FOOD processor McCain Foods was fined $145,000 last week after admitting to health and safety failings at its Ballarat plant.

The conviction, under the Occupational Health and Safety Act, related to a 2007 incident in which a maintenance fitter's left thumb was amputated while he was working on a machine that peels and cleans potatoes.

The Ballarat County Court heard that two fitters and an electrician attempted to fix the broken machine, believing it to be isolated through its control switches - when it was actually on a manual setting.

When one of the fitters put his hand in the machine to loosen a chain, the machine started up, amputating his left thumb.

Since the incident, the company has complied with two improvement notices issued by WorkSafe Victoria and developed an isolation lock-out procedure for the machine.

It has also designed labels for each piece of plant, indicating whether or not multiple isolations are required.

In 2008 McCain Foods was convicted by WorkSafe when a pizza shredder started while a maintenance mechanic was working on it.

McCain Foods was also prosecuted for workplace health and safety failings in 1983, 1986, 1991, 2002 and 2003.