Electrocutions caused by a crane, load, or load line contacting a power line have caused numerous fatalities. To prevent such accidents from occurring in the future, the standard contains detailed, systematic procedures that employers must follow when operating cranes near power lines.
These procedures are designed to:
NOTE: Special rules apply to work covered by 29 CFR, Subpart V, Power Transmission and Distribution. This course does not cover Subpart V work.
Two employees were attaching a crane lifting beam to the inside of a 10-foot-diameter precast concrete drywell section located at the front end of a flat-bed trailer. This trailer was parked under a 7600-volt overhead power line which was about 27 feet above the ground. The truck crane, a 30-year-old unit with a 35-foot boom, was located over 10 feet away from the power line. The crane’s holding line was attached to the lifting beam. The closing and tag lines were attached to the clamshell bucket positioned on the ground. The crane operator swung his boom with the lifting beam toward the two men standing atop the concrete ring. Employee #2 was at the tractor end, and employee #1 was opposite him. Both were in contact with the lifting beam ends inside the concrete ring. When employee #2’s arm got warm, he looked up and saw an arc. The crane operator swung the boom away from the power line. However, employee #1 fell back, electrocuted. The crane operator said the sun was in his eyes.
Keeping a safe distance from power lines is the key to preventing power line accidents. Therefore, the first step you must take when planning to operate a crane on a site where a power line is present is to identify the crane's work zone and use that work zone to determine how close it could come to the power line. If you determine that no part of the crane, load, or load line could get closer than 20 feet to a power line, no further precautions are required. If the initial plan for the crane's use changes during the project, you must re-evaluate whether the equipment could get closer than 20 feet to the power line.
Note: If the line's voltage is more than 350,000 volts, a 50-foot, rather than 20-foot, minimum clearance must be maintained. This course assumes the voltage is less than 350,000 volts and uses the 20-foot clearance distance.
There are two ways to identify the work zone and use it to determine whether the equipment could get closer than 20 feet to the power line. First, if the equipment (crane, load, load line, or rigging) could not get closer than 20 feet to the line even if the crane is operated at its maximum working radius, the 20-foot requirement is satisfied. Alternatively, you may establish a work zone by establishing boundaries (using flags or a device such as a range limit device or range control warning device) that are more than 20 feet from the power line and prohibiting the operator from operating the equipment past those boundaries.
Alternative to 20-Foot Clearance (Table A)
If you know the line’s voltage, you may use the minimum clearance distance in Table A below in lieu of 20 feet.
|Table A- Minimum Clearance Distances|
(nominal, kV, alternating current)
|Minimum clearance distance (feet)|
|up to 50||10|
|More than 50-200||15|
|More than 200-350||20|
|More than 350-500||25|
|More than 500-750||35|
|More than 750-1,000||45|
|More than 1,000||established by the utility owner and/or operator or registered professional engineer who is a qualified person|
One way to determine the line’s voltage is to ask the line's owner or operator. The utility must respond to such a voltage inquiry within two working days.
If you use Table A in the previous tab to determine the minimum clearance distance, you must determine whether any part of the crane, load or load line could get closer than the Table A distance to a power line if the equipment is operated up to its maximum working radius in the work zone.
If you determine that part of the crane, load, or load line could come closer to the power line than the required minimum clearance distance (either 20 feet or the Table A clearance), you must either de-energize and ground the line or take specified steps to maintain the required minimum clearance distance. These options will now be discussed.
De-energizing and visibly grounding the line will protect against electrocution and avoid the need for additional precautions. However, the employer must rely on the owner or operator of the power line’s to take these steps. Utilities are generally unwilling to de-energize their lines because doing so will cut off service to their customers. As a result, this precaution will usually not be available. You must assume all power lines are energized unless the utility owner/operator confirms the power line has been, and continues to be, de-energized, and the line is visibly grounded at the worksite.
You must take all of the following steps.
In addition, you must use at least one of the following precautions:
An employer should ensure a dedicated spotter meets the following:
No part of the equipment, load line, or load (including rigging and lifting accessories) is allowed below a power line unless:
The diagram to the right illustrates a simple solution related to power-line safety under 1926.1408.
The demarcation boundary, along with prohibiting the operator from going beyond the boundary, fulfills the requirements for power line safety in 1926.1408.
If the equipment contacts a power line, death or injury may be avoided if the workers in and on the crane know and understand the steps they can take to protect themselves. In general, the crane operator and any other person on the crane will be safe as long as they remain on the crane. The greatest danger is faced by a person who simultaneously touches both the crane and the ground, but a person who is near, but not touching, the crane can also suffer electric shock.
To ensure employees have the information they need to protect themselves, you must train each operator and crew member assigned to work with the equipment on how to avoid electrocution in the event the equipment contacts a power line. Such training must include:
The precautions described above for crane operations must also be taken when assembling or disassembling a crane near a power line. Under no circumstances may a crane be assembled or disassembled beneath an energized power line.
|Table T-Minimum Clearance Distances While Traveling With No Load|
(nominal, kV, alternating current)
|While Traveling – Min. Clearance Distance (ft.)|
|up to 0.75||4|
|More than .75 to 50||6|
|More than 50 to 345||10|
|More than 345 to 750||16|
|More than 500-750||16|
|More than 750-1,000||20|
|More than 1,000||determined by the utility owner or registered professional engineer who is a qualified person with respect to electrical power transmission and distribution|
In determining whether the equipment will maintain the required clearance distance, you must take into account the effects of speed and terrain on the equipment's movement (including movement of the boom/mast). In addition, if any part of the equipment can get closer than 20 feet to the line, you must use a dedicated spotter to observe the clearance and signal the operator in order to keep the required minimum clearance.
In some circumstances, it is impossible to perform a required lift while staying the required minimum distance from a power line. The standard provides a limited exception for such circumstances that allow operations closer than the minimum distance. However, it requires additional precautions due to the extreme danger of operating so close to a power line.
Before using this exception, you must determine that specific work required to complete the project cannot be performed while maintaining the Table A clearance.
In making this determination, you must consider whether an alternative method of performing the lift, such as repositioning the crane or the load, will enable you to maintain the required minimum distance. If you have decided that it is necessary to operate closer than the required minimum distance, you must consult the utility that owns or operates the line to determine whether it is feasible to de-energize and ground or relocate the line.
Only if de-energizing/grounding or relocation is not feasible, may you operate closer to an energized line than the minimum distance given in Table A. In such a case, you must take the following precautions to protect workers.
You must have the power line owner/operator or a registered professional engineer who is a qualified person with respect to electrical power transmission and distribution determine the minimum clearance distance that must be maintained to prevent electrical contact in light of the on-site conditions.
The factors that must be considered in making this determination include, but are not limited to:
You must hold a planning meeting with the utility owner/operator (or registered professional engineer who is a qualified person with respect to electrical power transmission and distribution) to determine the procedures to prevent electrical contact and electrocution.
The procedures required by the standard and any additional procedures developed at the planning meeting must be followed. The following procedures are required by the standard and must be followed without exception:
You, along with the utility owner/operator (or registered professional engineer) and all other employers involved in the work, must identify one person who will direct the implementation of the procedures. That person must have the authority to stop work at any time to ensure safety.
The danger of operating a crane close to a power line cannot be overemphasized. Procedures that may appear adequate at the beginning of a job may not be adequate in practice. For example, if electricity arcs from the line to the equipment, whatever precautions are being taken is not sufficient. Therefore, if there is any indication the procedures being followed are inadequate to protect workers, you must safely stop operations and either develop new, more protective procedures or have the utility owner/operator de-energize and visibly ground or relocate the power line before resuming work.
Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.
Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.