OSHA’s minimum clearance distance from power lines is 10 feet for overhead lines carrying up to 50 kV during general construction work, and that distance grows by 4 inches for every additional 10 kV above 50 kV. Cranes and other hoisting equipment work under a stricter default: 20 feet from any line up to 350 kV, unless the voltage has been confirmed and a tighter distance from OSHA’s Table A applies. Getting these numbers wrong is one of the most common causes of electrocution on construction sites, and the penalties reflect that.
General Construction: The 10-Foot Rule
Under 29 CFR 1926.416, no employer can permit an employee to work close enough to any part of an energized power circuit to contact it, unless the circuit has been de-energized and grounded or is effectively guarded by insulation.1eCFR. 29 CFR 1926.416 – General Requirements For uninsulated, energized lines up to 50 kV, the minimum clearance is 10 feet. That applies to every person, every scaffold component, every ladder, and every piece of non-insulated material on site.
Above 50 kV, add 4 inches of clearance for each additional 10 kV.
Before work begins, the employer has to determine whether any energized circuit runs through or near the work area, using observation, employee inquiry, or instruments. If one does, warning signs go up and workers get told where the lines are, what the hazards are, and how to stay clear.1eCFR. 29 CFR 1926.416 – General Requirements
Cranes and Heavy Equipment: The 20-Foot Default
Cranes get their own, tighter rules under Subpart CC of 29 CFR 1926, because a boom or load line can swing into a line in seconds and the equipment’s reach often exceeds what the operator can visually judge.
Before operating, the employer identifies the work zone by marking physical boundaries or by treating the equipment’s full working radius as the zone. The controlling question: could any part of the equipment, load line, rigging, or load come within 20 feet of a power line up to 350 kV?2eCFR. 29 CFR Part 1926 Subpart CC – Cranes and Derricks in Construction
If yes, the employer picks one of three paths:
- Ask the utility to de-energize the line and visibly ground it at the worksite.
- Maintain the full 20-foot clearance for every part of the equipment and load.
- Confirm the line’s voltage and use the tighter minimum from Table A of 29 CFR 1926.1408.
Table A Distances by Voltage
When the voltage is known and confirmed, Table A sets the minimum clearance between any part of the equipment and the line:2eCFR. 29 CFR Part 1926 Subpart CC – Cranes and Derricks in Construction
- Up to 50 kV: 10 feet
- Over 50 kV to 200 kV: 15 feet
- Over 200 kV to 350 kV: 20 feet
If voltage is unknown, the 20-foot default holds until the utility confirms otherwise. The distances cover everything: boom, jib, load line, rigging, and load.
Encroachment Prevention
Picking a clearance number is only half the requirement. The employer must also put encroachment prevention in place to keep that distance during operations. OSHA requires at least one of the following:3Occupational Safety and Health Administration. 1926.1408 – Power Line Safety (Up to 350 kV) – Equipment Operations
- A dedicated spotter whose only job is watching clearance, in continuous contact with the operator.
- A proximity alarm or range-limiting device that warns or stops equipment before it breaches the zone.
- An elevated warning line or barricade with high-visibility markers set at the required clearance, in the operator’s line of sight.
- Non-conductive tag lines for guiding loads.
If the operator cannot see the warning line, a dedicated spotter is required regardless of what else is in place. The spotter must be positioned to gauge the gap accurately, equipped to talk directly with the operator, and cannot take on other tasks while spotting.4eCFR. 29 CFR 1926.1411 – Power Line Safety – While Traveling Under or Near Power Lines With No Load
Traveling Under or Near Lines
A separate rule applies to equipment in transit. Under 29 CFR 1926.1411, if any part of the equipment will come within 20 feet of a line while traveling with no load, a dedicated spotter is required. The whole machine, including raised booms or masts, has to stay outside that distance.4eCFR. 29 CFR 1926.1411 – Power Line Safety – While Traveling Under or Near Power Lines With No Load This is the situation contractors most often overlook: driving a crane between work areas on a site with overhead lines crossing the travel path.
Qualified Electrical Workers Use a Different Rule
The 10-foot and 20-foot distances do not apply to qualified employees building or maintaining electric transmission and distribution lines. Those workers operate under 29 CFR 1926 Subpart V and use a Minimum Approach Distance (MAD) calculated to prevent electrical flashover.5eCFR. 29 CFR Part 1926 Subpart V – Electric Power Transmission and Distribution For voltages from 5.1 kV to 72.5 kV, OSHA publishes standardized tables. Above 72.5 kV, employers have to run site-specific calculations that account for nominal system voltage, maximum anticipated transient overvoltage, and altitude. Higher elevations reduce air density and let electricity arc across wider gaps, so MAD increases with elevation.
Only qualified employees trained to recognize and avoid electrical hazards may work on or near exposed energized parts. Unqualified employees are excluded from Subpart V entirely.
When Required Clearance Cannot Be Maintained
Occasionally the work cannot be done at the required clearance and de-energizing isn’t feasible. OSHA treats this as a last resort and requires documentation that both alternatives were genuinely infeasible.
The employer must consult the utility owner or a licensed professional engineer to set a site-specific minimum clearance accounting for wind, atmospheric conductivity, and equipment stopping time. That calculated distance replaces the standard Table A number. If the line stays energized, the conductors themselves must be physically protected with insulating barriers, temporary line covers, or similar guards.
Two more requirements attach:
- A planning meeting reviewing the procedures with every worker involved, held before work starts.
- The utility owner must disable the automatic reclosing feature on circuit-interrupting devices, if the equipment allows it, so the line cannot automatically re-energize after a fault.6eCFR. 29 CFR 1910.269 – Electric Power Generation, Transmission, and Distribution
Skipping any step turns a permitted procedure into a violation. OSHA inspectors focus heavily on this documentation after an incident.
Training Before Work Begins
Clearance distances work only if people know they exist. Employers must advise employees of the location of power lines, the hazards, and the required protective measures before any work near energized circuits.1eCFR. 29 CFR 1926.416 – General Requirements
Crane operators face a specific tested competency. Under 29 CFR 1926.1427, they must demonstrate knowledge of procedures for preventing and responding to power line contact.7Occupational Safety and Health Administration (OSHA). 1926.1427 – Operator Training, Certification, and Evaluation Operators-in-training cannot run equipment where any part could come within 20 feet of a line up to 350 kV, or within 50 feet of a line over 350 kV, unless they hold full certification.
The most common failure investigators find after an incident is that workers simply weren’t told the lines were there.
If Equipment Contacts a Line
Contact still happens even with proper planning. What you do in the next few seconds decides whether it’s a close call or a fatality.
If you are inside the equipment, stay in the cab. The tires or tracks insulate you from ground, and as long as you don’t touch the machine and the ground at the same time, current has no path through your body. Call for help and wait for the utility to de-energize the line. The only reason to leave is fire or another immediate threat to your life.
If you have to exit, jump clear with both feet together. Never step down, because that puts you in contact with the equipment and the ground at the same instant. Once you land, shuffle away with small steps, feet close together, both feet touching the ground the whole time. This prevents step potential, where voltage differences between your two feet create a current path through your legs. Keep shuffling well clear of the area.
If you’re a bystander, do not approach the equipment or a downed line. The ground around an energized contact point carries voltage that drops with distance, and you can be electrocuted without ever touching anything metal. For distribution systems around 13.8 kV, a minimum safe distance of at least 22 feet from the contact point has been recommended; for 230 kV transmission lines, at least 34 feet. On wet ground, those distances roughly double.8Department of Energy Office of Health, Safety and Security. Contact With Overhead Lines and Ground Step Potential
OSHA Penalties for Clearance Violations
Electrical violations rank among OSHA’s most-cited construction hazards. A willful or repeated violation, which is how OSHA typically classifies a clearance breach where the employer knew the lines were there and did not take protective steps, carries a maximum penalty of $165,514 per violation. Failure to correct a cited hazard by the abatement deadline adds up to $16,550 per day.9Occupational Safety and Health Administration. OSHA Penalties
On multi-contractor sites, OSHA doesn’t cite only the company whose worker was hurt. Under its multi-employer citation policy, four categories of employer can be cited from the same incident:10OSHA. Multi-Employer Citation Policy
- The creating employer, whose actions caused the hazard, even if none of its own workers were exposed.
- The exposing employer, whose workers were exposed and who knew or should have known about the hazard.
- The controlling employer, typically the general contractor with supervisory authority over the site, for failing to exercise reasonable care in preventing and detecting violations.
- The correcting employer, responsible for maintaining safety equipment or fixing hazards, for failing to meet that obligation.
In practice, a power line incident can generate citations against the general contractor, the crane rental company, and the subcontractor operating the crane all at once. “It wasn’t our crane” is not a defense for a general contractor with supervisory authority who failed to ensure clearance requirements were followed.