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###### May 1995

###### DHHS (NIOSH) Publication Number 95-108

#### Note: This publication supercedes 85-111

#### On this Page

                      - Background
                      - FACE Data
                      - OSHA Data
                      - Current Standards
                      - ANSI Standard
                      - CSA Recommendations
                      - Case Reports
                      - Conclusions
                      - Recommendations
                      - References

# Preventing Electrocutions of Crane Operators and Crew Members Working Near Overhead Power Lines

**WARNING!** Crane operators and crew members may be electrocuted when they work near overhead power lines.

The National Institute for Occupational Safety and Health (NIOSH)requests assistance in preventing electrocutions of crane operatorsand crew members working near overhead power lines.  Recent NIOSHinvestigations suggest that employers, supervisors, and workers maynot be fully aware of the hazards of operating cranes near overheadpower lines or may not implement the proper safety procedures forcontrolling these hazards.  This Alert describes five cases (sixelectrocutions) that resulted from such hazards and makesrecommendations for preventing similar incidents.  The Alertupdates a previous NIOSH Alert published in July 1985 [NIOSH 1985].

The recommendations in this Alert should be followed by allemployers, managers, supervisors, and workers in companies that usecranes or similar boomed vehicles.  NIOSH requests that thefollowing individuals and organizations bring this Alert to theattention of workers who are at risk:  editors of trade journals,safety and health officials, construction companies, unions,suppliers and manufacturers of building materials, cranemanufacturers, electric utilities, and others who use cranes orboomed vehicles.

Workers are killed each year when cranes contact overhead power lines.

### Background

Data from the NIOSH National Traumatic Occupational Fatalities(NTOF) Surveillance System indicate that electrocutions accountedfor approximately 450 (7%) of the 6,400 work-related deaths frominjury that occurred annually in the United States during theperiod 1980-89 [NIOSH 1993a]. Each year an average of 15electrocutions were caused by contact between cranes or similarboomed vehicles and energized, overhead power lines. The actualnumber of workers who died from crane contact with energized powerlines is higher than reported by NTOF because methods forcollecting and reporting these data tend to underestimate the totalnumber of deaths [NIOSH 1993a]. More than half of thesecrane-related electrocutions occurred in the construction industry.

### FACE Data

From 1982 through 1994, NIOSH conducted 226 onsite investigationsof work-related electrocutions under the Fatality Assessment andControl Evaluation (FACE) Program.  Twenty-nine (13%) of theseincidents (which resulted in 31 fatalities) involved crane contactwith overhead power lines. Nearly half of the incidents occurred inthe construction industry. Because the FACE investigations wereconducted in only 16 states, these fatalities represent only aportion of the crane-related electrocutions during the period1982-94.

### OSHA Data

A study conducted by the Occupational Safety and HealthAdministration (OSHA) showed that 377 (65%) of 580 work-relatedelectrocutions occurred in the construction industry during theperiod 1985-89 [OSHA 1990].  Nearly 30% (113) of theseelectrocutions involved cranes.

### Current Standards

#### OSHA Regulations

Current OSHA regulations require employers to take precautions whencranes and boomed vehicles are operated near overhead power lines.Any overhead power line shall be considered energized unless theowner of the line or the electric utility company indicates that ithas been de-energized and it is visibly grounded [29 CFR 1926.550(a)(15)(vi)]. The OSHA regulations are summarized as follows:
              - Employers shall ensure that overhead power lines are de-energizedor separated from the crane and its load by implementing one ormore of the following procedures:  De-energize and visibly ground electrical distribution and      transmission lines [29 CFR 1910.333(c)(3); 29 CFR 1926.550(a)(15)]     Use independent insulated barriers to prevent physical contact with      the power lines [29 CFR 1910.333(c)(3); 29 CFR 1926. 550(a)(15)]     Maintain minimum clearance between energized power lines and the      crane and its load [29 CFR 1910.333(c)(3)(iii); 29 CFR      1926.550(a)(15)(i), (ii), (iii)]. 
              - Where it is difficult for the crane operator to maintain clearanceby visual means, a person shall be designated to observe theclearance between the energized power lines and the crane and itsload [29 CFR 1926.550(a)(15)(iv)].
              - The use of cage-type boom guards, insulating links, or proximitywarning devices shall not alter the need to follow requiredprecautions [29 CFR 1926.550 (a)(15)(v)].  These devices are not asubstitute for de-energizing and grounding lines or maintainingsafe line clearances.

### ANSI Standard

The American National Standards Institute (ANSI) has published astandard for mobile and locomotive cranes that includes operationnear overhead power lines [ANSI 1994].  This consensus standard(B30.5-1994) contains guidelines for preventing contact betweencranes and electrical energy. The standard addresses the followingissues:
              - Considering any overhead wire to be energized unless and until theperson owning the line or the utility authorities verify that theline is not energized
              - De-energizing power lines before work begins, erecting insulatedbarriers to prevent physical contact with the energized lines, ormaintaining safe clearance between the energized lines and boomedequipment
              - Limitations of cage-type boom guards, insulating links, andproximity warning devices
              - Notifying line owners before work is performed near power lines
              - Posting warnings on cranes cautioning the operators to maintainsafe clearance between energized power lines and their equipment

### CSA Recommendations

The Construction Safety Association of Ontario, Canada (CSA)recommends safe work practices in addition to those addressed inthe OSHA and ANSI standards [CSA 1982]. These recommendationsinclude the following.

#### Work Practices

              - Operate the crane at a slower-than-normal rate in the vicinity ofpower lines.
              - Exercise caution near long spans of overhead power lines, sincewind can cause the power lines to sway laterally and reduce theclearance between the crane and the power line.
              - Mark safe routes where cranes must repeatedly travel beneath powerlines.
              - Exercise caution when travelling over uneven ground that couldcause the crane to weave or bob into power lines.
              - Keep all personnel well away from the crane whenever it is close topower lines.
              - Prohibit persons from touching the crane or its load until a signalperson indicates that it is safe to do so.

The CSA recommendations also address the limitations of proximitywarning devices, hook insulators, insulating boom guards, swinglimit stops, nonconductive taglines, ground rods, and similardevices for protection against electrical hazards.

#### Procedures to Follow If Contact Occurs

To protect against electrical shock injury in the event of contactbetween a crane and an energized line, the CSA recommends thefollowing:
              - The crane operator should remain inside the cab.
              - All other personnel should keep away from the crane, ropes, andload, since the ground around the machine might be energized.
              - The crane operator should try to remove the crane from contact bymoving it in the reverse direction from that which caused thecontact.
              - If the crane cannot be moved away from contact, the operator shouldremain inside cab until the lines have been de-energized.

### Case Reports

The five cases presented here were investigated by the NIOSH FACEProgram between March 1990 and March 1993.

#### Case No. 1--One Death

On March 1, 1990, a 29-year-old worker was electrocuted when hepushed the crane cable on a 1-yard cement bucket into a 7,200-voltpower line. The victim was a member of a crew that was constructingthe back concrete wall of an underground water-holding tank at asewage treatment plant. Before work on the tank began, the companysafety director made sure that insulated line hoses were placedover sections of the power line near the jobsite and that a safeclearance zone was marked off for arriving cement trucks to use forloading their cement buckets.

After the wall was poured, the driver of the cement truck cleanedthe loading chute on his truck with a water hose mounted on thetruck. As he began to pull away, the crew supervisor yelled to him,asking if the crew could use his water hose to wash out the cementbucket suspended from the crane. The driver stopped the truck underthe power line and the crane operator (not realizing that the truckhad been moved) swung the boom to position the bucket behind thetruck. The victim grasped the handle of the bucket door and pusheddown to open it, bringing the crane cable into contact with thepower line. The victim provided a path to ground and waselectrocuted [NIOSH 1990b].

#### Case No. 2--One Death

On August 11, 1990, a 33-year-old well driller was electrocutedwhen a metal pipe lifted by a truck-mounted crane contacted a12,000-volt overhead power line. The victim and a coworker wererepairing a submersible pump for a water well at a privateresidence. The well was located in a pasture with three parallelpower lines overhead. One of the power lines passed directly overthe well (32 feet above the ground). On the day of the incident,the victim positioned the truck-mounted crane beneath the powerline. Using a handheld remote-control pendant, the victim fullyextended the end of the boom 36 feet above the ground. The cranecable was attached to a 1-inch-diameter galvanized pipe that ran tothe pump inside the well. As the victim raised the pipe, itcontacted the power line directly above the well, energizing thecrane and the handheld remote-control pendant. The victim provideda path to ground and was electrocuted [NIOSH 1990c].

#### Case No. 3--One Death

On August 22, 1990, a 24-year-old foreman for a telecommunicationscompany was electrocuted when he grabbed the door handle on atruck-mounted crane whose boom was in contact with a 7,200-voltoverhead power line. The foreman and three other workers (alineman, a cable splicer, and a laborer) were attempting to removefour poles that had supported a billboard. The poles stood 20 feethigh and were buried 5 feet in the ground.  They were located 15feet away from (and parallel to) the power line. To remove thepoles, the lineman positioned the crane directly under the powerline. He controlled the crane boom while standing on the groundusing rubber-coated hand controls mounted on the back of the truck.The poles were removed by hooking the crane boom cable around themiddle of each pole and vertically pulling each pole out of theground. While the workers were pulling out the third pole, the endof the boom contacted the overhead power line. The laborer (who wasworking in the back of the truck) noticed that the lineman wasbeing shocked and was unable to let go of the hand control. Thelaborer kicked the lineman in the chest and the lineman fellunconscious to the ground. He revived without assistance about 3minutes later with electrical burns to his left hand. However, thecrane boom remained in contact with the power line, the truck tiresignited, and the truck began to burn. When the foreman noticed thatthe boom remained in contact with the power line, he tried to openone of the truck doors (presumably to move the truck). When hishand contacted the door handle, he provided a path to ground andwas electrocuted [NIOSH 1990a].

#### Case No. 4--One Death

On June 24, 1991, a 37-year-old construction laborer waselectrocuted while pulling a wire rope attached to a crane cabletoward a load.  The choker was to be connected to a steel roofjoist that was to be lifted 150 feet across the roof of a one-storyschool and set in place.  The cab of the crane was positioned 11feet 6 inches from a 7200-volt power line. After a previous roofjoist had been set in place, the crane operator swung the craneboom and cable back toward the victim, who grabbed the choker inhis left hand. With his right hand, he held onto a steel rod thathad been driven into the ground nearby. At this point, the momentumof the swinging crane apparently caused the crane cable to contactthe power line. The electrical current passed across the victim'schest and through the steel rod to ground, causing hiselectrocution [NIOSH 1991].

#### Case No. 5--Two Deaths

On March 31, 1993, a 20-year-old male truck driver and his70-year-old male employer (the company president) were electrocutedwhen the boom of a truck-mounted crane contacted a 7,200-voltconductor of an overhead power line. The incident occurred whilethe driver was unloading concrete blocks at a residentialconstruction site. The driver had backed the truck up the steeplysloped driveway under a power line at the site and was using thecrane to unload a cube of concrete blocks. The company presidentand a masonry contractor watched as the driver operated the craneby a handheld remote-control unit. The driver was having difficultyunloading the blocks because the truck was parked at a steep angle.While all three men watched the blocks, the tip of the crane boomcontacted a conductor of the overhead power line and completed apath to ground through the truck, the remote control unit, and thedriver. The company president attempted to render assistance andapparently contacted the truck, completing a path to ground throughhis body. He died on the scene. The truck driver was airlifted toa nearby burn center where he later died as a result of electricalburns [NIOSH 1993b].

### Conclusions

These case reports indicate that some crane operators, theiremployers and supervisors, and others who work around cranes maynot be fully aware of the hazards of operating cranes near overheadpower lines or may not implement the proper safety procedures forcontrolling these hazards.

### Recommendations

NIOSH recommends that employers take the following measures toprotect workers and operators of cranes and other boomed vehiclesfrom contacting energized overhead power lines.

#### Comply with OSHA Regulations

              - Train workers to comply with current OSHA regulations. Theseregulations require workers and employers to consider all overheadpower lines to be energized until (1) the owner of the lines or theelectric utility indicates that they are not energized, and (2)they have been visibly grounded [29 CFR 1910.333 (c)(3); 29 CFR1926.550(a)(15)].
              - Employers shall ensure that overhead power lines arede-energized or separated from the crane and its load byimplementing one or more of the following [29 CFR1910.333(c)(3); 29 CFR 1926.550(a)(15)]:                      - De-energize and visibly ground electrical distribution and      transmission lines at the point of work
                - Use insulated barriers that are not a part of the crane to prevent      contact with the lines
                - If the power lines are not de-energized, operate cranes in the area ONLY if a safe minimum clearance is maintained as follows:                        - At least 10 feet for lines rated 50 kilovolts or below
                  - At least 10 feet plus 0.4 inch for each kilovolt above 50                  kilovolts; or maintain twice the length of the line                   insulator (but never less than 10 feet) 
              - Where it is difficult for the crane operator to maintain safeclearance by visual means, designate a person to observe theclearance and to give immediate warning when the crane approachesthe limits of safe clearance [29 CFR 1926.550(a) (15)(iv)].
              - Do not use cage-type boom guards, insulating links, or proximitywarning devices as a substitute for de-energizing and groundinglines or maintaining safe clearance [29 CFR 1926.550(a)(15)(v)].

#### Follow ANSI Guidelines

Train workers to follow ANSI guidelines for operating cranes near overhead power lines (ANSI Standard B30.5-1994, 5-3.4.5)[ANSI 1994]. These guidelines recommend posting signs at the operator's station and on the outside of the crane warning that electrocution may occur if workers do notmaintain safe minimum clearance that equals or exceeds OSHA requirements as follows:

#### Notify Power Line Owners

Before beginning operations near electrical lines, notify theowners of the lines or their authorized representatives and providethem with all pertinent information:  type of equipment (includinglength of boom) and date, time, and type of work involved. Requestthe cooperation of the owner to de-energize and ground the lines orto help provide insulated barriers. NIOSH encourages employers toconsider de-energization (where possible) as the primary means ofpreventing injury from contact between cranes and power lines.

#### Develop Safety Programs

Develop and implement written safety programs to help workersrecognize and control the hazards of crane contact with overheadpower lines.

#### Evaluate Jobsites

Evaluate jobsites before beginning work to determine the safestareas for material storage, the best placement for machinery duringoperations, and the size and type of machinery to be used.

Know the location and voltage of all overhead power lines at thejobsite before operating or working with any crane.

Research has shown that it is difficult to judge accurately thedistance to an overhead object such as a power line [Middendorf1978]. Therefore, NIOSH recommends that no other duties orresponsibilities be assigned when workers are designated to observeclearance during crane movement or operation.

#### Evaluate Alternative Work Methods

Evaluate alternative work methods that do not require the use ofcranes. For example, it may be possible to use concrete pumpingtrucks instead of crane-suspended buckets for placing concrete nearoverhead power lines. Alternative methods should be carefullyevaluated to ensure that they do not introduce new hazards into theworkplace.

#### Train Workers

Ensure that workers assigned to operate cranes and other boomedvehicles are specifically trained in safe operating procedures. Also ensure that workers are trained (1) to understand thelimitations of such devices as boom guards, insulated lines, groundrods, nonconductive links, and proximity warning devices, and (2)to recognize that these devices are not substitutes forde-energizing and grounding lines or maintaining safe clearance.Workers should also be trained to recognize the hazards and useproper techniques when rescuing coworkers or recovering equipmentin contact with electrical energy.  CSA guidelines list techniquesthat can be used when equipment contacts energized power lines [CSA1982] (see Current Standards in this Alert).

All employers and workers should be trained in cardiopulmonaryresuscitation (CPR).

#### Call for Help

Ensure that workers are provided with a quick means of summoningassistance when an emergency occurs.

#### Develop Safer Equipment

Encourage the manufacturers of cranes and other boomed vehicles toconsider developing truck-mounted cranes with electrically isolatedcrane control systems, such as those that use fiber opticconductors to transmit control signals.

### Acknowledgments

The principal contributor to this Alert is Paul H. Moore, Divisionof Safety Research.  Please direct any comments, questions, orrequests for additional information to the following:

DirectorDivision of Safety ResearchNational Institute for Occupational Safety and Health1095 Willowdale RoadMorgantown, WV 26505-2888Telephone, (304) 285-5894; or call 1-800-35-NIOSH (1-800-356-4674).

We greatly appreciate your assistance in protecting the health ofU.S. workers.

Linda  Rosenstock, M.D., M.P.H.Director, National Institute for  Occupational Safety and HealthCenters for Disease Control and Prevention

### References

ANSI [1994].  American national standard for mobile and locomotivecranes. New York, NY: American National Standards Institute, ANSIB30.5-1994.

CFR. Code of Federal regulations.  Washington, DC: U.S. GovernmentPrinting Office, Office of the Federal Register.

CSA (Construction Safety Association) [1982]. Mobile crane manual.Toronto, Ontario, Canada: Construction Safety Association ofOntario.

Middendorf L [1978]. Judging clearance distances near overheadpower lines. In: Proceedings of the Human Factors Society, 22ndannual meeting. Santa Monica, CA: Human Factors Society, Inc.

NIOSH [1985]. NIOSH Alert: request for assistance in preventingelectrocutions from contact between cranes and power lines. Cincinnati, OH: U.S. Department of Health and Human Services,Public Health Service, Centers for Disease Control, NationalInstitute for Occupational Safety and Health, DHHS (NIOSH)Publication No. 85-111.

NIOSH [1990a]. Foreman electrocuted and lineman injured aftertruck-mounted crane boom contacts 7,200-volt overhead power line inVirginia. Morgantown, WV: U.S. Department of Health and HumanServices, Public Health Service, Centers for Disease Control,National Institute for Occupational Safety and Health, FatalAccident Circumstances and Epidemiology (FACE) Report No. 90-39.

NIOSH [1990b]. Laborer touching suspended cement bucketelectrocuted when crane cable contacts 7,200-volt power line inNorth Carolina. Morgantown, WV: U.S. Department of Health and HumanServices, Public Health Service, Centers for Disease Control,National Institute for Occupa- tional Safety and Health, FatalAccident Circumstances and Epidemiology (FACE) Report No. 90-29.

NIOSH [1990c]. Well driller electrocuted when pipe on crane cablecontacts 12,000-volt overhead power line in Virginia. Morgantown,WV: U.S. Department of Health and Human Services, Public HealthService, Centers for Disease Control, National Institute forOccupational Safety and Health, Fatal Accident Circumstances andEpidemiology (FACE) Report No. 90-38.

NIOSH [1991]. Construction laborer is electrocuted when crane boomcontacts overhead 7,200-volt power line in Kentucky.  Morgantown,WV: U.S. Department of Health and Human Services, Public HealthService, Centers for Disease Control, National Institute forOccupational Safety and Health, Fatal Accident Circumstances andEpidemiology (FACE) Report No. 91-21.

NIOSH [1993a]. Fatal Injuries to workers in the United States,1980-1989: a decade of surveillance. Cincinnati, OH:  U.S.Department of Health and Human Services, Public Health Service,Centers for Disease Control and Prevention, National Institute forOccupational Safety and Health, DHHS (NIOSH) Publication No.93-108.

NIOSH [1993b]. Truck driver and company president electrocutedafter crane boom contacts power line--West Virginia. Morgantown, WV:U.S. Department of Health and Human Services, Public HealthService, Centers for Disease Control and Prevention, NationalInstitute for Occupational Safety and Health, Fatality Assessmentand Control Evaluation (FACE) Report No. 93-14.

OSHA [1990]. Analysis of construction fatalities--the OSHA database1985-1989. Washington, DC:  U.S. Department of Labor, OccupationalSafety and Health Administration.

95-108sum.pdf (Worker/Employer Summary Sheet Only)   [PDF - 373 KB]

 

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