Keiran Dale-Williams has been sentenced in the County Court for his role in the fire, which destroyed a boom lift in Willow Park on March 6 last year.

The 85-foot cherry picker was gutted, with a replacement cost of $186,000 and a further $4000 in damage.

Dale-Williams avoided jail for the incident, which involved the fuel line being severed.

The 20-year-old helped set it alight and the group watched as it burned.

Judge Richard Smith said there was no logic to the offending, as he ordered Dale-Williams to perform 200 hours of community work.

It followed an incident about a month earlier where he damaged a vehicle parked in a driveway on De Kerilleau Drive.

"I can only infer that you are a person who obtains some bizarre pleasure or satisfaction in damaging expensive items of property belonging to other people," the judge said.

"I consider that your destruction of the machine was an act of pure and senseless vandalism."

The group involved in the incident had been roaming the area in search of a car to steal.

They found the boom lift, owned by Lavington business Skylift Hire.

The machine was being rented out to Positive Electrical Services as part of a council contract to install new lighting at the park.

Those involved covered their hands and tried to start the machine, and torched it when they were unable to do so.

Dale-Williams initially denied involvement but later made some admissions to the offence.

He was assessed by a psychologist before being sentenced, and Judge Smith noted his issues.

"Your prickly temperament and problems with emotional and behavioural regulation have undermined your ability to sustain employment and social networks," he said.

"She (the psychologist) reported as a consequence, you spend most of your time in your room playing video games,

"She noted that you had expressed to her great regret and shame for your offending behaviour.

"She stated that you didn't present with any pyromanic interests or obsessions, and were unable to explain why you got involved in this offending behaviour."

Judge Smith said the 20-year-old showed severe behavioural issues at school.

He has not worked since leaving in Year 10 and can barely read.

The judge said he had set out to engage in "serious criminal behaviour" before the fire.

"Although you may not have known its precise value, you would have known that this was never going to be minor damage," he said.

"There was no reason at all for your actions."

Dale-Williams must also complete about 40 hours of unpaid community work from other offending.