OSHA’s Subpart K electrical safety standards are the federal rules that govern electrical work on construction sites, set out at 29 CFR 1926.400 through 1926.449. They cover how equipment is designed and installed, how temporary power is run, how workers are protected from shock, how circuits are locked out and tagged, and how close anyone can get to an energized line. Electrocution is one of construction’s leading causes of death, and Subpart K exists to prevent it through enforceable requirements that apply from the first extension cord plugged in to the final tie-in.
Installation and Workspace Basics
The starting rule is simple. Every piece of electrical equipment on a construction site must be free from recognized hazards likely to cause death or serious physical harm, judged on mechanical strength, durability, and the quality of electrical insulation. Equipment carrying a listing, label, or certification has to be installed and used according to the instructions that came with that approval.1eCFR. 29 CFR 1926.403 – General requirements
Circuit breakers, switches, and overcurrent devices need clear markings identifying what they control unless their location makes that obvious. Unused openings in cabinets, junction boxes, and fittings must be sealed so foreign objects and fingers cannot reach live parts.2eCFR. 29 CFR Part 1926 Subpart K – Electrical Workspace in front of electrical equipment must be at least 30 inches wide, and depth clearances grow with voltage and with whether grounded and ungrounded parts sit on opposite sides of the space.1eCFR. 29 CFR 1926.403 – General requirements
Wiring design under 29 CFR 1926.404 forbids attaching a grounded conductor to a terminal in a way that reverses polarity, because reversed polarity can leave a tool’s casing energized while it still runs. Conductors must have enough capacity for their load, and overcurrent protection must match the conductor’s rating.3eCFR. 29 CFR 1926.404 – Wiring design and protection The path to ground has to be permanent and continuous, not something a bump or a loose connection can interrupt.2eCFR. 29 CFR Part 1926 Subpart K – Electrical
Temporary wiring gets its own treatment. It must be removed as soon as construction is complete or the specific purpose it was installed for no longer exists.4eCFR. 29 CFR 1926.405 – Wiring methods, components, and equipment for general use There is no calendar deadline; the trigger is the end of the work.
Ground-Fault Protection: GFCIs or an AEGC Program
Ground-fault protection is where most day-to-day compliance lives. Every 120-volt, single-phase, 15- and 20-ampere receptacle outlet that is not part of the building’s permanent wiring must have GFCI protection whenever employees are using it.3eCFR. 29 CFR 1926.404 – Wiring design and protection A GFCI detects current leaking through an unintended path, such as a worker’s body, and cuts the circuit in milliseconds.
The alternative is an Assured Equipment Grounding Conductor program. This is a formal option, not an informal one: the program must be written, kept on the jobsite, and available for inspection, and the employer must designate one or more competent persons to run it. Every cord set, plug, receptacle, and cord-connected piece of equipment falls under it.5eCFR. 29 CFR Part 1926 Subpart K – Installation Safety Requirements
The AEGC program has two layers. Before each day’s use, cord sets, attachment caps, plugs, and receptacles get a visual check for deformed or missing pins, insulation damage, and signs of internal damage, and anything defective stays out of service until repaired. On a scheduled cycle, every equipment grounding conductor is tested for electrical continuity, and each receptacle and plug is verified to have the grounding conductor connected to the correct terminal.
Testing has to happen before first use, before returning any repaired item to service, after any incident that could have caused damage (a cord run over by a forklift, for example), and at intervals no longer than three months. Fixed cord sets and receptacles not exposed to damage can go six months between tests.5eCFR. 29 CFR Part 1926 Subpart K – Installation Safety Requirements Each test must be recorded so that the equipment tested and the date are identifiable. Logs, color coding on plugs, or any other tracking method that actually works will satisfy recordkeeping, but the records must be on-site.2eCFR. 29 CFR Part 1926 Subpart K – Electrical Equipment that has not met these testing requirements cannot be put in workers’ hands. Citations often land on sites where the written program exists on paper but the testing logs show gaps.
Working Near Energized Circuits
Installation rules cover the equipment. Work-practice rules cover the people. Under 29 CFR 1926.416, no worker may be allowed close enough to an electric power circuit to make contact unless protected against shock, and protection means one of two things: the circuit is de-energized and grounded, or it is effectively guarded by insulation or other means.6eCFR. 29 CFR 1926.416 – General requirements
Before work starts, the employer has to determine, by inquiry, direct observation, or instruments, whether any energized circuit, exposed or concealed, is close enough to create a hazard. If one is, warning signs go up and stay up.6eCFR. 29 CFR 1926.416 – General requirements Walkways near electrical equipment cannot be used as passageways when energized parts are exposed, and barriers have to prevent that use.7eCFR. 29 CFR 1926.416 – General requirements
Task-specific PPE fills in the rest. Workers using jackhammers, bars, or other hand tools near underground power lines whose exact location is unknown must wear insulated protective gloves. When fuses have to be installed or removed while one or both terminals are energized, only tools insulated for the voltage in question can be used.6eCFR. 29 CFR 1926.416 – General requirements
Overhead Power Line Clearances
Overhead lines drive some of the deadliest incidents on construction sites, and the clearance numbers reflect it. For lines at 50 kV or less, workers in elevated positions and any conductive object they handle must stay at least 10 feet from the unguarded, energized line. Above 50 kV, the distance grows by 4 inches for every additional 10 kV. The same distances apply to workers on the ground handling conductive objects such as metal ladders or scaffolding poles.
Vehicles and mechanical equipment able to raise parts of their structure near overhead lines also have to maintain 10 feet at 50 kV or less, with the same increase at higher voltages. Equipment in transit with its structure fully lowered has a reduced clearance of 4 feet, again with voltage-based increases above 50 kV. Qualified electrical workers have their own minimum approach distances, starting at “avoid contact” for 300 volts or less and scaling up with voltage.
Lockout and Tagging
When a circuit or piece of equipment is de-energized for work, 29 CFR 1926.417 requires two things at once: the equipment must be rendered inoperative, and tags must be attached at every point where it could be re-energized.8eCFR. 29 CFR 1926.417 – Lockout and tagging of circuits Controls that need to be deactivated during work on energized or de-energized equipment must also be tagged, and the tags have to plainly identify the equipment or circuits involved.9eCFR. 29 CFR 1926.417 – Lockout and tagging of circuits A tag on a construction site says someone’s life depends on that circuit staying off. Removing or ignoring it is a serious violation.
Flexible Cords and Extension Cords
Flexible cords and cables come with a list of prohibited uses under 29 CFR 1926.405(g).4eCFR. 29 CFR 1926.405 – Wiring methods, components, and equipment for general use They cannot serve as substitutes for the fixed wiring of a structure. They cannot be run through holes in walls, ceilings, or floors, or threaded through doorways or windows, with only a narrow exception for certain temporary configurations. They cannot be fastened to building surfaces or concealed behind walls, ceilings, or floors.
Extension cords add their own restriction. They cannot be fastened with staples, hung from nails, or suspended by wire.6eCFR. 29 CFR 1926.416 – General requirements These are among the most commonly cited violations on construction sites. Damaged extension cords can be repaired and returned to service, but the repair must restore the cord to its originally approved condition, keeping the original design, capacity, materials, and construction. Splicing two different gauge cords together does not meet the standard.10Occupational Safety and Health Administration. Whether extension cords may be repaired and returned to use
Maintenance and Environmental Conditions
Equipment that was compliant on installation day does not stay compliant by itself. In hazardous locations where combustible dust, flammable gases, or ignitable fibers may be present, all wiring and equipment must remain dust-tight, dust-ignition-proof, or explosion-proof as appropriate, with every screw, gasket, threaded connection, and seal intact.11eCFR. 29 CFR 1926.431 – Maintenance of equipment
Environmental deterioration has its own rule at 29 CFR 1926.432. Unless equipment is specifically identified for the environment it sits in, it cannot be placed in damp or wet locations, exposed to gases, fumes, vapors, or other deteriorating agents, or subjected to excessive temperatures. Equipment approved only for dry locations has to be protected from the weather during construction. Metal raceways, cable armor, boxes, cabinets, and support hardware must be made of materials appropriate to the setting, such as corrosion-resistant materials in coastal or chemical-exposure environments.12eCFR. 29 CFR 1926.432 – Environmental deterioration of equipment Construction conditions shift constantly, and so does the compliance picture.
Battery Charging and Transformer Vaults
Battery charging areas carry both chemical and explosive hazards. Under 29 CFR 1926.441, unsealed batteries must be housed in enclosures with outside vents or in well-ventilated rooms arranged to keep fumes, gases, and electrolyte spray from escaping into other areas, and ventilation must be sufficient to prevent an explosive mixture of battery gases from accumulating.13eCFR. 29 CFR 1926.441 – Batteries and battery charging Quick-drenching facilities for eyes and body must be within 25 feet of the battery handling area.14Occupational Safety and Health Administration. 29 CFR 1926.441 – Batteries and battery charging Workers handling batteries or acid must have face shields, aprons, and rubber gloves. Floors must be acid-resistant or protected from acid accumulation.
Transformer vaults must be built to contain fire and combustible liquids and to prevent unauthorized entry. Locks and latches have to be arranged so the door can still be opened readily from the inside.4eCFR. 29 CFR 1926.405 – Wiring methods, components, and equipment for general use Installations inside vaults, locked rooms, or areas surrounded by controlled-access fencing count as accessible only to qualified persons, which changes but does not eliminate the protective measures required.2eCFR. 29 CFR Part 1926 Subpart K – Electrical
Qualified Persons and Training
Subpart K distinguishes qualified from unqualified persons, and the label changes what rules apply to a given worker. A qualified person under 29 CFR 1926.449 is one familiar with the construction and operation of the equipment and the hazards involved.15Occupational Safety and Health Administration. Definitions applicable to this subpart Qualified workers get closer minimum approach distances to energized parts; unqualified workers get larger safety buffers. Misclassifying someone unqualified as qualified, or failing to enforce the larger clearances for unqualified employees, is a compliance failure.
The general training mandate sits at 29 CFR 1926.21, which requires employers to instruct each employee in recognizing and avoiding unsafe conditions and in the regulations that apply to their work.16eCFR. Safety training and education For electrical work, that covers the specific hazards on the site, which protective method is in use (GFCIs or the AEGC program), lockout and tagging procedures, and the clearance distances for overhead and underground power lines. Handing a worker a manual does not satisfy the obligation.
Penalties
OSHA adjusts its civil penalties every year for inflation. Under the 2025 adjustment, the maximum penalty for a serious violation is $16,550 per violation. Willful or repeated violations run to a maximum of $165,514 per violation, with a minimum of $11,823.17Occupational Safety and Health Administration. 2025 Annual Adjustments to OSHA Civil Penalties The figures move slightly each year, so contractors should check the current schedule.
Electrical violations are among the most frequently cited in construction, and OSHA does not need an injury to issue a citation. An inspector who walks onto a site and finds damaged cords in use, missing GFCI protection, or an AEGC program with incomplete testing logs can cite on the spot. Five unprotected receptacles are five serious violations, not one.