WA's energy safety watchdog will investigate causes behind the weekend's blaze near Toodyay, including whether it could have been started by faulty electrical equipment.
Homeowners were briefly put on an emergency warning on Sunday when a bushfire flared just east of Toodyay in blisteringly hot conditions and almost spread out of control.
Although more than 150 career and volunteer bush firefighters quickly managed to contain the blaze, authorities were yesterday still unsure about what had caused it.
The police arson squad was not called to investigate the fire but it is believed investigators from EnergySafety will try to identify the cause and whether anyone was to blame.
The Department of Fire and Emergency Services issued a total fire ban for shires including Toodyay on Sunday, meaning it was unlikely that harvest activity played a role.
Investigators will instead look at whether it was started by natural causes, including lightning and spontaneous combustion, which can happen when piles of mulch or hay overheat.
Among the latter group is electrical equipment failure, given the thousands of kilometres of power poles and wires that span the Wheatbelt and are owned by Western Power.
A Western Power spokeswoman said the utility was co-operating with DFES, EnergySafety and other agencies as they investigated the blaze.
The department said it was too early to tell what had caused the fire and its investigators would return today.
Toodyay Shire president David Dow said he was keen to know what had sparked the fire, given events of recent years.
In 2007, a young female teacher was killed when 22,000-volt power lines owned by Western Power clashed and set off an inferno.
Three years later, a separate fire, which EnergySafety said was caused by a fallen Western Power wood pole, razed 38 homes.
Western Power has always denied it was responsible.
Mr Dow said Toodyay owed a debt of gratitude for the efforts of Sunday's firefighters. "It could have been pretty bad . . . so we're very thankful," he said.
"We'd definitely like to know (what happened) but whether we get an answer or not is in the lap of the gods."