Safe Work Practices and ANSI Z133: What the ISA Exam Tests

Domain Review: This topic is one of the [10 ISA exam domains](/blog/isa-arborist-exam-domains-explained) you must master.

Safety is the highest-weighted domain on the ISA exam (15%). If you fail safety, you fail the test. The exam is based entirely on the ANSI Z133 Safety Standard.

"Shall" vs. "Should"

• Shall: Mandatory. (e.g., "Leg protection shall be worn while operating a chainsaw.")
• Should: Advisory. (e.g., "Cut-resistant boots should be worn.")
• Exam Tip: If the question asks what you "must" do, look for the "Shall" rule.

Electrical Hazards

• Qualified vs. Unqualified:
  • Unqualified: Most arborists. Must stay 10 feet away from distribution lines (up to 50kV).
  • Qualified: Specialized training (Line Clearance Arborist). Can work closer BUT still maintains a MAD (Minimum Approach Distance).
• Indirect Contact: You don't have to touch the wire to die. If your branch touches the wire, or your tool touches the branch that touches the wire, you are part of the circuit.

Chainsaw Safety

• Two Hands: You must operaate the saw with two hands at all times. "One-handing" it is a violation.
• Kickback Zone: The upper quadrant of the guide bar nose. Contact here causes the bar to snap back at the operator.
• Starting: Drop starting is prohibited. You must have two points of contact (ground or leg lock).

Chipper Safety

• Feed Angle: Feed from the side, not directly behind.
• PPE: No loose clothing (hoodie strings, gauntlet gloves) that can get snagged.
• Winch: Don't stand in the bight (the loop/zone of a potentially snapping rope).

Aerial Rescue

• Protocol:
  1. Assess the scene (Electrical?).
  2. Call 911.
  3. Secure the victim (if safe).
  4. Lower properly.
• Key Concept: Never become a second victim. If the tree is energized, do not climb it.

Summary

When in doubt on a safety question, pick the most conservative option. "When can you enter the drop zone?" Answer: "Only when the climber gives the audible signal."