter, then return controls to off.

The 'one worker, one lock' rule

Every authorized employee must apply their own lock, and only that employee may remove it. A group lockbox is used for crews. A supervisor may never cut off a worker's lock except under a strict, documented removal procedure when that worker is unavailable.

Don't forget stored energy

De-energizing the electricity is not enough. Stored energy must also be released or restrained: charged capacitors, compressed springs, pressurized hydraulic or pneumatic lines, suspended loads held by gravity, hot surfaces (thermal), and trapped steam or chemicals. A common LOTO fatality is a worker killed by a suspended ram or spring-loaded part that was never blocked, even though the power was locked out. The exam often pairs "electrical lockout" with a hidden stored-energy hazard.

Qualified vs. Unqualified Persons

A qualified person (1910.332) has training and demonstrated skill to work on or near exposed energized parts, knows the approach boundaries (limited, restricted, arc-flash), and uses proper PPE. An unqualified person must stay outside these boundaries. The exam tests this distinction directly.

Arc flash and the de-energized default

An arc flash is an explosive release of energy from an electrical fault that can reach 35,000°F and cause severe burns. OSHA's default rule is to work de-energized whenever feasible; energized work is allowed only when de-energizing introduces a greater hazard or is infeasible, and then only by a qualified person using arc-rated PPE inside the marked arc-flash boundary. The limited approach boundary keeps unqualified workers away from exposed energized conductors.

Common Mistakes

• Thinking a GFCI replaces grounding — it complements it.
• Confusing the 5 mA trip point with the 100 mA fatal current.
• Allowing one worker to remove another's lock.
• Forgetting to verify (try) zero energy before touching the equipment.
• Using less than 10 ft of clearance from a sub-50 kV line.