ANSI Z133 Safety Standard for Tree Work

ANSI Z133 is the American National Standard for safety requirements in arboricultural operations. It covers climbing, rigging, chainsaw use, electrical hazards, traffic control, and personal protective equipment for tree workers.

What's inside Z133

Z133 sets minimum safety requirements for tree work. It covers general safety and job briefings, electrical hazards and approach distances, vehicles and mobile equipment, portable power tools and chainsaws, hand tools, work-positioning and fall protection for climbers, rigging, felling, and PPE. People also search for it as Z133 or anzi z133; it is the same standard.

Many employers and insurers treat Z133 as the baseline for how their crews work, and OSHA may reference it in enforcement.

It also covers job briefings, work zones and traffic control, chippers and stump grinders, aerial lifts, cranes, and emergency response, which makes it useful for ground crews as well as climbers.

Using it on the crew

Keep a copy on each truck and use it in tailgate meetings. Go through the climbing and rigging sections with new hires, and refer to it when you choose gear such as ascent and descent devices. Reading the standard does not replace hands-on training; pair it with qualified instruction. For tree care practices, see ANSI A300.

Many crews mark up a copy with tabs for the sections they reference most, such as approach distances and rigging, so answers are easy to find during a job briefing.

New climbers should read the climbing and rigging sections early, and crew leaders should revisit the electrical section often.