Chippers and stump grinders: what the rules say

This page describes what regulators and standards bodies have published. Numbers are given only as the page states them.

United States

OSHA's Safety and Health Information Bulletin on wood chippers is dated April 16, 2008. It says it is not a standard or regulation, and that it creates no new legal obligations. It is advisory and informational. It is published as the OSHA chipper bulletin.

The bulletin says that 39 employees were killed in chipper accidents from 1996 to 2005, and that 78 percent of those deaths resulted from being caught in the chipper. Most of the rest were struck-by accidents. It says that when workers feed limbs into a chipper, they are at risk of being caught and pulled into the fast-turning knives. It also covers chippers with a winch line, which it says can pose unique struck-by hazards.

The bulletin quotes ANSI Z133.1-2006 as requiring that chippers with a mechanical feed control bar have quick-stop and reverse feed devices for emergencies. That is the 2006 edition as it stood in 2008; the current edition is ANSI Z133-2026, covered in the safety rules by country guide. The bulletin then lists recommended training and work practices. Among them:

One or more employees as a safety watch, stationed near the emergency shut-off devices.
Feeding from the side of the infeed chute.
Proper locking pins to immobilize the disc when clearing a clogged chute or changing blades.

Separately, it lists gloves with no cuffs under clothing that it calls industry and ANSI recommended, citing ANSI Z133.1-2006.

NIOSH published its own chipper hazard alert, Hazard ID 8, in August 1999 as publication 99-145. It says the Bureau of Labor Statistics counted 11 workers killed from 1992 through 1997 while working near mobile wood chippers. In seven cases the worker was caught by the feed mechanism and pulled through the knives. In four cases the worker was struck by a hood that came off a machine after it was opened or closed while the knives were still turning. It states the chipper disc or drum turns between 1,000 and 2,000 rpm. Its recommendations include at least two workers in close contact when operating the chipper, and waiting until all internal parts have stopped before the hood is opened. The page is the NIOSH alert in the CDC archive.

The OSHA page on tree care hazards lists two state fatality reports under the caught-in hazard. One is a New York report, 16NY024, about a 23-year-old worker pulled into a wood chipper on his first day. The other is a California report, 18CA002, about a laborer pulled into a tree stump grinder.

The ANSI Z133 text itself comes from the International Society of Arboriculture, as described in the safety rules by country guide.

Canada

Safety rules are set by each province and territory. The chipper document is a WorkSafeBC incident investigation summary published in July 2005. It says a driven-feed mobile chipper did not have a panic bar to act as an emergency stop device, and that a groundsman could not stop himself being pulled into the chipper blade. The summary says the groundsman was probably working or standing near the front of the feed table, and that his gloves or jacket may have been caught by the branches being chipped. It is on the WorkSafeBC summary page.

United Kingdom

HSE's tree work pages say to ensure that no one uses chippers or stump grinders unless they are trained and competent to do so. See the HSE hand tools page.

Stump grinders

HSE leaflet AFAG606, Mobile stump grinders, was first published in April 2003 and carries a 04/13 date. It says all operators must have had appropriate training in how to operate the machine and carry out the tasks. It says to check the site for underground services, and never to approach the cutting mechanism until it has come to a complete stop. The leaflet is at hse.gov.uk.

Wood chippers

The matching chipper leaflet was HSE AFAG604, which was withdrawn in 2013. Its content lives on as FISA leaflet 604, Wood chippers, reprinted in March 2013. The leaflet says it is based on the guidance previously published in AFAG604. It says to switch the engine off, remove the key and wait for dangerous moving parts to stop before opening any guard or reaching into the hopper or discharge chute, and it specifies a push-stick at least 1.5 m long. A copy is hosted by a training provider as FISA leaflet 604.

AFAG805, Training and certification, says that for certain machinery operations, including chippers and stump grinders, AFAG recommends that operators choose between an integrated training and assessment (ITA) course and an independently assessed training course. It also says following the guidance is not compulsory and you are free to take other action, but that if you do follow it you will normally be doing enough to comply with the law. The copy linked here carries a 05/11 date. See the AFAG805 leaflet.

Australia

Safe Work Australia's Guide to managing the risks of tree work, dated March 2023, says rotating in-feed rollers and the cutting disc or drum are the most hazardous components of wood chipping machines. The copy linked here is hosted on a tree service's site. In that copy:

It describes ropes, clothing or gloves caught on a branch dragging a worker past the safety curtain and in-feed rollers onto the cutting blades.
It recommends guarding at a minimum-reach distance of 1500 mm from the leading edge of the feed hopper to the in-feed rollers.
It says chippers without an in-feed stop control device, or with an in-feed tray under 600 mm high, should be operated by two operators so the emergency stop stays within reach.
It says the hatch should not be opened until the chipper has stopped and the keys have been removed.

For stump grinders, the same guide says they use a rotating cutting disc or wheel to grind stump wood and surface roots to below ground level. Its hazard list includes contact with the grinding disc, ejected material, noise, vibration, dust and live underground services. It lists checking for underground services, through Before You Dig Australia, if the penetration exceeds 200 mm. The call-before-you-dig guide covers that service. The guide copy is at this hosted PDF.

WorkSafe Victoria's woodchipper safety page says woodchippers should be operated by 2 employees to ensure ready access to the emergency stop button. It also says operating teams should have at least 2 employees who are competent with a woodchipper and have received specific training on the individual machine. SafeWork NSW lists a Woodchipper guide, catalogue number SW09408, for trailer-mounted hand-fed chippers on its tree work resource page.

New Zealand

Its guidance on maintaining trees around powerlines says that all chainsaw and brushwood chipper workers, and those nearby, shall wear at least Grade 4 hearing protection, and refers to the Arborists' Code Part 1. The page says the guidance has not been updated to reflect the Health and Safety at Work Act 2015 and its regulations. See the WorkSafe powerlines page.

Training units

The Australian national training register lists AHCARB212, Operate and maintain stump grinding machines. Its scope says it covers the skills and knowledge to operate motorised stump grinding machines to safely remove tree stumps. One of its elements is to identify and confirm the location and depth of above and below ground services with a supervisor. The page shows this release as current from August 26, 2020. See the AHCARB212 listing. For how courses fit together, see the certifications by country guide.

At a glance

Country	Chipper document	Stump grinder document
United States	OSHA SHIB, April 2008; NIOSH 99-145	California fatality report 18CA002, listed by OSHA
Canada	WorkSafeBC incident summary, July 2005	None listed
United Kingdom	FISA 604 (was HSE AFAG604)	HSE AFAG606
Australia	Safe Work Australia guide; WorkSafe Victoria; SafeWork NSW SW09408	Safe Work Australia guide; unit AHCARB212
New Zealand	Hearing protection line in powerlines guidance	None listed

Rules and leaflets change. Which rule applies to a job is a question for the regulator.