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.”
63.08.13 Stuart A. Coffey invents the Crane Boom Life Guard, Patent # 3,100,575
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.”
66.07.12 H.J. Hirtzer invents the Insulated Connector and Method, Patent # 3,260,796
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,
70.04.20 AMSME-Z: Dielectric Safety Shielding for Military Cranes and Booms,