RESEARCH REPORT:
SAFETY INTERVENTIONS TO
CONTROL HAZARDS RELATED TO
POWER LINE CONTACTS BY
MOBILE CRANES AND OTHER
BOOMED EQUIPMENT
FUNDED BY
THE CENTER TO PROTECT WORKERS’ RIGHTS
Suite 10008484 Georgia Ave. Silver Springs, MD 20910
301.578.8500
DEVELOPED BY
THE HAZARD INFORMATION FOUNDATION, INC.
(HIFI)
705 East Wilcox Drive Sierra Vista, AZ 85635
520.458.6700 [email protected]
TABLE OF CONTENTS List of Illustrations ii Acknowledgements iii Abbreviations iv Flow Sheet v Abstract 1 Introduction 3 Method 10 Analysis 14 Timeline Analysis 14
Critical Analysis by Engineers and Scientists 79
Results 103
Case Studies Charts 104
Standards 110
Court Transcripts 111
Expert Analysis 112
Discussion 115
System Safety Engineering 115
Eliminating the Hazard 118
Guarding Against the Hazard 122
Warning of the Hazard 124
Recommendations 130
Organizational 131
Managerial 134
Technical 136
APPENDICES
A. 50 Case Summaries and Explanatory Note 139
B. Resumes of Participating Engineers and Scientists/ Bibliography 189
PARTICIPATING ENGINEERS AND SCIENTISTS 1. David V. MacCollum: Principal Investigator
2. Rowena I. Davis: Editorial Analyst
3. Jack Ainsworth: Electronic Engineer- Proximity Alarms 4. David Baker: Safety Director, Electric Utility
5. Bob Dey: Consultant, Construction Manager
6. George Karady: Electrical Engineer- Insulating Links 7. Ben Lehman: Retired Admiral, U.S. Navy
8. Melvin L. Myers: Consulting Engineer, Retired Captain, US Public Health Service 9. Jeff Speer: Safety Director, System Safety
10. John Van Arsdel: Consultant, Human Factors
LIST OF ILLUSTRATIONS
Illustration I: Warning Label, including the proposed parameters for the mapping of the
Red Danger Zone 76
Illustration II: Danger Zone Diagram showing both overhead and lateral views 77
Illustration III: Aerial Basket Guard 78
AUTHORS
David V. MacCollum P.E., CSP: Hazard Research and Development Rowena I. Davis: Editorial Analyst
ACKNOWLEDGEMENTS
Special thanks to the following parties for their assistance in making this study possible:
Center for the to Protect Workers’ Rights for the funding of the investigation.
Numerous discussions and insight of the participating engineers and scientists:
Jack Ainsworth, David Baker, Bob Dey, George Karady, Ben Lehman Mel Myers, Jeff Speer, John van Arsdel
For over fifty years the research of the many concerned and qualified people who have examined the syndrome of powerline contact has gone overlooked. However, their wisdom has proved to be prophetic. Neil Chitwood, chief of the safety research department of the Portland District U.S. Army Corps of Engineers (USACE) in the 1950’s, was a profound mentor of the safety engineering profession as a visionary who recognized that hazards had to be prevented. His logic was that reliance on personnel to overcome worksite hazards was nothing more than an eventual death sentence. He was among the early advocates of pre-construction safety planning to eliminate worksite hazards before the workers and equipment arrived at the worksite. Merril Ely, founder of the Portland Chapter of the American Society of Safety Engineers (ASSE) in 1940 and chief of the safety branch for the North Pacific Division, was a strong supporter of Chitwood’s doctrine. In those early years of safety engineering, Bob Jenkins, the safety director for Chief of Engineers in Washington was one who made the Army’s safety manual EM 395-1-1 a respected reference for nearly fifty years. Without these forerunners and others like them to advocate safe workplaces to preserve human life, this study would have not been written.
ABBREVIATIONS
A/E architect/engineer
ANSI American National Standards Institute
ASME American Society of Mechanical Engineers
ASSE American Society of Safety Engineers
CIMA Construction Industry Manufacturer’s Association
EMI Equipment Manufacturers Institute
ENG Electronic News Gathering
FIEI Farm Industry Equipment Institute (Currently EMI)
HIFI Hazard Information Foundation, Inc.
HRPS Hazard Reduction Precedent Sequence
MADDDC Mobile Aerial Devices & Digger Derricks Council
MESA Mine Enforcement Safety Administration
MSHA Mine Safety and Health Administration
MOTACC Manufacturers of Telescoping and Articulating Crane Council
NEC National Electric Code
NESC National Electric Safety Code
NIOSH National Institute of Occupational Safety and Health
NSC National Safety Council
OSHA Occupational Safety and Health Administration PPCP Prevention of Powerline Contact Plan
PSCA Power Crane and Shovel Association (part of CIMA)
SAE Society of Automotive Engineers
ABSTRACT
INTRODUCTION
METHOD
CASES (APPENDIX A)
TIMELINE
EXPERT REVIEW
RESULTS
CASE STUDIES STANDARDS COURT TRANSCRIPTS EXPERT ANALYSISDISCUSSION
SYSTEM SAFETY ENGINEERING ELIMINATING THE HAZARD GUARDING THE HAZARD WARNING OF THE HAZARDRECOMMENDATIONS
ORGANIZATIONAL MANAGERIAL TECHNICAL
BIBLIOGRAPHY/RESUMES (APPENDIX B)
ABSTRACT
The Hazard Information Foundation, Inc. (HIFI) has conducted an investigation to develop a timeline of historical and current data on powerline contact by cranes and other boomed equipment. The focus of this investigation is to identify the reasons why existing safety requirements are not effective by looking beyond the behavior of the victim, job site operating personnel, and the immediate employer. The study identifies the opportunities missed by the management of contributing organizations to ensure for detailed safety planning and a safe worksite before the work crew and equipment arrive for the job. It is the intention of this study to
compile hazard control data from a variety of sources to create an analysis that concludes with reasonable, enforceable safeguards and guidelines for safe crane and boomed equipment operation.
Equipment powerline contact has for more than five decades been a prominent source of worker death as well as crippling injuries and maiming. Time and evolving work practices have done nothing to reduce this hazard, and the problem of powerline contact today remains the same is it did when cranes were widely introduced in the 1950’s. This issue is so serious that in January, 2003, OSHA began to conduct meetings with other representatives from the construction industry to discuss new standards and alternate solutions to this harrowing situation (Timeline 04.01.15). At a time when the issue of boom powerline contact is so obviously important, HIFI believes that the recommendations developed by this study will help to improve the safety of the worker and the integrity of the employer and equipment.
A key issue in the study shows that the current reliance on the ten-foot “thin air”1 clearance next to, underneath, and above the powerline has proved to be a killer for more than 50 years. This current precautionary measure to avoid powerline contacts is ineffective and deters other real safety measures from being implemented. The conclusion of this work identifies over thirty alternative strategies and recommendations that have proved to prevent equipment powerline contacts; however, their implementation requires industry-wide management
1 The term “thin air” is a phrase coined by the principal author of this study. “Thin air” is a term describing the
nature of the current hazard restraint with deadly accuracy, because to date the only national regulation separating equipment booms from powerlines is a mandated minimum of ten feet of thin air, with no other visual, physical, or audible barriers.
involvement and cooperation. There exist some positive and hopeful expectations that the trend may be starting to level out due to, increasingly available technology, government safety surveillance2, and awareness that liability is the result of negligence. The ability to reduce powerline contact is within reach, if only management adopts a philosophy of voluntary acceptance and initiates measures of prevention. This study will illustrate that to achieve a safe workplace free from the hazard of equipment powerline contact, safety planning needs to start at the time of design to explicitly involve a Prevention of Powerline Contact Plan that includes specifications to be initiated by all supporting organizations and is able to be easily monitored with compliance assured by the project management.
2
Timeline 04.01.15 “ ‘Red Zones’ for Cranes Near Powerlines Discussed by OSHA Rulemaking Committee” News:
Occupational Safety and Health, Vol. 34, No.3. Boom powerline contact is a subject that has been receiving
INTRODUCTION
Cranes are used to lift and lower loads, but they vary in configuration, capacity, operation, and cost. They all use a boom to hoist the loads, and they include mobile cranes. For the purpose of this study, mobile cranes include a wide variety of boomed vehicles that can be moved under their own power. The category includes aerial lifts, pumpcrete machines, and news gathering vans.
NIOSH investigated electrocution incidents that resulted in 244 occupational fatalities during the period from November 1982 to December 1994. Based upon their analysis of these cases, NIOSH found that 18% were associated with boomed vehicle contact with an energized power line. Yenchek (2004) found that 5% of all occupational fatalities result from electrical contact, yet 14% of construction-related deaths are associated with electrical contact. Of all electrical contact incidents, one-fifth occur when high-reaching mobile equipment, such as cranes and boom trucks, contact a power line.
About 150 to 160 people are killed or maimed by power-line contact with cranes each year. These contacts occur whenever any metal part of a crane touches a bare, uninsulated, high-voltage line. Most of these contacts occur when the crane’s hoist line, boom, or other parts touch an energized power line while moving materials. Contact with electrical lines also occurs during the transport of materials with cranes in “pick and carry” operations.
Some electrocutions occur among the construction workers or rescue workers when a power line automatically re-energizes. In these incidents, the power lines re-energize at the transformer after a de-energized ground fault break was “tripped” by contact with a power line.
Objectives
Electrical power line contacts continue to occur, and OSHA is re-examining safety procedures for possible improvements. Objectives of this study are to:
1. Identify the various parties who could have exercised management authority to prevent the injury.
2. Evaluate the potential role for electric utility companies to de-energize power lines, provide temporary insulation, relocate the power lines, and lock-out automatic re-closures at the transformers to avoid re-energizing lines in the event of contact.
3. Identify opportunities for liaison between industries to delegate responsibility to ensure for minimum contact between equipment and energized powerlines.
4. Evaluate the effectiveness of the 10-foot clearance rule for operations from power lines. 5. Evaluate the distance requirements for using ground marking tape or barricades to mark the
danger zone adjacent to power lines.
6. Evaluate the actual effectiveness in the field or potential field use of alarms to warn of proximity around a power line.
7. Evaluate the use of and potential for insulated links to prevent electrical transmission in the event of power line contact as a redundant back up to protect against high voltage exposure. 8. Evaluate the actual field use of a range limiting devices for the boom as an operator aid.
Current “thin air” clearance standards have been ineffective in preventing electrical-contact injuries regarding cranes, and solutions for preventing these injuries are needed. The potential effectiveness of possible solutions—power source control, ground marking, proximity alarms, insulation links, and range limiting devices—need to be evaluated with factual information to raise the public awareness of the need for improved controls. This awareness should lead to voluntary adoption of the interventions in consensus standards, national standards, and industry regulations. Timing of this information is especially critical for use in the current OSHA negotiated rulemaking for derricks and cranes.
The investigators expect to find that every electrocution case evaluated could have been prevented by one or more of the aforementioned interventions. Moreover, the investigators expect to find that crane operators, riggers, and other crew members working in the current organizational structure cannot prevent power line contacts without specific changes in management priorities for preparing the site prior to the initiation of work.
In addition, a specific entrenched belief regarding the unreliability of insulating materials, proximity devices, and range limiting devices needs to be challenged. An example of old information that this study addresses is the criticism that has been related to monitors for proximity alarms that use magnetic sensors, which fail to sense energized power in lines that are not transferring current. New research shows that proximity alarms with electrostatic sensors are reliable in sensing voltage in energized lines, even when current is not flowing.
Research beyond this study can be expanded to other construction equipment in which power line contacts have occurred. This equipment includes aerial lifts, backhoes, excavators, pump concrete machines, and dump trucks.
Overview
The overall goal of this study is to identify the practical physical improvements and operational requirements which increase the opportunity to remove the hazard of equipment powerline contact before the personnel and equipment arrive at the worksite. It consists of five phases, which are outlined in the Method section. The Timeline was developed as an aid for the reader to enhance awareness of how historical sequences crafted current ideas and methodology regarding equipment powerline contact. It contains case examples, lists of ANSI and OSHA standards, excerpts from depositions, and articles regarding every aspect of powerline contact. It also includes studies on safety appliances, worker behavior, and effects of electrical current. HIFI has taken pains to present as much published literature as possible to provide an opportunity for the reader to see whole issue surrounding the dangers of powerline contact. By revealing multiple points of view, the timeline is able to provide context and explain why many different opinions and erroneous myths concerning the prevention of powerline contact exist. The Results section provides a broad overview of why current measures are inadequate. The Discussion outlines key points to act as the basis for a successful powerline contact avoidance plan. It also assimilates and reviews data presented in the Timeline and paves the way for the Recommendations. The Recommendations section provides a list of step by step suggestions and actions for management to undertake to significantly reduce or eliminate the hazard of powerline contact. The Observations section is a peer review by several engineers and scientists to highlight how the suggestions in the timeline will reduce human suffering while reducing costs. The three appendixes (fifty examples of powerline contacts, resumes of peer reviewers, and a list of commercially available safety appliances for the prevention of equipment powerline contact) all serve to enhance the available information on powerline contact by providing background information on all facets of the hazard of powerline contact.
Of the above-mentioned sections, the timeline is by far the more intricate. Information contained in this section is direct text or text-based, and has been put together with the purpose of illustrating how both workable and unworkable options have evolved, as well as the choices available to prevent further carnage. The timeline also reveals the myths and misinformation, which serve to obstruct, delay and discredit adoption of hazard prevention measures that could prevent equipment powerline contacts.
A crucial part of the timeline of this study incorporates a list of fifty powerline contact litigation cases. The proposal’s objective to evaluate hazard control depends upon this case file. The file not only addresses the defect that led to the injury, but it also addresses the state of the art (technology) for hazard control given the circumstances of the injury. Thus, the case addresses the cause of the injury and how the injury could have been averted.
Case Studies
Although only fifty cases are presented in Appendix A, HIFI alone is aware of an estimated 1,500 instances of litigation involving equipment powerline contact. The number of actual injuries and deaths caused by equipment powerline contact is much greater, because often they do not fall within the reporting requirements of OSHA or MSHA, as many of the victims may be self-employed and therefore exempt from the reporting requirements of the federal government and various states’ workers’ compensation boards. (Current Federal reporting does not include injuries and fatalities of public employees, self-employed workers, or employees under other jurisdiction such as transportation.) In addition, not all injuries become involved as litigation.3
The listing of fifty occurrences is intended to show the diversity of equipment and hazards that cause powerline contacts. The occurrences are listed chronologically with hazard prevention concepts that arose simultaneously. It is important to start the study of cases in the late 1960’s in order to show both knowledge of and need for various design improvements, a higher safety standard, and measures taken. The timeline is crafted to reflect this evolution and show why some design improvements were developed. Even though many cases that have been litigated date back beyond five years, they are relevant to revisions of the OSHA standard regarding cranes. Including older cases in the timeline shows the repetitious nature of occurrences and the habit of some management to neglect powerline contact prevention over a span of nearly fifty years. The investigators have observed and expect to find in this study that even with the current OSHA standards, which are dated, that they fail to protect workers from electrical contact injury. The sample to be used in this study will be drawn from the period that the current OSHA crane standards have been in effect.
3
Excerpt from the document shown as “Timeline 97.10.00”, Pg. 4: “This study has two main limitations, based on the use of OSHA data. First, the proportion of all crane-related deaths in construction which OSHA investigates is unknown and the detail available for analysis in the OSHA report summaries varies. Electronic reports were sometimes incomplete.”
The listing of incidents with older equipment is beneficial to this study for another reason: the existing inventory of older equipment continues to present an ongoing hazard as dangerous equipment that is still in use. Since the equipment is the same, (some cranes last for over fifty years) and existing safety standards have shown little improvement from the requirements of the 1960’s to the present4, the chronological link between older and present litigation becomes all the more important. Three-fifths of the 50 example cases, however, occur after 1990, illustrating the severity of the ongoing hazard as the population of crane and other boomed equipment in use has grown dramatically.
The case file is a sample listing of real-life tragedies that have taken place over the years evaluated in this study. These accounts represent a fraction of the cases on record. The cases chosen here are not intended to represent proportionate percentages of injuries or deaths from specific causes, but to include all types of equipment and scenarios. Though all these cases were chosen for specific purposes and lessons, a reader of this study must not look upon this sample pool as a microcosm of typical powerline contact instances. The following points must be taken into consideration when assessing the cases:
♦ National statistics suggest that 20-28% of the total equipment powerline contact incidents result in fatalities5. In the list presented in this study, 48% of the incidences resulted in death. This decision was made in order to show the gruesome severity of any potential powerline contact. It is also important to keep in mind that an average of 140 powerline contacts occur every year.6 The total deaths by electrocution that will occur this year exceeds the total
number of death instances presented in this study.
♦ In his book Crane Hazards and Their Prevention, (ASSE, 1993) David V. MacCollum gives the statistics that various types of cranes account for over 90% of all powerline contact instances. While this is true, the occasional occurrence of contacts such as the one involving
4
Starting in the early 1980’s some safety appliances such as anti-twoblocking devices, load measuring systems, boom angle and boom length indicators began to be provided as standard equipment by the manufacturer even though the safety standards did not reflect such as requirement.
5 Timeline 1967, “A Survey of Non-Employee Electrical Contacts” (Pamphlet), Research Committee, Utilities
Section, NSC. See also Timeline 1971, “Electrical Work Injuries in California” Division of Industrial Safety, State of California Human Relations Agency, Department of Industrial Relations
6
According to Crane Hazards and their Prevention (MacCollum, American Society of Safety Engineers) 150 to 160 people are killed or crippled each year by powerline contact. According to OSHA data from 1992-2000, approximately 19 workers are killed every year from powerline contact. If the average ratio of deaths to total accidents is 20%, approximately 100 workers are injured every year. It is important to remember that 21 states have
the dump truck (see A-23) are all the more damaging because there has been no precaution against them. All boomed and raised equipment must take precautions against powerline contact.
♦ Aerial lift contacts, while disproportionately represented in this case list, nonetheless illustrate a serious epidemic. Proper precaution and insulation for lifts is crucial because this is the equipment used to execute live line work. In lifts not used by the electric utility, the danger remains high because of the person’s proximity to powerlines and their nonexistent escape options.
♦ The listing of all the recent occurrences of injuries and deaths resulting from powerline contact with the mast of an electric news gathering (ENG) van was included to show that corporate management should not leave the delegation of ENG van design safety to the individual network station, as they do not have the expertise to establish design priorities. The assemblers of ENG vans are installers of various pre-designed communication systems, and they are too uninformed in the field of engineering safety. In each of the cases, highly disfiguring or fatal injuries occurred. There is overwhelming evidence by the injureds’ counsel on how the electrostatic proximity detector can be installed to prevent the mast from being raised when the ENG van is underneath or immediately adjacent to the overhead powerline. In all cases, the presence of an electrostatic proximity detector would have been effective in preventing the powerline contact. These cases are a clear example of where the corporate management needs to provide voluntary leadership and possible funding to ensure the safety of the TV newsgathering personnel. A relatively high proportion of cases of this type is represented in the case index to show that this type of incident is an industry- wide, recurring epidemic that must be addressed.
According to “NIOSH ALERT # 85-111: Preventing Electrocutions from Contact Between Cranes and Powerlines”, there were approximately 2,300 lost workday occupational injuries in the U.S. in 1981 which resulted from contact with electrical current by crane booms, cables, or loads, resulting in 115 fatalities and 200 total permanent disabilities. The importance of these numbers lies in the fact that one injury can cause the taxpayer thousands of dollars in social security. Though their own reporting programs and do not report to OSHA, and of those that do, many accidents are not reported or are reported incorrectly, and final figures are not standardized to any one criterion.
silencing orders from many courts prohibit an accurate monetary breakdown of lost funds, a statistical review of costs of standard implementation and safety devices would be far less than the money which burdens the economy with medical bills, litigation, lost work time, and damaged equipment.
Additional information from the case list (Appendix A) has been withheld and changed for the purposes of the study. The names of the injured have been deleted to protect their privacy. The identity of most defendants is omitted because this information detracts from the focus on the appropriate hazard prevention measures that should have been initiated. By necessity, the specific dollar amounts paid by various defendants to injured parties or their survivors are omitted from this report, as settlement agreements generally prohibit disclosure of this information. 7
In addition to the prohibition of the mention of specific dollar amounts, information on the damages awarded by verdict or settlement agreements, ranging from hundreds of thousands to several million dollars, is not a valid index of the severity of any hazardous condition and serves to develop biases that tend to compromise the voluntary acceptance of available design improvements, use of safety appliances, and management priorities of safety. This issue will be discussed further in the Results section of the study.
7
It is important to recognize that the prolific use of gag orders severely impedes the free flow of hazard information and denies the basic right of freedom of speech to the public. Gag orders suppress public knowledge and discussion of the reasons for dangerous conditions and circumstances, allowing them to persist and endangering lives in the future. Associate General Council for ATLA James Rooks, in “Confidential Settlements Under Fire in 13 States” (Lawyers Weekly USA, April 30,2001)discourages gag order by saying “The first principle is one of open courts; there is no recognized right of privacy for corporations. Confidentiality plays a reasonable role in domestic relations or juvenile cases, but beyond those no-brainers, there should be a presumption of openness. A lot of the requests for secrecy in settlements are made to all corporations to continue to hide the information that other lawyers representing clients would like to find.” He goes on to use examples like the secrecy over exploding gas tanks of Ford Pintos and defective Firestone tires, which could have saved many lives if truth about their products had come to light earlier. For more information on gag orders see the article “Strictly Confidential” (Massachusetts Lawyers Weekly, 1993, available in the Important Documents section of the Lawyers Weekly USA website.
METHOD
Phase I of this study screens some 1500 equipment powerline contacts that were in the HIFI computer data bank and select fifty occurrences, which may have met most of the following criteria:
! Cases that had been a subject of a detailed hazard analysis report.
! Cases with sufficient depositions of various defendants and other personnel who should have acted to prevent powerline contact.
! Cases that showed the greatest diversity of equipment involved in a powerline contact. ! Cases that showed the greatest number of parties who had the responsibility to ensure a
safe workplace but did not prevent the hazard of equipment powerline contact. ! Those which involved serious crippling injuries or death.
! Those of historical importance to show industry knowledge of alternate methods or use of appliances to prevent equipment powerline contact (usually revealed by litigation discovery).
! Two fifths of the cases selected occurred in a twenty-two year period between 1968 and 1990 to include significant landmark cases establishing judicial safety precedents.
! Three fifths of the cases selected occurred after 1990 to illustrate current circumstances that led to equipment powerline contacts.
Phase II of the study is the preparation of Appendix A, a detailed summary of each of the fifty cases with the pertinent information that identifies:
! Court and case number ! Date of occurrence
! Equipment and facility involved ! Hazard
! Summary of the occurrence, which briefly describes the scenario, the type of powerline, and various parties who were involved
! Disposition
! Notes that highlight the key issues
Phase III of the study is analysis process, which relies on the principles of safety engineering. In today’s world the universal use of heavy equipment presents a continual potential to come into contact with powerlines. The following tenet should become the basis for developing alternate rules of management conduct: “Any potential circumstance of equipment usage that will
cause a powerline contact is always unreasonable and always unacceptable when reasonable powerline contact prevention planning, design modification, or the use of hazard prevention devices or appliances can be used to eliminate or minimize the possibility of powerline contact.”
This is not an arbitrary tenet for management to fulfill upon the realization that a hazard is always present, for a hazard is always found in one of three modes8:
♦ Dormant: unable to cause harm ♦ Armed: able to cause harm
♦ Active: causing harm with little chance of escape
This definition has a universal application to all hazards and can be explained in terms that are pertinent to equipment powerline contact.
An overhead powerline with a well-established clearance of 18 ft or more above the ground seems not to present a hazard when a crane or other boomed or masted equipment that can reach it is not present. However, though it is unreachable, the powerline silently carries dangerous amounts of electricity. It is, however, potentially lethal. Even though there is no chance of contact under ordinary circumstances, the potential of danger that an energized powerline presents makes the hazard of powerline contact dormant.
An overhead powerline hazard becomes armed the moment a crane or other boomed or masted equipment that can reach it is brought into the immediate vicinity. The storage of materials or construction activity under the powerline arms the hazard and becomes a key factor,
8 This definition of a hazard is expressed by David MacCollum in affidavits and sworn court testimony. He
introduced it to the field in the ASSE Glossary of Safety (1991) as well as in Crane Hazards and their Prevention (ASSE, 1993). This analysis has been widely accepted by safety engineers and is often used in the process of risk-hazard analysis.
as cranes are used to easily lift the materials in the function of either locating or removing materials from under or adjacent to overhead powerlines. Even the filling of storage bins on farms has resulted in raising equipment booms into a powerline and causing electrocution9.
Once the powerline has been contacted the hazard is in the active mode, and for anyone in the ground fault path10, it is usually too late to escape injury. Powerline contact can most
effectively be prevented by not allowing the hazard to become armed in the first place. If
circumstances are such that it is impossible for crane or other equipment to be physically separated from the powerlines, available technology in the form of various devices provides alternatives that can substantially reduce the probability of actual contact by guarding with insulation or warning of impending danger with an electrostatic proximity alarm. Such devices should not be used as substitutes for a safe work location, but primarily as backup features that provide an opportunity to revise the activity in a safer manner.
Phase IV of the study is the development of a historical timeline to place in chronological order the fifty occurrences, juxtaposing them with publication standards, requirements, studies, treatises, excerpts of sworn deposition testimony, and use and development of a variety of safety devices and operational procedures. With this type of overview, both effective and ineffective hazard prevention measures are identified.
Phase V of the study presents the comments of eight field experts. These comments, entitled “Peer Reviews” provide specialty testimony and provide knowledgeable perspective to expand and clarify ideas brought up in the text of the study. These comments are in turn incorporated into the “Discussion” and “Results” section of the study.
Phase VI of the study utilizes the facts revealed in the timeline to create an evaluation of the current methods and commonly held opinions regarding the continuing occurrence of boom powerline contact. The “Discussion” section of the study pinpoints trends in legislation and accountability that must be reshaped if the hazard of powerline contact is to be successfully
9 See Appendix A7, A8
10 Ground fault is the term for the path of grounding for an electric current. Current flows in the path of least
resistance until it is grounded and the energy dissipates. Ground fault path is the route the electric energy takes to become grounded. When the path is a human body, serious electrical damage or electrocution can occur.
overcome. The “Analysis” section offers sound and logical reasoning regarding the reliability of commonly proposed safety measures and pinpoints specific situations to perform a situational analysis.
Phase VII of the study develops a listing of recommendations that would serve as effective, practical, and reasonable hazard prevention measures for management to initiate. These recommendations are primarily actions for management to eliminate or minimize the hazards before they become an issue for operating personnel.
Phase VIII provides a working copy to various professionals who provide a peer review, their own conclusions and summaries consistent with their own expertise.
TIMELINE:
TIMELINE ANALYSIS
The timeline developed for this study was compiled from primary sources and utilizes direct quotes and documented information to convey an honest account of the progress towards the adoption of safety guidelines and safety appliances. This includes articles and test accounts that advocate or prove the effectiveness and durability of such standards and appliances as well as the accounts that attempt to disprove it. The negative accounts serve to illustrate the reasons why safety appliances such as insulated links and proximity alarms are today not fully accepted by manufacturers, purveyors, rental agencies, and contractors. The text of this study may refute these accounts in order to expose weakness of argument or logic, thus strengthening the case for adoption of these safe measures and appliances. The primary purpose of the timeline is to provide a concrete basis for the analysis that leads to the Recommendations. Notes inside the timeline are written in purple, and are interjections of the authors of this study for the purpose of clarification and as summarized in the Discussion.
Though a bibliography is present in the study, many citations and footnotes in the text will be cited directly from the timeline and will contain the date of the quote or article the way it is presented in the timeline for easy referral. Any additional citations appear in Appendix B in the Bibliography.
Color Guide
♦ Red- Examples of litigation cases of 50 real-life powerline contacts, chronologically interjected in order to illustrate the technological advancements and popular beliefs available at the time of the incident.
♦ Blue- Any standard that can be considered an enforceable mode of regulation; ANSI and ASCI are portrayed in blue, as well as National Safety Council (NSC) standards and military-issued regulations pertaining to at least one organized group.
♦ Green- Excerpts from court transcripts and recorded depositions. In providing the court and case number the study is able to grant access into further research without biasing the reader by listing plaintiffs or defendants. The authors of this study have attempted to provide context enough to make the excerpts understandable while releasing the reader from irrelevant reading. Full transcripts of all depositions used will be provided upon request.
♦ Purple- Notes that have been interjected into the text boxes by the authors of this study for the purpose of comment or clarification.
A TIMELINE HISTORY OF POWERLINE CONTACT
1951 Accident Prevention Manual for Industrial Operations, 2nd Edition: National Safety Council (NSC); 12-16:
“Commercial warning devices are available which work by induction from a powerline, ringing a warning bell in the cab when the boom or cable approaches too close.”
Note: This is the first published mention of available safety devices that warn of impending crane powerline contact.
52.10.28 August Albrecht invented a detector for Electrical Powerline for Vehicles with Extended Booms, Patent # 2,615,969
1953 “Power Line Accidents Kill Men, Ruin Equipment, and Delay the Job” National Safety Council Memo reminds workers the proper precautions and steps to avoid powerline contacts.
1954 Data Sheet # 287, Published by the National Safety Council (NSC), 444 N. Michigan Ave, Chicago, IL
Pg. 2, P.5: “Various alarm devices have been developed to warn the operator when the boom approaches too closely to the powerlines.”
1955 Accident Prevention Manual for Industrial Operations, 3rd Edition, NSC; 14-12: OVERHEAD POWER LINES
“Overhead powerlines within the plant area create an electrocution hazard to workmen when cranes, shovels, and draglines in the vicinity of excavation and other construction work. An electronic safety device for warning crane operators of proximity to powerlines should be installed on the construction crane equipment to be used.”
“Such a device will warn crane operators and workmen of proximity to powerlines from a distance of 8 inches up to 400 feet from the lines, depending on the voltage in the lines and the setting of the sensitivity control by the operator. It functions on AC or DC voltages, lines, and shows shallow-buried underground cables.”
“The device uses special circuits so that it does not depend upon the current being drawn through the lines to set off the alarm. The presence of voltage is all that is necessary to cause the device to function at a safe distance. To set the device, the boom is swung within the desired safe distance from the transmission lines, and the control is advanced until the horn sounds. The horn will sound again at any time the boom enters this pre-set danger zone.”
19-22: “Electronic devices are available which can be attached to the boom and which will sound an alarm if the boom comes within a predetermined distance from a live wire.”
1955 The incident of walking a latticework crane boom into a powerline powering a concrete batch plant, causing a loss of power when mixing quick-set concrete, resulted in the requirement to dismantle and replace the two mixers that had become frozen with cured concrete. No injuries were involved, but the incident prompted the Portland District Army Corps of Engineers to initiate special conditions for three dams that would be under construction. The essence of the changes required the following: All powerlines in the work area will be 90 feet above the ground and all crane booms will be less than 80 feet long. During the next ten years during the entire construction cycle no powerline contacts occurred.
See item 58.08.00, where this provision would be in the Contractor’s accident prevention plan.
56.01.10 James E. Auld invented the Automatic Control System for Hoisting Apparatus, Patent # 2,730,245
1957 Data Sheet # 448, NSC:
Insulated Hook; An electronic safety device for warning crane operators of proximity to powerlines is commercially available. Also commercially available are insulated load-line hooks and insulated crane boom guard.” This reference contains
illustrations of these devices.
57.04.16 Daniel R. Winters invents an “Automatic Approach Alarm”, Patent # 2,789,282 58.08.00 Safety Policy and Procedure Manual, North Pacific Division, US Army Corps of
Engineers, Portland, OR
Pg. 18: Part IV- Accident Prevention On Contract Work:
“The accident prevention provisions are as much a part of the contract as any other provision set forth in the contract for the control of the work.”
Section II: Planning 1. Contractor’s Accident Prevention Plan: “To insure
cooperation, coordination, and complete understanding in the application of accident prevention to contract work, District Engineers will address a letter to each contractor immediately following the making of a contract award. This letter will include a brief outline of the objectives of the Corps of Engineers in accident prevention and will stress the importance of the contractual safety obligations of the contract. It should invite attention to the contractual requirement that a written accident prevention plan will be carefully reviewed by both operating and safety engineering personnel. Paragraph 2009.11 O&R, EM 385-1-25. Following this review and prior to the initiation of work, the contractor will be requested to meet in conference with appropriate construction personnel to discuss his accident prevention plan and the inherent and specific hazards of his contemplated operations. The understandings reached at this conference will be tabulated in writing. One copy will be furnished the contractor and one copy will be filed in the official contract file.”
Note: This regulation was the first of its kind, and was soon found as a regulation in general safety handbooks throughout the Corps of Engineers. It was the advent of designating responsibility and authority to one overseer. The requirement for the contractor’s accident prevention plan soon became the keystone of the Army Corps of Engineers’ safety program. Variations of this regulation are repeated throughout the timeline, as it has evolved into a key safety requirement.
58.10.00 Sheppard, Paul E. “Crane Contacts can Kill”, National Safety News, NSC: Pg. 130: states “musts” are: crane boom protector, an insulated safety hook, and a powerline proximity warning device.
1959 Accident Prevention Manual for Industrial Operations, 4th Edition, NSC; 19-2: “Electronic devices are available which can be attached to the boom and which will sound an alarm if the boom comes within predetermined distance from a live wire.” “Boom guards of wood or of pipe mounted on 15-kv insulators provide mechanical protection against contact.”
“If a crane boom comes into contact with a conductor, the hazard is greatest to the hooker of others who may touch the load or the sling. To protect against this hazard a load hook with an insulated link, now commercially available, can be used.”
59.07.28 C.B. Ingram invents the Insulated Link, Patent # 2,897,257
59.09.00 Elkins, Sam S. “Crane Booms v. Powerlines”, National Safety News, NSC: Pg. 121 lists several types of electronic warning devices, crane boom guards, and insulated hooks.
1960’s The military transition of handling bulk supplies included the use of cranes. Until older WWI and WWII supply depots could bury or relocate powerlines, they had considerable success in preventing powerline contacts with boom cages, insulated links, and proximity alarms. These experiences prompted many of the following military orders for the use of safety appliances.
See 62.03.00, 64.02.00, 64.02.04, 65.10.01, 66.10.01, 67.01.00, 69.07.28, 69.10.01, 70.04.20, 73.12.00, 74.01.00
1960 “Survey of Contacts with Overhead and Underground Electrical Lines (out of 95 replies received): 1958 National Safety Council Newsletter # 112.03-07030
60.02.09 F.E. Barnes invents the Insulated Tension Link and Method of Making Same, Patent # 2,924,643
60.03.15 William C. Burnham invents the Electrically Insulated Link, # 2,928,893
60.08.23 Arthur J. Thomas invents the Crane Boom Guard Attachment, Patent # 2,950,016 61.06.20 Arthur J. Thomas invents another Crane Boom Guard Attachment, Patent # 2,989,194 62.03.00 U.S. Department of the Air Force, Dept of Defense, T.O. 36C-1-4: Electroduction
Protective Devices for Cranes and Shovels: Requires the use of di-electric boom shield and insulated link for all cranes dispatched for use in the vicinity of high-voltage powerlines.
63.08.00 Construction Safety Standards, Bureau of Reclamation, U.S. Department of the Interior; P 9.1.11C:
“An automatic warning device has been installed on the equipment and used together with the utilization of a signalman to warn the operator when the equipment
approaches the 10-foot clearance.”
1964 Accident Prevention Manual for Industrial Operations, 5th Edition, NSC: 18-24: “Electronic Devices are available that can be attached to the boom and will sound an alarm if the boom comes within a predetermined distance from a live wire.”
“Boom guards of wood or of pipe mounted on 15-kv insulators provide mechanical protection against contact.
If a crane boom contacts a conductor, the hazard is greatest to the hook-on man and others who may touch the load or the sling. To protect these men, a commercially available load hook with an insulated link can be used.”
1964 W.E. Rossnagel, (Consulting Safety and Fire Protection Engineer) Handbook of Rigging for Construction & Industrial Operations,” 3rd Edition
Pg. 228: “There are on the market several types of electronic devices intended to be mounted on the top of the boom. Such devices will sound an alarm or stall an engine if brought within a pre-determined distance from an energized electrical conductor.” 64.02.00 Department of the Army, Cir, 385-1 Safety: Provide a di-electric boom shield and
insulated link in lifting line above the hook.
64.03.17 Daniel R. Winters invents the Proximity Alarm, Patent # 3,125,751
64.02.04 Cir 385-1 “Use of Cranes, Crane Shovels, Draglines, and Similar Equipment Near Electric Powerlines” Headquarters, Department of the Army
“3 a. The most feasible means of reducing the probability of electrocutions and injuries as a result of crane booms and their loads contacting energized powerlines is to equip the crane booms with dielectric shields and to install insulated swivel links in lifting above the hooks.
4. Commanders will analyze Army crane operations, accident experience, and the electrocution potential of the equipment involved and will apply such of the following safeguards as are required to insure safe operations:
a. Provide a dielectric boom shield and an insulated link in the lifting line above the hook.
b. De-energize powerlines whenever equipment is working close to the lines. c. Notify the operating utility when cranes are to be used in close proximity to
energized powerlines.
d. Ground the frames of cranes operating in close proximity to energized powerlines.”
65.02.02 H.W. Volberg invents another Proximity Alarm, Patent # 3,168,729
65.10.01 “Memorandum for Record” Directories of Research , Development, and Engineering, U.S. Army Military Equipment Command, Fort Belvoir, Virginia
Discusses Ely Mechanical Boom Swing Limiting Devices and SigAlarm™: “[Range Limiting Devices] provides a positive stop when the stop blocks are set and does not interfere with operation when the stop blocks are removed from the ring.”
“SigAlarm™- If properly set, this unit can provide warning upon approach to a powerline.”
66.10.25 T.O. 36C-1-4: “Electrocution Protective Devices for Cranes and Crane Shovels” Published under the authority of the Secretary of the Air Force
2 a. “A dielectric boom shield and insulated link in the lifting line at the hook will provide approximately 90% protection to personnel working with the equipment in close proximity to high tension electric wires.”
3 c. "Only cranes and crane shovels equipped with the protective device will be dispatched to operate in the vicinity of high tension lines.”
1967 A Safety Handbook for Mobile Cranes, The Royal Society for the Prevention of
Accidents and Institute of Material Handling (Most respected and prestigious safety group in Great Britain)
“There are available on the market, proprietary devices designed to give a warning when the crane jib comes within a predetermined distance of the power cables. These devices are attached to the head of the jib and in one case, the device actually cuts off the crane power and prevents its further movement.”
67.01.00 Department of the Army, TB-385-101 Safety: Instructions to equip crane booms with di-electric shields and links.
67.01.03 A. Stenger, Jr., et al receive a patent for the invention of “Voltage Responsive Devices and Methods of Voltage Detection”, first filed on June 24, 1963; Patent # 3,296,494
67.03.00 EM-385-1-1, General Safety Requirements, Corps of Engineers, Department of the Army, P 15.E.09: “Anytime it is necessary to operate a boom-type equipment where there is a capability of encroachment on specified clearances, the boom shall be equipped with an insulated cage guard and an insulating link shall be installed on the load line.”
1968 USAS B30.5, Safety Code for Crawler, Locomotive, and Truck Cranes, American Society of Mechanical Engineers, (American National Standards, now known as ANSI)
5.3.4.5b: “Cage-type boom guards, insulating links, or proximity warning devices may be used on cranes.”
68.04.04 A latticework crane boom was pointed directly underneath a live 7,200 V powerline that the electric utility lineman failed to disconnect. A worker lost his right arm and sustained other mutilations when he released the lifting hook from a 60” culvert, causing the boom to raise three feet into a powerline. An insulated link could have prevented injury. See Appendix A-1
This case was among the start of a trend that addressed a third party’s duty and ability to ensure for a safe workplace by de-energizing a powerline to prevent a crane boom contact when placing culvert pipe under a powerline.
68.05.20 “Contacting Overhead Electrical Powerlines”—Mobile Cranes Technical Bulletin #1 (Study by Liberty Mutual)
Discussed Proximity indicators, boom enclosures, and insulated links as safety devices.
1969 Accident Prevention Manual for Industrial Operations, 6th Edition, NSC:
Pg. 430: “Another device that reduces the hazards involved in crane contacts with electric lines is a cage-like insulating guard that can be attached to the top side of the boom. Also available is an insulated safety link that can be installed between the load hook and load attachment cables, or the line hook and sling, to provide protection to the hookup men.”
Pg. 560: “Electric devices are available that can be attached to the boom and will sound an alarm if the boom comes within a predetermined distance from a live wire. This equipment is subject to failure and should be used only when it is absolutely impossible to maintain minimum clearances, barricade, or de-energize powerlines.” “Boom guards of wood or of pipe mounted on 15-kv insulators provide mechanical protection against contact.
“If a crane boom contacts a conductor, the hazard is greatest to the hook-on man and others who may touch the load or the sling. To protect these men, a commercially available load-hook with an insulated link can be used.”
Pg. 1566: “When a mobile crane must be operated near electric powerline, the power company should be consulted to determine whether the line can be de-energized. Many fatalities have resulted from contact with powerlines, and often the power companies’ service is seriously disrupted. Various states have enacted legislation distances which booms and cables must be kept from powerlines. A minimum of ten feet is often specified; however, the recommendations of the power company and the legal requirements of the state should be observed.”
Pg. 1567: “No load may be lifted or moved without a signal. Where the entire movement of the load cannot be seen by the operator, as in lowering a load into a pit, a signalman should be posted to guide him.”
1969 “Electrical Work Injuries in California” Division of Industrial Safety, State of California Human Relations Agency, Department of Industrial Relations
This table reports the total number of accidents involving contact with overhead high-voltage lines through equipment from 1960-1969 at 572 in the state of California, with 160 of them fatal. However, we can extrapolate from disclaimers on other studies that this number represents the bare minimum of occurrences.
1969 “A Survey of Non-Employee Electrical Contacts” (Pamphlet), Research Committee, Utilities Section, NSC
Detailed Statistics: Fatal- Crane/Boom = 185, Well Drilling Rig = 25, Other Equipment =186, Total =396 Fatalities; Non-fatal- Crane/Boom 826, Well Drilling Rig = 110, Other Equipment = 593
Fatalities occurred in about 20% of all occurrences. Fatalities: 396, Non-fatal: 1529, Total: 1925
69.07.28 Directorate of Research, Development, and Engineering, U.S. Army Mobility Equipment Command, Fort Belvoir, VA
Investigation of Dielectric Boom Shields , Hook Insulator Proximity Alarms, Grounding Shields, et al.
69.10.01 SMEPB-RDE-KM “Directorate of Research, Development and Engineering: U.S. Army Mobility Equipment Command, Fort Belvoir, VA”
5 b. SigAlarm™: “If properly set, this unit can provide warning upon approach to a powerline. The reliability of the system depends upon the electrical circuits, since there are no mechanical parts. The test circuit provides a quick check of the system integrity. The exterior howler alarm might prove difficult to hear in a construction area, however, it was audible to all personnel in the test area, with the crane engine running.”
1970 Though the city highway moving permit required the involvement of the electric utility companies while towing a house through city streets with a trailer, no electric company personnel appeared at the appointed time, and one of the men moving the house was electrocuted when he attempted to use a stick to improve clearance for the house. See A-2
This case illustrates the diversity of opportunities that involve powerline contact and the need for communication and follow-up between contractors and the third party participant. Cooperation is necessary to ensure for a safe workplace.
1970 Hauf, R., “Requirements For Grounding Practices and Standards- The Revision of Report 479”
This is a detailed study that examines duration and intensity of electrical shock to determine the effects of both factors on the human body. Though many factors, such as where the shock occurred on the body and condition of the skin, yielded differing results, the report states that frequencies as low as 50/60 Hz are enough to cause fibrillation in some cases.
70.04.20 AMSME-Z: Dielectric Safety Shielding for Military Cranes and Booms, Commanding General, U.S. Army Material Command:
“The primary conclusion drawn from the investigation of crane electrocution accidents was that no “add-on” safety device can replace or minimize the need for proper action by crane operators, linemen, and supervisors.”
Note: This observation fails to include the experience of AMC in the 1950’s when updating their supply Depots, which required manual handling of their military supplies, to using cranes. At the time these warehousing streets were covered in powerlines as thick as cobwebs, which seriously impeded he use of cranes. Until such time that powerlines could be relocated or buried, AMC successfully avoided crane powerline contact injuries with boom cages and insulated links.
70.05.27 Research Laboratories: Ottawa, Canada, Division of Radio and Electrical Engineering:
“Tests on Crane-Truck Mounted High Voltage Protection Devices”
(I) Miller 25 Ton Swivel Insulator Link & (II) Electrowarn overhead powerline detector.
Results: (I) “Water was poured over the link so as to wet the surface as much as possible and the test was repeated. Corona was observed on some of the water drops but no breakdown occurred.
(II) “The warning device functions as described in the literature but its usefulness is limited by the fact that it only detects the proximity of a powerline to one point of the crane.”
Note: This report overlooks the fact that the insulated links are a redundant back-up safety device and the proximity alarm was developed just to warn of the presence of a powerline and was not designed to be a measuring device to identify the clearance from a powerline.
70.07.20 One worker was killed, one injured and one permanently disfigured with the loss of three limbs when their truck mounted crane struck a mid-span, 35,000 V powerline while guiding a pipe over an eight foot cyclone fence. Both the property owner and the electric utility company had keys to unlock the gate to the property, but did not communicate well enough with the construction crew. See A-3
In this case Robert Jenkins, retired chief of safety for the U.S. Army Corps of Engineers, related his experience of extending the 6ft thin air clearance to 10ft, a change that did not reduce injuries from crane powerline contacts. He further testified that the use of both links and a boom cage did reduce injuries from crane powerline contact by approximately 90 percent. See trial testimony of 1972.
1971 “Electrical Work Injuries in California” Division of Industrial Safety, State of California Human Relations Agency, Department of Industrial Relations
This table reports the total number of accidents involving contact with overhead high-voltage lines through equipment from 1962-1971 at 594 in the state of California, with 150 of them fatal. It appears that approximately 25% of powerline contacts are fatal.
71.03.16 August C. Clark, Charles Christianson, Julius Kaminetsky, Edward P. Duffy invent another Insulated Connector and Method, Patent # 3,571,492
71.02.00 Proposed Safety and Health Regulations for Construction, Bureau of Labor Standards, U.S. Department of Labor, Construction Safety Act, Subpart N: Cranes, Derricks, Hoists, Elevators, and Conveyors, 1518.550, (v):
“Cage-type boom guards, insulating links, or proximity warning devices may be used on cranes, but the use of such devices shall not alter the requirements of any other regulation of this pare even if such device is required by law of regulation.” 71.05.00 Occupational Safety and Health Standards; National Consensus Standards and
Established Federal Standards, U.S. Department of Labor, Occupational Safety and Health Act, 1910.180 (j) (2):
“Boom Guards. Cage-type boom guards, insulating links, or proximity warning devices may be used on cranes, but the use of such devices shall not operate to alter the requirements of sub-paragraph (1) of this paragraph.”
1972 Court Transcript of Theodore M. Leigh (Circuit Court of Cook County, Illinois: see Appendix A-3)
Cross-examination by Mr. Ozmon, Pg. 354, Ln. 1649:
“My name is Theodore M. Leigh and I live in Cedar Rapids, Iowa. I have been an employee of Link Belt a total of 29 years and presently am the manager of Product Safety. I am both an electrical and mechanical engineer and was previously the Assistant Chief Engineer. Research and development is not in my department but is in the engineering department. As a staff member, I have direct communication with that department. I am the Link-Belt man who makes recommendations on safety programs and fall within my particular job on behalf of Link Belt. I have been aware for over 20 years of a problem relative to crane boom contacts with electrical transmission lines, which often result in injury and death. I am aware that the cranes Link-Belt manufactures are to be used on some occasions in an area where there are overhead energized electrical lines.
I’ve also been aware at least 10-20 years, in my position at Link-Belt, of devices developed in relation to this problem. The three major types of such devices are: A form of cage which had dielectric properties for use on the upper end of the crane boom; a link, and a proximity device. I have never on behalf of Link Belt obtained one of the cage-type de ices for testing and examining it myself. In the various positions I have held at Link-Belt, I have never obtained and brought there for testing and examination any of the types of devices known as a link or a proximity device. I have never personally seen a cage-type device, a boom or crane guard, nor a link, nor a proximity device. I have never requested or caused any other type of testing organization to test any boom guard, link, or proximity type device. When such testing is indicated, its initiation by either Link-Belt or an outside organization would fall within my province as Manager of Product Safety. It would not be a fair
statement at all to say that my research on behalf of Link-Belt into the problem of crane boom contact with energized lines has been limited to the accumulation of literature of the various manufacturers into a Link-Belt file. You would have to go much farther than adding ‘and possibly the looking into some of the specifications of some of the items’, before I would agree to that statement.”
Court transcript of Robert Jenkins; Recross examination by Mr. Davidson, Pg. 357, Ln 3382
“I sent this letter out on the date it bears, March 10, 1971, with copies to Mr. Strnad, the president of the company, Theodore Leigh, Cozad and many others in the usual course of company business. I expressed the view at that time there was a need for warning the operators against electrical hazards. I stated that not putting on these warnings would only increase the possibility of additional accidents that might be avoided if due warning were given.”
Cross-examination by Mr. Ozmon, Pg. 368, Ln. 1732: “Plaintiff’s exhibit 91 for Identification has the appearance of a dielectric link. This is the type of item I initiated testing on within the Corps of Engineers when I became aware of it in the 2950’s. Those would be for tests of the manufacturer’s claims of the dielectric ability of the particular substance which they were made of. There were also tests of its strength since it was going to be in the load line.”
Ln 1740: Mr. Ozmon: “Mr. Jenkins, as we recessed I was about to ask you to
consider your background and your experience, your knowledge as a safety man for a good number of years in relationship to some facts I would like to have you assume, and if you will just listen to these facts for a few moments and then I will ask you a question based on those facts. I would like to have you assume back in the year of 1970, assume a crane in operation, a crane with a thirty-foot boom. Assume on a particular morning in July that this crane was being operated in close proximity to an overhead
continued energized 34.5 kV line. Assume that in this operation that there was required by this crane the picking up of certain metal, steel pipes, and that these pipes were being lifted by means of a metal choker with hooks that went into the ends of each pipe and then the choker lines back to the hook at the end of the load line. Assume that there were three men on the ground holding this load, one man at the end of the metal pipe and two men at the other end of the metal pipe all with their hands on the load guiding and directing as movement was being made by the operator, that in the course of this movement the boom swung and the boom either came in contact with the 34.5 energized line or it came close enough that there was an arcing, and assume the contact point is-looking at Plaintiff’s exhibit #24- here, here and here on this item at the very head of the boom. Assume that is the contact point. Assume by this contact that there was transmission of current down the load line into the bodies of these three men handling the load. Now, assume one other fact. Assume as in Plaintiff’s Exhibit 86 that there had been within the design of that crane a boom cage or boom guard similar to that which appears within this Plaintiff’s exhibit 86, and assume that that cage had been in good operating order, and assume that it had good operating dielectric insulators. Do you have an opinion as a safety man in relationship to the construction industry as to whether the presence of that boom cage within the design of the crane would or would not have prevented the transmission of the current I referred to down the load line and into the bodies of the three men?
A: “Yes, sir, I do.
Q: What is your opinion relative to that? A: “It would have prevented it.”
Q: “I would like to have you assume those same facts again up to the point as to when I asked you to assume the presence of a boom cage in the design of the crane.
Assume all the same facts and assume the contact, assume the transmission down the load line and into the bodies of the men. Now assume that there was present within the design of that crane a dielectric safety link within the load line, assume that if you will. Do you have an opinion as to whether the presence of the dielectric safety link within the design of the crane would or would not have prevented the transmission of the electric current down the load line and into the bodies of the three men?
A: Yes, sir, I do.
Q: What is your opinion on that, Mr. Jenkins?
A: It would have prevented it. There are four major categories if safety devices in relation to this electric contact problem: the boom cage type, the safety link, the alarm type and the line hose. Electro Alarm and SigAlarm are the two major manufacturers of the alarm type. The link and cage are designed to prevent transmission of electrical current if there is a contact. The alarm is a warning type of system rather than prevention. I am acquainted with the alarm of proximity type device. As Director of Safety for the Corps of Engineers of the U.S. Army, I have initiated tests of the manufacturers’ claims regarding this device.
Pg. 379, Ln 1781
“The proximity device requires a setting. This gets it into the area of human error which I was talking about. The Corps of Engineers require the device I was talking about only when working in the vicinity of overhead energized wires. Whenever possible, one of the requirements was to de-energize the powerlines and another was to notify the operating utility when cranes are to be so used. When working with the contractors, we have the preliminary conference advising them to get in touch with the power company. One of the insulating links rates up to 50,000 V. Fifty or sixty thousand is the highest. There are many power transmission lines in the country that will exceed that. You can’t tell by looking at a line whether it has that much voltage or not. If a man is operating a crane in the vicinity of a high powerline instead of being 34 or 50 is 100,000 or 200,000 volts, the insulating line doesn’t provide protection for the men holding the load. It only provides protection for the capacity it
Continued is designed for and would arc right over it. If a man working in the area of a high power line with an insulated on there has got a long boom, if the line itself above the link hits the wire, the wire is energized. The link takes care of what is below assuming it is below those voltage limits. For the boom guard, the little cage, to protect the underside of the boom, you have to get an underside section. Normally, it’s on the top if you want protection. If you have a long boom and are working up there, you might hit it with the end or you might hit it underneath. Then everything is energized if you don’t have the guard underneath.
Pg. 380, Ln 1786: “If you have an insulated link and the tip of the boom hits a powerline- let’s assume it’s a high power line under 50,000 V because we know if it’s up to 100,000 it will flip over anyway- and the men are holding a long load that is swinging around and touches the crane, the crane is metal of course and the load will become energized. The safety link isn’t provided for that purpose. You can get a contact by touching the crane or if you energize the load through any means. Recognizing that the crane operator has to operate it and do other things, the signalman’s function in the vicinity of high power lines is to watch that the crane doesn’t get that close. There are usually two signalmen on a job. One signals the operator from the point of operation. He stands where he can observe the men handling the load, or he may be handling it himself, but he is the one who tells the operator when to lift and so forth. The other signalman is the watcher whose job and what he is paid for is to see they don’t get too close to the wires. The Corps of Engineers could not justifiably see requiring a contractor to pay for something where you could get better protection not involving human factors for a couple of month’s wages. A couple of month’s wages would protect the crane for the next eight years. If the work is for a couple of days, it wouldn’t be worth his time to stand there and guide these men. It was partial protection. We have found there is a great reliability factor. This is a man out there in a very boring situation with nothing else to do, looking up all the time with clouds going over, they get so dizzy they are incapable of doing it. When the crane isn’t moving, he goes under a tree and sits in the shade and doesn’t do his job. The foreman on the job is another thing.
Cross Examination by Mr. Peterson Pg. 381, Ln 1790
“It’s very difficult for either a crane operator or a signalman to see the precise relationship between the end of the boom and an energized overhead wire. That is one of the reasons I said an operator or a signalman is not as reliable as a sole means of protection. I didn’t say earlier that the ANSI standards were inadequate. I would consider any standard that relied solely on the operator or the signalman inadequate based in my experience. I observed many times that power companies patrol their lines when cranes are in close proximity and have taken this action whether notified or not because electricity can kill so quickly.”
1972 “Electrical Work Injuries in California” Division of Industrial Safety, State of California Human Relations Agency, Department of Industrial Relations
This table reports the total number of accidents involving contact with overhead high-voltage lines through equipment from 1963-1972 at 587 in the state of California, with 141 of them fatal.
Note: Again it appears that 24% of powerline contacts are fatal.
