Note: The following article includes the proposed changes to “Section 3, Electrical Hazard” of the ANSI Z133 safety standard. This next Z edition will be published during 2024, and these “Electrical Level” categories will be subject to change.

Arboricultural operations are often conducted within a multitude of hazards. The daily life of an arborist is spent safely navigating these hazards – from passing traffic to overhead power lines – by following company safety policies, OSHA regulations and the ANSI Z133 safety standards. Overhead power lines are an ever-present hazard to most arborists. Unless one is working in a community with the utilities buried, trees and power lines often share the same space, with branches and lines almost intertwined.

Initial inspection

Looking for electrical hazards on the job site begins when the job is sold. The sales (consulting) arborist should note any overhead power lines on the job site. There are two important reasons for this initial inspection.

First, unless the work is being performed as a line-clearance operation on behalf of a utility, the utility must be notified before conducting arboricultural operations within the minimum-approach-distance (MAD) category for the crew. The tree company should keep a record of any of these notifications, noting the date, time, request and response.

Second, if the proposed arboricultural operations will be conducted in a tree closer than 10 feet from communication, secondary or primary lines, then it cannot be performed by Electrical Level 1
Arborists, referred to as unqualified arborists under the current 2017 ANSI Z133. These arborists have only a fundamental knowledge of electricity and the electrical delivery system. They also lack the verified skills to safely work within 10 feet of these lines. There is no point in sending a crew out on a job they are not qualified to perform.

Arborist qualifications

If the job involves working near communication and secondary lines, i.e., the tree owner requested the branches be cleared away from the service drop, then it can be performed by an Electrical Level 2 or 3 Arborist. Clearing space around a service drop is a common request from tree owners. The service drop to the house and all communication lines are usually not cleared of tree branches by the contracted line-clearance arborists unless necessary to reach the primary space. This is not universal, however, and before tree crews begin clearing space around service drops at the request of the property owner, the utility should be contacted to see if they will, and prefer to, do this work.

If the arboricultural operations involve working within 10 feet of the primary lines, then the work must be performed by an Electrical Level 3 Arborist. If the job involves working near primary lines with a maximum nominal voltage greater than 35 kV, then the company must present an abatement plan to the utility. The utility may agree to the plan, modify the plan or decide to have some or all of the work performed by their line-clearance crews. This is another reason the sales arborist should inspect the job site for electrical hazards.

The line-clearance arborist

The Electrical Level 4 Arborist, the qualified line-clearance arborist, has not been included in this discussion of the responsibilities of the sales arborists. Electrical Level 4 Arborists are working on behalf of the utility, not the tree owner.

This does not mean utility line-clearance arborists are not interacting with tree owners. The vegetation-management contractor may have personnel going ahead of the crews to obtain permissions. But the tree owner is not directly paying for the work; the work is being done and paid for by the utility owner or operator.

There are tree companies that do residential/commercial tree pruning and removals and have utility contracts. If an arborist for one of these companies moves to a residential/commercial crew from a line-clearance crew, they are no longer an Electrical Level 4 Arborist nor fall within their minimum approach distances and other standards. The employer could verify they have the knowledge and skills for an Electrical Level 3 Arborist, and the arborist would then work within these standards.

State variations

An important note regarding these Electrical-Level categories: They may not be recognized by the state. There are 22 state plans – which are OSHA-approved health and safety programs – across the country.

California Division of Occupational Safety and Health (Cal/OSHA), for example, has the 10-foot requirement; tree workers (as they are defined) must not conduct arboricultural operations in trees with branches within 10 feet of the overhead power lines. They allow qualified tree workers to perform work within 10 feet of lines with a nominal voltage of 600 volts or less, but qualified tree workers must maintain 1 foot or more from these lines. Lines with a voltage greater than 600 volts are the responsibility of the qualified line-clearance tree worker.

Different states, different rules

Other state agencies, such as Maryland Department of Labor (MOSH), have a requirement that a distance of at least 10 feet be maintained between the tree-worker’s body and tools and the energized conductor, unless the scope of the work fits within OSHA regulations 29 CFR 1910.268 and 1910.269. If this distance cannot be maintained, then the system owner/operator must be contacted to de-energize the lines.

Michigan OSHA (MIOSHA) has two categories of arborists. The tree worker – an employee who does tree pruning, trimming, repair and/or removal – and the qualified line-clearance tree trimmer – an employee trained to work in the proximity of energized conductors. The qualified line-clearance tree-trimmer definition for MIOSHA is not limited to an employee for the utility or communication company.

Under MIOSHA, a tree-worker’s body or tools may not be closer than 10 feet to any power line with a voltage greater than 750 volts. If they must work in a tree that would require them to violate this minimum approach distance, then the utility system owner or operator must de-energize the line or provide another solution.

These brief explanations of the California, Maryland and Michigan regulations are meant only as examples. Arborists should be familiar with any state-plan regulations for the states in which they work.

Standard operating procedures

Standard operating procedures (SOPs) are written instructions to guide workers in the safe completion of routine operations. These are prepared with a thorough understanding of the hazards and risks to specific operations, as well as relevant regulations and standards that cover these operations. They must be clearly written. “Don’t write so that you can be understood, write so that you can’t be misunderstood,” reads a quote credited to William Howard Taft, but attributed to many others.

The SOPs provide the framework for the crew to complete any of the numerous activities that are part of our work, from chipping brush to manual tree felling. No two trees or sites are the same. Having set procedures provides the guidance to safely complete common tasks on the job. The SOPs also are useful for training. They should be reviewed annually to stay current with technological changes, as well as changes in regulations and standards.

There are three key procedures for arboricultural operations: a job-hazard analysis, a work plan and a job briefing.

Job hazard analysis

The job hazard analysis (JHA) is all encompassing, from a possibility of an assault from a neighbor already annoyed about the work – an arborist recently had a homeowner from the adjoining property of the work site draw a pistol – to weather-related threats, such as the forecasted heat index. But two major hazard sources are trees and overhead power lines. Being struck by a falling tree or branch, falling with a failing tree or suffering electric shock represent about half of all the fatal incidents to tree workers in the United States.

The tree inspection starts with the sales arborist. This is not a detailed inspection, but enough to match the tree hazards to the capability and equipment for the crew. No one likes appearing at a job site ill prepared. Arriving at a job and finding the need for a lowering device and ropes that were not issued is frustrating and inefficient. It also can make for an unsafe environment as crews try to improvise. A brief description of the tree hazards and the needed equipment to conduct the assigned arboricultural operation helps the crew leader anticipate what the work will entail.

Once the crew arrives on the site, a more detailed tree inspection is completed. The tree inspection is a top to bottom, 360-degree inspection of the tree for defects and conditions. This is different from the levels of tree assessment used for the Tree Risk Assessment Qualification (TRAQ). TRAQ is focused on the likelihood of the tree or a tree part failing and the consequence of a failure. While there are similarities, the JHA considers the risks of working on the tree. Most JHA inspections start with the canopy and work their way down.

Canopy inspection

The canopy inspection is usually performed from the ground. Some basic requirements for the inspection are looking for hangers – branches that are detached and lodged in the canopy – or dead branches that may break free during the work. Cracked branches may carry the same risk.

The profession has seen incidents where the chain-saw operator completed the back cut and began moving along the retreat path only to be struck by a detached branch that falls as the tree moves. We also have had portions of the canopy snap free during a fall, then strike and detach a primary line that then landed on a ground worker.

The canopy also should be inspected for decline and dieback. While dead branches are a canopy hazard, they are also indicators that the stability of the trunk or roots may be compromised. A common statement by a crew that witnessed their climber killed in a fall with a failing tree is that the tree looked fine, but they never inspected it.

Trunk inspection

The trunk should be inspected for structural integrity and its capacity to withstand any forces imposed by the arboricultural operation. A removal crew must consider whether there is the possibility that the fall path, intended or unintended, may strike an overhead power line.

The inspection includes looking for cavities or other signs of decay, including fungal fruiting bodies such as conks or mushrooms, on the tree or adjacent soil. Depending upon the planned work, the extent of any suspected trunk decay may have to be estimated by sounding or probing.

The inspection should be made along and up the trunk to look for included bark between two co-dominant stems. The attachment may be weak and fail during pruning, dismantling or felling. Cankers, a separation of the wood, are also a concern, especially long vertical cracks that occur on opposite sides of the tree. These are also indicators of weaknesses that may lead to failure during pruning, dismantling or felling.

Root inspection

The roots are the most difficult to inspect, and their integrity is usually based on the presentation of the canopy and trunk. Cavities also may appear at ground level. These are indicators that decay may be extending into the roots.

Fungal fruiting bodies, either conks near the ground or mushrooms in the soil near the root flare, are also indicators of the possibility of decay. But identification of the fruiting bodies is important to determine the seriousness of any threat. Recent construction near the base of the tree also may have severed roots, resulting in reduced stability.

Overhead power lines

If there are overhead power lines present on the site and in the vicinity of the arboricultural operation, these must be identified and their nominal maximum voltage determined. While the focus is usually on the overhead lines, underground utilities should not be ignored. The most common sign for those to be noted during an inspection is the presence of a pad-mounted transformer on or near the job site.

Finally, all guy wires should be identified. While these are not designed to carry a current, they are part of the electrical delivery system and should be considered energized with potentially fatal voltages (current) under fault conditions.

Any communication and secondary lines should be identified. These are the lowest lines on the pole and are often larger diameter than the electric supply lines. They also may have coils of line attached near the pole or sno-shoes (slack-storage devices) along the lines. (See photo) There may be junction boxes or amplifiers on these lines, usually near the poles. They also are often attached directly to the pole by a clamp, not an insulator.

The secondaries are strung on insulators, but these are often spools, not the pin type. They may be configured as an open secondary with two 120-volt lines and the neutral, or as a triplex where the two secondaries are wrapped around a neutral that supports the weight of these conductors. Triplexes commonly are service drops, running from the transformer at the pole to the mast on the building. There are still open (bare-wire) secondary lines running from the pole to the building in older sections of many towns.

Primaries

The primaries are the highest lines on the pole. These are supported by pin-type or post insulators. (See Part 3 of this series) The maximum nominal voltage is estimated to determine the appropriate minimum approach distance. Nominal voltage is the voltage intended for usage; it is not necessarily the operational voltage, as that varies.

The type, size and height of the insulators can be used to broadly estimate the maximum nominal voltage. But the most accurate way to determine the maximum nominal voltage for the lines is to ask the utility or system operator.

While the tree and overhead power lines are key hazards in the inspection, other potential hazards are traffic, the presence of pedestrians, soil conditions, site obstacles (such as downspouts) and weather. A written hazard analysis should have the name of the person conducting the evaluation, the date and the appropriate personal protective equipment (PPE) identified. It also should direct that a first-aid kit be available at the job site to address potential injuries from the work being conducted.

Work plan

The crew leader needs to develop a work plan. The plan includes delineating a work zone and how vehicular and pedestrian traffic can be alerted to the presence of the zone though signage, cones or flagging. The plan includes where equipment such as chippers will be staged and how the site should be entered and exited.

The work procedure and the sequence of activities need to be planned to reduce exposure to power lines. A procedure must be in place for response to any incident, electrical or otherwise. The plan includes placement of the first-aid and aerial-rescue kits. Also, it should specify who is designated to make the call to 911 and their alternate if the designated worker is the injured party.

Job briefing

A job briefing is done at the beginning of each job. The job briefing is conducted with all the workers involved in the operation and anyone who comes to the job after the work begins. The hazards associated with the operation, the work procedures, electrical hazards, special precautions, job assignments and the proper use of PPE all need to be communicated.

The company’s SOPs, the specific job’s JHA and the work plan make up the foundation of the job briefing. The job briefing must be communicated to all the workers, but it does not have to be in writing. OSHA does not yet have a tree care standard; however, the OSHA Electrical Power Generation, Transmission and Distribution eTool states that having a written record of job-briefing forms signed by everyone is a good practice. It provides a record that hazards have been identified and a work plan generated, and that it was communicated to all the workers.

What next?

Once the JHA, work plan and job briefing are completed, the crew can begin the job. How they can work near lines will be covered in the next article in this series.

John Ball, Ph.D., BCMA, CTSP, A-NREMT (Advanced-National Registry of Emergency Medical Technicians), is a professor of forestry at South Dakota State University.