Eighty claimants who suffered property damage want $10 million, alleging negligence by Orion and the Christchurch Adventure Park.
Opening the group's case today, Craig Stevens said the Early Valley fire was started by molten metal from a faulting power pole falling on to tinder dry grass.
He said Orion's replacing of this pole just three days later, and its failure to retain crucial parts of it, obstructed the investigation.
"It destroyed the area of origin... it disposed of the vital artefact of the expulsion dropout fuse and, your honour, to lose that it had to be unscrewed."
Stevens also pointed to the Marleys Hill fire, 4km away, which started 90 minutes later, most likely due to arson.
He said this was spread by the Adventure Park continuing to run its chair lift and dropping burning plastic from the chairs on to the ground.
He said this led directly to the fire - which until then had been contained - roaring up the hill and damaging homes on Worsleys Rd.
Stevens said Cecile Grace, who was part of the action, only had time to gather a few clothes and a photo of her late husband, as she fled her home.
Lawyers for the two defendants are due to begin their cases later today.
The trial was scheduled to last nine weeks.
