Do not use cage-type boom guards, insulating links, or proximity warning devices as a substitute for de-energizing and grounding lines or maintaining safe clearance [29 CFR 1926.550(a)(15)(v)].
Follow ANSI Guidelines
Train workers to follow ANSI guidelines for operating cranes near overhead power lines (ANSI Standard B30.5-1994, 5-3.4.5). These guidelines recommend posting signs at the operator's station and on the outside of the crane warning that electrocution may occur if workers do not maintain safe minimum clearance that equals or exceeds OSHA requirements as follows:
Power line voltage----------------Minimum safe
phase to phase (kV)---------------clearance (feet)
50 or below-----------------------------10
Above 50 to 200------------------------15
Above 200 to 350-----------------------20
Above 350 to 500-----------------------25
Above 500 to 750-----------------------35
Above 750 to 1,000--------------------45
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 (incl. 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 machincery 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. Therefore, NIOSH recommends that not 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 (see current standards in this Alert).
All employers and workers should be trained in cardiopulmonary resuscitation.
Call for Help
Ensure that workers are provided with a quick means of summoning assistance when an emergency occurs.
The following is a sheet that you can provide to your employees.
Preventing Electrocutions of Crane Operators and Crew Members Working Near Overhead Power Lines
WARNING!
Crane operators and crew members may be electrocuted when they work near overhead power lines. |
Take the following steps to protect yourself from electrocution when operating or working around cranes that are near overhead power lines:
1. Operate cranes only if you have been trained in safe operating procedures and the Occupational Safety and Health Administration (OSHA) safety requirements.
2. Participate in all crane safety programs offered by your employer or labor organization.
3. Know the location and voltage of all overhead power lines at the jobsite before operating or working with any crane.
4. Assume that all power lines are energized and maintain the minimum clearance required by OSHA at all times:
At least 10 feet for lines rated 50 kilovolts or below
At least 10 feet plus 0.4 inch for each kilovolt above 50 kilovolts (or maintain twice the length of the line insulator, but never less than 10 feet)
5. For more protection, maintain the greater clearances recommended by the American National Standards Institute (ANSI):
Power line voltage----------------Minimum safe
phase to phase (kV)---------------clearance (feet)
50 or below-----------------------------10
Above 50 to 200------------------------15
Above 200 to 350-----------------------20
Above 350 to 500-----------------------25
Above 500 to 750-----------------------35
Above 750 to 1,000--------------------45
6. Where it is difficult for the crane operator to see the power lines or pay attention to maintaining required clearance during crane movement or operation, designate a person whose sole responsibility is to observe the clearance and to give immediate warning when the crane approaches the limits of safe clearance.
7. Be aware of the limitations of boom guards, insulated lines, ground rods, nonconductive links, and proximity warning devices. Do no use these devices as a substitute for de-energizing and grounding lines or maintaining safe clearance.
