One of the hazards associated with the use of a tree truck is electrocution. This is why there is a Minimum Approach Distance (M.A.D.) set by the Occupational Safety and Health Administration (OSHA). This standard states that employees should maintain a minimum distance from conductive or live overhead lines. There is an exception to this rule which allows workers to get closer to high voltage transmission systems if the equipment they are using is well insulated or if they wear personal protective equipment (PPE) such as leather gloves, insulating sleeves, and flame resistant clothing.

Qualified Arborists

In a tree trimming operation, arborists should become a qualified person as required by OSHA 29 CFR 1910.269. In order to be qualified, the candidate must be knowledgeable and demonstrate their aptitude in performing the tasks in a cautious way during the duration of their training. Furthermore, individuals who trim trees near power wires should be certified at different levels of training.

It is also required that a qualified person knows how to recognize electrical hazards while working near live power lines. Arborists reach tall trees by using a tree truck, which is a modern technique for cutting tree limbs. When using this method for trimming trees, a Minimum Approach Distance (M.A.D.) of ten feet from transmission lines must be maintained.

The Ten-Foot Rule

There are cases where workers may need to work less than ten feet from the voltage lines. Not all arborists have the proper training and experience in this area of tree work. These people require an additional level of training and need to meet certain qualifications to be able to work safely and efficiently around trees. Those people who pass the training and meet the qualifications are not necessarily considered as a qualified line-clearance arborist (QLCA) or a qualified line-clearance arborist trainee (QLCAT) unless they are certified by their employers.

• QLCA – This is a person who has undergone training and has experience in recognizing hazards and demonstrating special techniques when working near energized conductors.

• QLCAT – This is a person who is currently undergoing line-clearance training under the direct supervision of a QLCA. The trainee should demonstrate skills and techniques when working near energized conductors during the entire length of the training.

Safety Requirements

Occupational Safety and Health Administration (OSHA) ANSI Z 133.1-2006 describes all the safety requirements of arborists. This standard states that traffic and pedestrian control must be established before doing the job. First-aid kits must be accessible and easy to locate, and should be provided by employers. Additionally, qualified employees should utilize personal protective equipment (PPE) at all times and employers must assess the working area to determine what type of PPE is necessary to use for worker protection. With regards to electric hazards, workers must be educated about the way in which the human body is a good conductor of electricity as well as phase-to-ground contact and phase-to-phase contact.

When using aerial devices for tree trimming near power lines, extreme caution must be observed and safety cannot be neglected. There are certain standards that have been set by state and federal agencies, all of which are directed at the protection of both the employee and employer. By complying with safety standards, workers can ensure their safety from any potential hazards. Remember, don't be M.A.D. - be safe!