Electrical Hazards Awareness
One of the best characteristics about a tree care professional is how they get excited to talk about and work on trees. Unfortunately, many times that excitement and desire to do tree work brings arborists in close proximity to electrical wires.
Make no mistake, electricity is a serious and widespread hazard to arborists every day. Even a simple telephone line can be energized with enough voltage to kill. Because of our exposure to electrical hazards, ANSI Z133 states that “The employer shall train each employee….” on the topic. (4.1.2 – 4.1.4(f)).
Training your team on the following tips is a great start to preventing electrical accidents within your company. However, we strongly recommend that you engage in a full electrical hazard training with every member of your field team at least once per year.
Job Hazard Analysis (JHA) and Job Briefing – Properly setting up and inspecting the jobsite and surrounding area is the first step in preventing an electrical accident. Formally, this is done when performing a Job Hazard Analysis and again during the Job Briefing before work begins. When you arrive at the job site, be sure everyone on your team checks for electrical wires and guy wires. If it is after a storm, look for electrical lines mixed up with a fallen tree or lines down on the property. When planning and performing your work, you must follow the Minimum Approach Distance (MAD) chart for working near the electrical lines. The MAD charts can be found in the ANSI Z133, section 4.
Work Positioning – When working in the tree or bucket in close proximity to electrical wires, the arborist should always face the electrical lines. Ground workers must also set up the jobsite to avoid any guy wires. Simply place cones to create a visual barrier so a team member does not trip over or walk into a guy wire. REMEMBER THAT LESS THAN ONE AMP CAN KILL A PERSON, so no matter what wire (house service wire, cable and telephone lines, secondary and primary wires) runs through the jobsite, all workers must respect that wire. Being aware of work positioning when working near electrical lines will help prevent:
Contact – Obviously, avoiding direct contact with wires is paramount, but indirect contact can be just as dangerous. Indirect contact occurs when something the arborist touches is energized: for example, a branch that is contacting an energized wire or other object. Every arborist must ALWAYS KEEP THE WIRE IN FRONT OF THEM to avoid direct or indirect contact with a wire.
Arcing – Arcing or arc flashing is discharge of electricity caused when wires from different phases are touching or an electrical explosion happens due to a fault in the system. Proper distancing from electrical wires will reduce the risk of injury or death due to arcing.
Step Potential – Step potential is another monster when talking about electricity. Step potential is a voltage difference between the worker’s feet and the electrical grounding object. It can occur when the bucket or truck comes in contact with an electrical wire, thereby changing the electrical path and making a very dangerous situation for the ground worker. Because of this, each crew member must remember to NEVER TOUCH THE BUCKET TRUCK WHILE IN OPERATION NEAR ELECTRICAL LINES, EVEN TO GET A TOOL OUT. Step potential can also occur near guy wires, which is why all guy wires should be discussed during the job briefing and marked when the jobsite is being set up.
Equipment & Vehicles – Every crew member must also recognize that equipment like gaffs, spurs, or chainsaws can be conductive. Some equipment is labeled “non-conductive” however this does not mean it is electricity safe. Ropes, wooden/fiberglass ladders, fiberglass or wooden pole pruners, and hydraulic saws all are listed as non-conductive. However, they can become conductive if they are dirty or wet, making proper gear inspection vital. For a more detailed article on gear inspection check out this one. Bucket trucks should be dielectrically tested at least once a year; however, that is the minimum. We recommend getting them tested at least twice a year.
Wind – Wind is always a factor while performing tree work, but it is even more important when working near electrical wires. To avoid potential contact or arcing, consideration must be given to how a cut branch or a rope will react with the wind.
Get energized by your work, not electricity! For additional resources on how to institute an electrical hazard training program within your company, reach out to an ArboRisk team member today.
Written by: Dawn Thierbach
and Margaret Hebert