This short presentation describes a preventable workplace incident where two workers in Washington state was killed on the job and is narrated by the L & I safety inspector who conducted the investigation. To view the narration script, click on the button on the lower right corner of the screen. To move between slides, or view a particular slide again, click on the same lower right hand corner button and then click on the back and forward arrows at the bottom of the screen.
Hello, my name is Brad Solheim, and I work at the Department of Labor & Industries Division of Occupational Safety & Health. I was the inspector on the day of a fatality when two workers died from exposure to a high voltage electrocution. One worker was 40 years old, the other was only 25.
On the day of the incident, the two men were working in a propane tank storage yard taking inventory using a boom truck to lift the large propane tanks. It usually takes about 5-6 minutes to lift, move and record the tank number, then reset the tank on top of the lower one. That was their job this afternoon, but there were overhead power lines located next to the tank yard.
When the crane was fully extended, the right side of the boom tip contacted the energized 7200 volt power line and the electricity ran down the boom of the crane then went to ground through the outriggers. Apparently the operator stepped off the truck platform while touching the crane causing the electrical current to travel through his body, fatally electrocuting him. Following the investigation it is probable the rigger moved into the path of the current and was then electrocuted himself. He was also pronounced deceased on arrival.
It is sometimes assumed that overhead power lines are insulated which is NOT true. They often have covering for weather protection, however this does not protect from electric shock should contact be made with a crane or boom.
Contrary to what some people believe, all overhead power lines carry enough electricity to kill. The two workers who lost their lives had not been specifically trained on the hazards of operating a boom truck near powerlines. In addition, the property owner where the powerlines were located had not been contacted by the company notifying them that a boom truck would be operating that day near the power lines. If a crane contacts a power line: Stay clear of any vehicle or equipment that has made contact Stay away until rescue workers assure you the power is off and do not attempt to rescue any persons Call 911 and the electric company immediately Warn others away
Itís important to know if equipment hits a line, nearby workers standing on the ground are in the greatest danger. †
One fact that many are not aware of is when a crane or boom truck makes contact with a power line, electrical current can flow through the vehicle and outward in the surrounding ground soil in a ripple-like pattern as illustrated in this slide.
Regulations require mobile equipment have at least a 10 foot clearance from active powerlines and often more distance depending upon the volts exceeding 50 kv.
Overhead lines can be difficult for crane and boom operators to see. One option is to select a spotter who is in constant communication with the operator. Spotter must be equipped with a visual aid to assist in identifying the minimum clearance distance. Aids may consist of providing a visible line that is painted on the ground; stanchions could be set up; landmarks showing the line-of-sight such as fence posts equipped with flags or high-visibility markings. Communication is done by hand signals, radio, telephone, or other electronic transmitting devices.
Devices, such as proximity warning systems, are often used to warn the operator to stop movement and prevent encroachment.
If you are an operator of a crane or boom that makes contact with powerlines, the safest thing for you to do is remain in the vehicle until the powerlines are de-energized. If you MUST get off the equipment due to fire or other danger, jump clear, and do not touch the equipment and ground at the same time. Land with your feet together and shuffle away keeping your feet on the ground.
Listed are some key steps to remember if management cannot de-energize the power lines: Step 1 Determine the voltage and minimum approach distance Step 2 Meet with the crew and review the process so everyone understands Step 3 Designate a spotter and provide that person the visual and audio aids to communicate with operator. Step 4 Be sure safety signs are visible to operator and workers on crane and at worksite. Step 5 Review manufacturer's operations manual for specific instructions for working around high voltage powerlines. In this tragedy these steps were NOT taken and two workers lost their lives.
Thank you for joining us today to share this case with you. Working around high voltage power lines is always a hazard, so please work safe. We appreciate your help in Keeping Washington Safe and Working.