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

NTOF Data

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.

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.

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