By Michael “House” Tain
Whether a tree care company does contracts for utility line clearance or not, electricity is part of their daily work environment; and sadly, they may not always realize or recognize it. Electricity is part and parcel of the modern world, with a great many gizmos and whatnot relying on this unseen nebulous force flowing all around through wires and cables. And although most tree folk, when they put their mind to it, will recognize its presence, either aloft or underground, many times electricity either gets “forgotten” or dismissed as not all that dangerous or important. This is a mistake of the highest order for tree care personnel, as dangerous as ignoring large cracks or areas of decay in a tree to be climbed. As Dr. John Ball’s accident/fatality statistics show, it is a mistake that often and regularly takes a toll among tree folk. “Electric,” much like gravity — another force with which tree folk are familiar — “just don’t care.” It will use any conductive path to get back to the ground; and although tree people may not realize it, their bodies are quite conductive, as are trees, ropes, and many of the other tools and gear used to carry out tree care. The rules, regulations and practices of utility line clearance are fairly simple and easy to understand/comply with, but the first step is recognizing that a hazard exists, and electricity is definitely a hazard of the highest order. The next step is following those simple rules, regulations and practices, regardless of whether the crew thinks they can “get away with it this one time.” As mentioned previously, “electric just don’t care,” and given this property, along with its abilities to stop a heart or cook flesh, it’s up to the tree care personnel to care and give electricity the respect and distance it requires.
Line clearance or tree work
Although this is pretty straightforward at first glance, it can get more complicated and nuanced in the day to day world of trying to get a tree job done. After all, very few residential tree care company owners would think of their crews as doing “utility line clearance,” but it is probably a normal occurrence for crews to be working around at least drop lines or even transmission lines in the regular course of the day. In principle it’s simple — personnel that have not received the required training, education and evaluation that comprises a Line Clearance Arborist or a Line Clearance Arborist Trainee do not get closer to energized conductors than the minimum approach distance. Minimum approach distances will be discussed in greater detail later, but the key number for non-line clearance tree folk to keep in mind is 10 feet, meaning don’t get closer than that to any line; and larger lines with even greater voltage will require greater distances.
How close is too close?
The table below shows a variety of minimum approach distances for tree folk who are not line clearance certified. The folks who have had the specialized training and instruction, along with tools and equipment, to be line clearance certified use a different table which takes into account their skills, knowledge and abilities. Confusion is often expressed by tree care personnel in regard to the table — the most common comment being that if they don’t know how much “electric” the line is carrying, how can they know how far away they need to stay? As can be seen from the table, nobody except for line clearance folk should be within 10 feet of an energized conductor. As to how many volts the line may be carrying, a rough estimate may be gained by looking at the number of insulators at the pole — more insulators mean more volts, which means more distance. There are a wide variety of classes and training seminars available that will help tree crews decipher how much “electric” may be in a given line; and most utility/power companies and crews are happy to pass on this vital information to curious tree care crews or companies; after all, they will have to clean up the mess if something goes “zap.” Electricity, given the right atmospheric conditions and voltage levels can easily arc through the air to a crew member who just wanted to get “a little bit closer.” Stay the proper distance away, and keep the gear/equipment the proper distance away, or, if unsure, very far away; and the voltage will not be able to show how badly it wishes to return to the ground through a body or piece of equipment.
Kilovolts phase to phase
0.0 to 50.0
50.1 to 72.5
72.6 to 121.0
138.0 to 145.0
161.0 to 169.0
230.0 to 242.0
345.0 to 362.0
500.0 to 550.0
785.0 to 800.0
Many electrical interactions between tree crews and utility lines happen without the crew even recognizing that “electric” was present. It usually involves a crew, climber or crane/lift operator who hasn’t evaluated the tree and site for hazards. In essence, nobody ever saw the utility line on the back side of the tree or disappearing into the canopy and somebody moves or swings right into it. Direct contact can also happen when the worker knows the line is there, but has gotten busy and has a moment of inattention, and some form of “zap” is the result. Storm clean-up or work situations can also be ripe with direct contact possibilities. There may be any number of lines down, tangled in brush, or settled down on top of trees — all of them “live” and looking for a quick and easy path to the ground. Knowledge of the minimum approach distances, with a good pre-work hazard inspection, will go a long way toward preventing the possibility of direct contact.
Indirect contact paths
This type of path for the “electric” is typically when something unrelated to the worker’s body comes into contact with a line or gets inside the line’s safe approach distance. The electricity travels through whatever this non-body part might be, because it just don’t care, and runs into a human body, which has all kinds of conducting water in it at the end. The conducting non-body part could be any number of things including the tree being climbed, branches, conductive tools or lifts, and even climbing or rigging ropes. In storm scenarios, indirect contact can be conducted through chain link fences, cable lines, and other usually “safe” objects, which can make it very difficult to identify ahead of time. A good pre-work inspection, perhaps more extensive in a storm situation, will help minimize the possibility of indirect contact; but “forecasting” work plan actions and movement will also be helpful. If the desired rigging point might bring the rope within that safe approach distance, then another rigging point is probably a better idea, or even simply examining very clearly the path the branch is going to take to the ground. Keep in mind that the branch that is intended to be “cut and chucked” — even if it’s only gonna pass through that minimum approach distance for a moment — may provide just enough of a path for Mr. Electric to say hello to the climber’s pieces parts.
PPE is different with electric
Folks that aren’t line clearance certified, as already stated, should never be closer than 10 feet to an energized conductor, but there are some aspects of PPE and gear for working around electricity that all tree care personnel should know about. Even if the crew doesn’t feel like the job they are doing is truly a “line clearance job,” the reality is that the presence of energized lines requires greater vigilance and some different PPE/gear choices. A hard hat or helmet that is going to be used around electrical hazards must be E rated; and not have any of those head cooling vents or holes that help keep the melon just a bit cooler. Taking an E rated helmet and putting vents in it immediately destroys any value it may have had around electricity. This rule about putting holes in things also applies to the bucket and its liner, it’s meant to give some additional protection against electric, but drilling holes in it to drain that troublesome water out eliminates that protection. Most gear is going to be conductive to some degree, particularly given the dirt and debris that builds up in it in a short period of time, let alone if any moisture has collected in it; but around electricity, very conductive stuff like wire core lanyards and the like should be avoided. In addition, non-conductive options, such as fiberglass ladders and foam-filled poles, should be used even if it is not technically a “line clearance” job. The material on utility lines is not insulation; and is most likely some form of weatherproofing. No material on the outside of the line should cause tree crew members think it is safe to touch. Think about how much insulation is required around a simple extension cord in the house to protect users, then try to think how much insulation would be required around a line carrying 100 times as much power.
Dirt conducts too
The soil itself, or dirt, will also conduct “electric” if exposed to it; and this is described as a ground fault, when the ground itself becomes energized. This may occur from a downed line, or even when electricity travels through a non-insulated lift and goes through the outriggers. Whatever caused the ground fault, it is not a good situation. The crew member who was leaning against the truck will not even realize that a ground fault has occurred as they will already be trying to figure out what hit them. The area of soil with electricity will vary with moisture, voltage and soil structure, but it will certainly be energized. A crew member stepping from an area of low voltage to an area of high voltage has presented an excellent pathway for the “juice.” Often called step potential, this occurrence can be minimized by taking very small steps, almost shuffling, or hopping with both feet together away from the source. This will decrease the likelihood of being in areas of widely different voltages at the same time. This technique can also be used by operators or drivers of equipment that has become energized to flee the vehicle, though most training states it should be used as a last resort. Although not technically a case of ground fault, tree care companies must be very aware of the possibility of underground utility lines, particularly when carrying out common tree care tasks such as stump grinding, planting, or even root excavation. An underground line will light a crew up just like an overhead line; and “dial before you dig” is an excellent idea prior to any soil-based tree activities.
Electricity, in some shape and form, is part and parcel of almost every tree care work site; and the first step to mitigating its hazards is recognizing the presence of utility lines. The next step is understanding the simple rules and standards governing working around electricity. Although having some line clearance arborists on staff may seem an unnecessary expense, the possible life-saving knowledge and skills make it money well spent. If that option is not possible, then at the least all members of the crew should have regular training in electrical hazard awareness and recognition, because while “electric just don’t care,” tree folk have to.
Michael “House” Tain is a contract climber, splicer, educator and writer associated with North American Training Solutions www.northamericantrainingsolutions.com and Arbor Canada Training and Education www.arborcanada.com. He is currently located in Lancaster, Ky., and can be reached via e-mail at firstname.lastname@example.org.