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Course 820 - Crane and Derrick Safety I

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Power Line Safety

powerlines
Why is it critical all of the employees know and understand the hazards that exist with the cranes so close to the power lines?

Danger–High Voltage

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 1) prevent equipment from making electrical contact with power lines, and 2) protect workers in the event that such contact occurs.

NOTE: Special rules apply to work covered by 29 CFR, Subpart V, Power Transmission and Distribution. This course does not cover Subpart V work.

Related Subdivision CC Requirements

  • 1926.1408 – Power line safety (up to 350 kV)-equipment operations
  • 1926.1409 – Power line safety (more than 350 kV)
  • 1926.1410 – Power line safety (all voltages)-equipment operations closer than the Table A zone

Cranes and Power Lines

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.

powerlines
Cranes and Power Lines Distance
Click to Enlarge

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
Voltage
(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
Note: The value that follows “to” is up to and includes the value. For example, more than 50 to 200 means up to and including 200kV.

Cranes and Power Lines (Continued)

spotter
A dedicated spotter is one of the additional methods you may use to maintain the required minimum clearance distance.

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-Energize and Grounding

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.

Maintaining Required Minimum Clearance Distance

You must take all of the following steps.

  • Conduct a planning meeting with the crane operator and the other workers who will be in the area of the equipment or load to review the location of the power line(s), and the steps that will be implemented to prevent encroachment/electrocution.
  • If tag lines are used, they must be non-conductive.
  • spotter
    Must the spotter use equipment which enables them to communicate directly with the crane operator?
  • Erect and maintain an elevated warning line, barricade, or line of signs equipped with flags or similar high-visibility markings at the minimum clearance distance. If the operator cannot see the elevated warning line, a dedicated spotter must be used to signal the operator that the crane is passing the marked line.

In addition, you must use at least one of the following precautions:

  • a dedicated spotter (a worker whose only duty is to observe the clearance between the equipment and the line) who is in continuous contact with the operator;
  • a proximity alarm set to give the operator sufficient warning to prevent encroachment;
  • a device that automatically warns the operator when to stop movement, such as a range control warning device (such a device must be set to give the operator sufficient warning to prevent encroachment);
  • a device that automatically limits the crane's range of movement, set to prevent encroachment; and
  • an insulating link/device installed between the end of the load line and the load.

Dedicated Spotter

An employer should ensure a dedicated spotter meets the following:

  • be equipped with a visual aid (a clearly visible line painted on the ground or a clearly visible line of stanchions) to assist in identifying the minimum clearance distance;
  • be positioned to effectively gauge the clearance distance;
  • where necessary, use equipment that enables the spotter to communicate directly with the operator;
  • give timely information to the operator so that the required clearance distance can be maintained; and
  • be trained to be able to perform his/her duties effectively.

Operation Below Power Lines Generally Prohibited

No part of the equipment, load line, or load (including rigging and lifting accessories) is allowed below a power line unless:

  • The employer has confirmed that the utility owner/operator has de-energized and visibly grounded the power line at the worksite.
  • The highest point of the equipment's boom, even if completely extended and vertical, will be more than the required minimum distance from the power line.

Power Line Safety: Diagram Identifying the Work Zone

The diagram below illustrates a simple solution related to power-line safety under 1926.1408.

work zone
Power Line Safety: Diagram Identifying the Work Zone
Click to Enlarge
  • The job is a bridge replacement on a two-lane road.
  • Power lines were initially seven feet from the proposed work.
  • The construction company contacted the power company and arranged to move the 12.5kV line (north) six feet making the minimum clearance 13 feet.
  • At the same time, the power company agreed to install cross arms and hang a series of flags parallel to the power line.
  • The flags hang from the utility pole at eye level to the operator establishing the crane’s work zone.

The demarcation boundary, along with prohibiting the operator from going beyond the boundary, fulfills the requirements for power line safety in 1926.1408.

Real-World Example

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.

Employee Training

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:

work zone
The boom on this crane must be lowered to meet clearance levels to travel under the power lines.
  • information regarding the danger of electrocution if a person simultaneously touches the equipment and the ground;
  • the importance to the operator's safety of remaining inside the cab, except where there is an imminent danger of fire, explosion, or other emergency that necessitates leaving the cab;
  • the safest means of evacuating from equipment that may be energized;
  • the danger of the potentially energized zone around the equipment (step potential);
  • the need for crew in the area to avoid approaching or touching the equipment and the load;
  • safe clearance distance from power lines;
  • the limitations of an insulating link/device, proximity alarm, and range control (and similar) device, if used; and
  • how to properly ground equipment and the limitations of grounding.

Assembling a Crane Near a Power Line

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
Voltage
(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.

Limited Exception to Mandatory Minimum Clearance

deenergize
If you operate closer than the required minimum distance, you must consult the utility company to determine if it is feasible to de-energize and ground or relocate the line.

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.

Determine an Absolute Minimum Clearance

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:

meeting
To prevent electrical contact do you need to hold a planning meeting with the utility owner/operator?
  • conditions affecting atmospheric conductivity;
  • time necessary to bring the equipment, load line, and load (including rigging and lifting accessories) to a complete stop;
  • wind conditions;
  • degree of sway in the power line;
  • lighting conditions; and
  • other conditions affecting the ability to prevent electrical contact.

Hold a Planning Meeting

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.

Use Protective Procedures

barricade
An elevated warning line, or barricade, in view of the operator must be erected. Should it also be equipped with some sort of high-visibility markings?

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:

  • If the power line is equipped with a device that automatically re-energizes the circuit in the event of a power line contact, before the work begins, the automatic reclosing feature of the circuit interrupting device must be made inoperative if the design of the device permits.
  • A dedicated spotter who is in continuous contact with the operator must be used to ensure the equipment does not breach the minimum clearance. The requirements for a dedicated spotter are discussed above.
  • An elevated warning line, or barricade (not attached to the crane), in view of the operator (either directly or through video equipment), equipped with flags or similar high-visibility markings, must be erected.
  • An insulating link/device must be installed at a point between the end of the load line (or below) and the load. Note: certain safety procedures or devices may be substituted for a Nationally Recognized Testing Laboratory-approved insulating link during an interim period. Refer to Standard 1926.1410(d)(4)(iv) and (v) of the standard for details.
  • All employees who may come in contact with the equipment, the load line, or the load (except operators located on the equipment) must be insulated or guarded by wearing insulating gloves rated for the voltage involved or using another effective means of insulating them from the equipment.
  • Nonconductive rigging must be used.
  • If the equipment is equipped with a device that automatically limits range of movement, it must be used and set to prevent any part of the equipment, load line, or load (including rigging and lifting accessories) from breaching the minimum approach distance.
  • Any tag line must be of the non-conductive type.
  • Barricades forming a perimeter at least 10 feet away from the equipment must be erected to prevent unauthorized personnel from entering the work area. In areas where obstacles prevent the barricade from being at least 10 feet away, the barricade must be as far from the equipment as feasible.
  • Workers other than the operator must be prohibited from touching the load line above the insulating link/device and crane. The operator is excluded from this requirement because while, on the equipment, the operator is, in effect, touching the load line above the insulating link/device. However, if the operator is remotely operating the equipment from the ground, he/she must use either wireless controls that isolate the operator from the equipment or insulating mats that insulate the operator from the ground.
  • Only personnel essential to the operation are permitted in the area of the crane and load.
  • The equipment must be properly grounded.
  • Insulating line hose or cover-up must be installed by the utility owner/operator except where such devices are unavailable for the line voltages involved.
  • Each operator and crew member assigned to work with the equipment must be trained in the topics listed earlier in this section.

Appoint a Project Director

barricade
If there is any indication the procedures being followed are inadequate to protect workers, you must safely stop operations. You must then either develop new procedures or de-energize the power line.

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.

Reconsider Your Plan if a Problem Arises

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.

Working Around Power Lines

Always Never
  • ALWAYS keep a safe distance of at least 10 feet between you and your equipment from the power lines.
  • ALWAYS survey the site for overhead power lines. LOOK UP!
  • ALWAYS, when using crane and/or equipment near energized power lines of 50,000 volts (50kV) or more, make sure the minimum distance between the lines and any part of the crane is 10 feet plus 4 inches for each 10kV more than 50kV.
  • ALWAYS request an observer to assist you where it is difficult to maintain the desired clearance by visible means.
  • ALWAYS require that the only job of the observer is to help the operator maintain the safe clearance.
  • ALWAYS treat overhead power lines as if they were energized.
  • ALWAYS, when in doubt, call the electric company to find out what voltage is on the lines.
  • ALWAYS ask the electric company to either de-energize and ground the lines or install insulation while you are working near them.
  • ALWAYS make sure ladders and tools are non-conductive.
  • NEVER get closer than 10 feet to an overhead power line!
  • NEVER work at a site without checking for power lines. LOOK UP!
  • NEVER, when using cranes and/or equipment near energized power lines of 50,000 volts (50kV) or more, get closer than 10 feet plus 4 inches for each 10kV over 50kV.
  • NEVER use cranes alone where it is difficult by visible means to maintain the desirable clearance.
  • NEVER forget that overhead power lines could be energized.
  • NEVER allow the observer to perform another job while helping the operator to maintain a safe clearance.
  • NEVER take a chance without consulting first with the electric company to find out what voltage the lines carry.
  • NEVER work near power lines until you are certain they have been de-energized and grounded or insulated by the electric company.
  • NEVER work with ladders and tools if they have not been rated nonconductive.

Video

Instructions

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.

Good luck!

1. What is the key to preventing power line accidents?

2. The first step you must take when planning to operate a crane on a site where a power line is present is to _____.

3. No further precautions are required if you determine that no part of the crane, load, or load line could get closer than _____ feet to a power line.

4. 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, and you cannot maintain the required minimum distance, you must _____.

5. A person who simultaneously touches both the crane and the ground faces the greatest danger; however a person who is _____ the crane can also suffer electric shock.


Have a great day!

Important! You will receive an "error" message unless all questions are answered.