Crane Power Line Clearance: The Distances OSHA Requires

Key Takeaways

• Treat every power line as energized until the utility says it is deenergized and visibly grounded at the site.
• The first test is 20 feet. If the crane, load line, or load could get closer, the employer must pick one of three options.
• Table A allows 10 feet only up to 50 kV, and only after the voltage is known.
• Over 350 kV up to 1,000 kV, that 20-foot trigger becomes 50 feet.
• If the crane contacts a line, the operator stays in the cab. Leave only for fire or another emergency.
• Tag lines near a line have to be non-conductive. A dedicated spotter is not the signal person from the last lift.

Crane power line clearance starts at 20 feet. If the boom, load line, or load could get closer, OSHA gives three choices. Guessing the voltage is not one of them.

The rule is 29 CFR 1926.1408. It covers equipment operations near lines up to 350 kV. The load, the rigging, and the load line count. The boom is not the only part that can close the gap.

The 20-foot check comes before Table A

Before the crane moves, the employer marks the work zone. That can be flags or a range limit. Or it can be the full circle of the crane’s maximum radius.

Then ask one question. Could any part of the crane, line, or load get within 20 feet of a power line?

If the answer is no, you still assume the line is hot. You do not drift closer because the pick looks easy.

If the answer is yes, there are three legal options:

Option	What has to be true	When crews use it
Deenergize and ground	The utility confirms the line is deenergized and visibly grounded at the site	The only way to work inside the clearance
20-foot clearance	No part of the crane, line, or load gets inside 20 feet	Voltage is unknown, or you do not want to wait on Table A
Table A clearance	The utility states the voltage, and you hold that row’s distance	You need less than 20 feet, and the line is 50 kV or under

The utility has two working days to give the voltage if you use Table A. Until that number arrives, you do not get the shorter distance. You hold 20 feet.

Lines are also presumed uninsulated. A coating on the wire is not insulation unless the utility or a qualified engineer says it is.

Table A, once you know the voltage

Table A is the minimum clearance by voltage. These numbers are for alternating-current lines. The distance is to the crane, the load line, and the load, including rigging.

Voltage	Minimum clearance
Up to 50 kV	10 feet
Over 50 kV to 200 kV	15 feet
Over 200 kV to 350 kV	20 feet
Over 350 kV to 500 kV	25 feet
Over 500 kV to 750 kV	35 feet
Over 750 kV to 1,000 kV	45 feet
Over 1,000 kV	The utility or a qualified engineer sets it

A neighborhood distribution line is often under 50 kV. That row is 10 feet. You only use 10 feet after the utility confirms the voltage. A transmission line on the edge of a highway job can blow past 200 kV. That row is 20 feet or more.

For lines over 350 kV up to 1,000 kV, replace each 20-foot trigger with 50 feet. The work-zone question gets bigger. So does the warning line.

Nothing goes under a power line unless the utility has deenergized it and grounded it at the site. There is a narrow exception if the fully raised boom still sits more than the required distance below the line. Do not invent that gap from the cab. Measure it.

What the operator has to see

Inside the 20-foot problem, the crew meets before the pick. The meeting covers where the line is and how you will stay clear.

Someone puts up an elevated warning line, barricade, or flagged signs where the operator can see them. They sit at 20 feet, or at the Table A distance if that option is in use.

The employer also picks at least one more control. A proximity alarm. A range limiter. A device that stops the boom. An insulating link between the load line and the load. Or a dedicated spotter in constant contact with the operator.

A dedicated spotter judges the clearance. That person needs a visual aid and a spot where the gap is visible. They also need a way to reach the operator in time. If the operator cannot see the warning line, a spotter is required along with one of those other controls.

This is not the same job as calling the load. The signal person from the crane lift communication piece directs the pick. The power-line spotter watches the wire. Do not stack both jobs on one distracted person when the line is the hazard.

Tag lines, if you use them, must be non-conductive. A wet rope or a steel line is a path.

If the crane touches the line

Training for this is mandatory for the operator and the crew. The rule is specific about contact.

Stay in the cab. Touching the machine and the ground at the same time is how people get killed after a strike. The ground around the crane can be energized too. That is step potential. Crew members stay off the crane and off the load.

Leave the cab only if there is an imminent danger of fire, explosion, or another emergency. The exit has to be the safest way off a machine that may still be hot. Jump clear. Do not climb down in contact with the steps and the dirt at once.

Alarms and insulating links have limits. The standard says the crew has to be trained on those limits. A beep is not a smaller clearance distance.

On the Sun Prairie yard, the habit is the same one a road job needs. Find the line before you swing. Ask the voltage. Hold 20 feet until someone with authority says a shorter Table A row applies. Mobile crane training is where that check gets practiced, before a live wire is the thing in the mirror.

Want that practice before a boom sits next to a line? Check training dates, apply online, or call ATS at (800) 383-7364.

Frequently Asked Questions

Q: How close can a crane get to a power line? A: Start at 20 feet. If any part of the crane, load line, or load could get closer, the employer must deenergize and ground the line, hold 20 feet, or use Table A after the utility states the voltage. Up to 50 kV, Table A is 10 feet.

Q: What if nobody knows the voltage? A: Hold 20 feet. The utility has two working days to provide the voltage if you want Table A. Until then, the shorter distances are not available. Assume the line is energized and uninsulated.

Q: What should the operator do if the crane hits a power line? A: Stay in the cab unless fire, explosion, or another emergency forces you out. Do not touch the crane and the ground at the same time. Everyone else stays away from the crane and the load.

Q: Is the power-line spotter the same as the signal person? A: No. The spotter’s job is the clearance to the line. The signal person directs the load. OSHA allows a dedicated spotter when you are working inside the clearance problem, and requires one if the operator cannot see the warning line.