This revision provides the most current and comprehensive safety guidance for arborists in the United States. Although compliance with this standard is voluntary, Z carries the force of law in many instances in the U. One of the most notable changes is in section 4 — Electrical Hazards — specifically the expansion of the rules for working in proximity to electrical hazards to recognize three levels of qualification: the unqualified, the Incidental Line Clearance Arborist and Utility Line Clearance Arborist. This is a sizeable expansion on the topic from the previous version, and specifically details the safety requirements of each of these tree worker positions.

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It is intended as a guide to federal, state, and local authorities in drafting their regulations and may be adopted in whole or in part. See Annex D, Additional Resources, for a list of these and other applicable informative references. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated in Annex D.

However, only one trained person need be available if all new employees are trained in first aid within three months of their hiring dates. Workers shall not place reliance on the dielectric capabilities of such helmets. The employer shall provide employees protection against the effects of noise exposure when sound levels exceed an 8-hour, time-weighted average TWA of 85 decibels dB.

Further resources or research may be necessary to locate underground utilities on private properties. The briefing shall be communicated to all affected workers. An employee working alone need not conduct a job briefing. However, the employer shall ensure that the tasks are being performed as if a briefing were required. Hand signals or whistles may also be used. Eye contact with, or line-of-sight between, the arborist aloft and the ground person should also be established when communicating.

Communications among arborists aloft and other workers on the ground shall be established before commencing operations.

Predetermined, non-verbal communication such as whistles, two-way hand signals, or radios may also be used. Spilled fuel shall be cleaned up before restarting. Federal requirements are explained in 36 CFR The following steps should be followed when this condition is present: a Climbing of trees in such condition should be assessed by a qualified line clearance arborist and supervisor to determine whether or not an electrical hazard exists and mitigation is necessary before performing arboricultural operations.

Climbing of trees in such condition should be avoided. This information shall be provided to the host utility within two working days after discovering the hazardous condition.

To prevent operating the equipment prior to repairs, the defects shall be documented and documentation made visible for other operators. The inspection record shall not be removed until the repairs have been made and the equipment is safe to use.

If hazards cannot be removed, the hazards shall be flagged, marked, or otherwise identified, and the operator shall be made aware of the hazards prior to proceeding.

If a written pre-job briefing exists for the work being completed, identified hazards shall be documented. All outriggers shall be properly set on pads before the aerial device is moved from the boom rest cradle. Carabiners and snap hooks shall not be linked together unless designed to do so and accepted by the manufacturer.

At no time shall work be performed while an arborist is secured to both the aerial device and the tree. Either form of electric contact can be fatal. The operator shall be informed of the location of the manual and familiarized with the controls, safety devices, and operating characteristics of the work platform being operated. The operator and other workers shall develop, communicate, and implement a work plan to mitigate the hazards identified on that worksite.

These access panels shall not be opened or unsecured until the engine and all moving parts have come to a complete stop and the ignition key removed and pocketed see Annex C.

Chippers with a mechanical infeed system shall also have a hopper not less than 85 inches 2. Side members of the infeed hopper shall have sufficient height so as to prevent workers from contacting the blades or knives during operations. The activating mechanism for the quick-stop and reversing device shall be located across the top, along each side, and close to the feed end of the infeed hopper within easy reach of the worker.

If maintenance is needed, all moving parts shall come to a complete stop and keys shall be removed from the ignition and pocketed by the authorized person before proceeding. See Annex C. At no time should any part of the body be used to locate leaks or damaged sections of hose.

Enclosures and guards shall be kept in place when the grinding wheels are rotating or cutting. All work shall be in compliance with federal, state, and local underground facility protection laws e. Rigging equipment shall be inspected before each use in accordance with OSHA A spotter shall be used when work is being performed that could encroach on minimum approach distances from energized conductors.

The spotter shall be positioned to effectively gauge the clearance distance and give timely information to the qualified crane operator. Controlled load lowering shall be used. Shock-loading shall be avoided, and free fall is prohibited. A job briefing shall be done before any work begins in accordance with Subsection 3. The following procedures shall be followed when a qualified arborist is to be hoisted by a crane: 5.

During hoisting operations, there shall be no sudden acceleration or deceleration of the moving load. Possible alternate methods include, but are not limited to a the qualified arborist securing to the tree and detaching from the crane before it comes under load; b using a second crane; c using an aerial lift device; or d using an adjacent tree. The load weight estimate shall be communicated to the crane operator. After the pick is complete, the crane operator should verify, compare, and communicate the estimated weight to the qualified arborist.

The suspended load should not exceed 75 percent of the load chart capacity of the crane. Radio communication shall be hands-free. When deadman controls are not available, the worker shall disengage the power source to the rotary or cutter head before dismounting.

Additional inspections shall be performed during winch line use, where service conditions warrant. Damaged or defective winch lines shall be immediately removed from service. Damaged hooks or attachment assemblies shall be taken out of service. The winch shall not be used until complete repairs are made to damaged or missing bolts and hardware. The vehicle shall not be backed up unless the vehicle has a reverse signal alarm audible above the surrounding noise level or when a spotter signals that it is safe to do so, or, immediately before backing up, the driver determines through a visual walk-around inspection that there are no people or obstructions in the path of the vehicle.

Defects or malfunctions affecting the safe operation of equipment shall be corrected before such equipment is placed into use see Annex C, General Safety Procedures That Apply to All Tree Work. The safety chains shall not be twisted or knotted when connecting or when connected to the tow vehicle. Equipment shall meet the towing capacities necessary for the intended load. The equipment props should be accessible without reaching between the raised part of the equipment and the chassis or body of the equipment.

During winching operations of loads that do not have a manufactured attachment point, the load should be secured using a sling. Therefore, loads shall be pulled in line with the winch unless the winch is properly equipped with a fair lead and the operator is trained to pull loads at an angle. Once the material has been positioned the winch line must be properly stored before continuing chipping operations.

Pre-arranged, two-way hand signals may also be used. Workers shall stay out of the drop zone until it has been communicated by the qualified arborist, qualified arborist trainee, or worker aloft that it is safe to enter.

Exposed metal sockets shall not be used. Chain saw safety devices shall not be removed or modified. A chain saw shall be started with the chain brake engaged and the operator holding the saw firmly in a manner that minimizes movement of the saw when pulling the starter handle. Using two work-positioning lanyards or both ends of a two-in-one work-positioning lanyard shall not be considered acceptable as two means of being secured when using a chain saw in a tree. The chain saw shall be carried in a manner that will prevent operator contact with the cutting chain and the muffler.

The chain saw shall not be used in a position or at a distance that could cause the operator to become off-balance, have insecure footing, or relinquish a firm grip on the saw. A chain saw shall not be used above shoulder height unless the employer demonstrates that a greater hazard is posed by operating the chain saw that way in that particular situation. See Subsection 8. Tools other than ropes or throwlines shall not be thrown into a tree or between workers aloft. Arborists should raise or lower hand tools and equipment in a manner such that the cutting edge will not contact the arborist climbing line or handline.

Tools with damaged heads shall not be used. Except when on mobile equipment, ladders should be stored under suitable cover, protected from the weather, and kept in a dry location away from excessive heat. A carabiner shall be capable of withstanding a 5, pound Communications among arborists aloft and other workers on the ground shall be established before cutting and dropping limbs.

Pre- arranged, two-way hand signals may also be used. Arborists and other workers returning to the drop zone shall be acknowledged by arborists aloft. Pole pruners or pole saws shall not be hung on electrical conductors or left in a tree unattended.

Pole saws and pole pruners shall be hung so that sharp edges are away from the arborist and shall be removed when the arborist leaves the tree. Folding hand saws, when not in use, shall be stowed in a manner that protects the worker and others from the cutting edge. Rigging practices shall conform to the requirements in Section 8. When dry conditions exist, arborists and other workers shall not smoke while working in or near dead palm fronds.

All chain saws used under such conditions shall have mufflers and spark arresters in good working condition. Arborists performing this work while climbing shall be supported by an arborist climbing system, and when possible, positioned above the skirt.

Arborists should not remove palm skirts by positioning themselves below the frond skirt or between the palm skirt and the trunk of the tree. If it is determined that the tree poses a risk of failure due to the forces and strains that will be created by the design of the rigging operation, an alternate plan shall be used. The work plan and the tree shall be considered relative to the forces being applied to any part of the tree, including branch attachments and anchoring roots, before a rigging point is chosen and established.

The system components shall comply with working-load limits relative to the operation and the maximum potential forces.

Rigging equipment shall be chosen for the specific task based on working-load limits and design specifications. Rigging equipment and its connecting links shall be inspected immediately before use and removed from service if found to be defective, damaged, or overloaded.

Options may include: Use of a backstay to support the load-bearing rigging point by placing an appropriately rated rope from the limb used as the load-bearing rigging point back to a higher point on the main trunk of the tree or other higher and suitable limb; or Installation of an additional and separate rigging system that utilizes supporting members, other than those already in use by the primary lowering point, in an effort to have both rigging systems share the load force.

The verbal, audible, or visual communication system shall use an established command and response system see example or pre-arranged, two-way hand signals.

The communication method shall be clearly understood and used during all rigging operations.


ANSI Z133.1



Z133 Industry Standards


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