Five Rules in the Z133 You May Not Know
Regarding the Use of Chain Saws
by John Ball, Ph . D ., CTSP , and Cary Shepherd, CTSP
A chain saw shall be operated with two hands at all times, one hand on each handle with thumbs wrapped around the handles.
Photo courtesy of Chippers, Inc.
Can you recall the first time you used a chain saw? Perhaps you
remember its weight in your hands, the sound of the engine or the
sense of purpose you felt as you planned your cuts. Hopefully,
since that first experience, you’ve learned about chain saw safety. If
you wish to continue learning – as any true professional should –
an amazing manual titled “American National Standard for Arbori-
cultural Operations – Safety Requirements” can help you.
Also known as the “ANSI Z133-2017,” “the Z133” or simply “the
Z,” this manual lists requirements and recommendations for
staying safe while handling a chain saw. It’s considered the gold
standard for proper safety during commercial arboricultural
operations. The Z’s time-tested wisdom is critical knowledge for
industry veterans and novices alike.
The latest edition of the Z was published in the fall of 2017 and
replaces the previous edition, the Z133-2012. The 2017 edition
contains many changes, so it’s important for tree workers to
familiarize themselves with the newer version and its language.
Let’s look at five important rules in the Z that impact your day-
to-day work as a tree industry professional.
1
No drop-starts
Look in Section 6, titled Portable Power Hand Tools, under
Section 6.3, titled Chain Saws. An often-overlooked rule guides
the starting of these powerful tools:
Drop-starting a chain saw is prohibited. (6.3.4)
If you’re a professional tree climber or you work from an aerial
bucket, you may ask, “Then how can I start my chain saw when
10 MAA NEWS / March 2019
I’m in a tree?” The answer is that starting a chain saw in the air
isn’t the same as drop-starting. Drop-starting involves two sepa-
rate motions, pushing the saw away with one hand and pulling
on the starter cord with your other – a maneuver that both lacks
control and could damage your equipment. The correct method
for starting in the air is to firmly hold the saw steady with one
hand and, with the chain brake engaged, pull the cord with your
opposite arm.
Of course, one way to avoid pulling on the cord is to use an elec-
tric li-Ion battery chain saw. These chain saws require only the
push of a button to start and can be started with both hands
firmly on the handles. Starting with the chain brake engaged is
still a requirement for these chain saws.
2
No one-handed cuts
Section 6 is home to another contentious issue with the follow-
ing rule related to one-handed use of a chain saw:
A chain saw shall be operated with two hands at all times, one
hand on each handle with thumbs wrapped around the handles.
(6.3.5)
In the language of the Z, “shall” indicates a mandatory require-
ment – no exceptions. That means no one-handed reaching to
far branches. Subparagraph 6.3.5.1 does allow for reversing the
placement of the right and left hands if an employer (or crew
leader) believes that’s the safer method for a particular operation.
But even in these circumstances, it’s not a decision on the part of
the chain saw operator.