Downed power lines and blown transformers have been blamed for several of the deadly fires that have burned around the state in recent years.
About 7,700 homes were destroyed when flames hit Paradise, a former gold-mining camp popular with retirees, on November 8.
Since most of the town of Paradise has been wiped out, an emergency operations center has been set up in nearby Chico, where emergency management officials from San Francisco and Sonoma Counties are trying to help evacuees.
A man discovered a horse that was "shivering uncontrollably" after hiding in a pool to escape the devastating Camp Fire in Paradise, California.
In total 100 National Guard troops have joined cadaver dogs, anthropology teams and mobile morgues in the search for those killed in the flames.
A spokeswoman for CPUC told local media the probes would "assess the compliance of electric facilities with applicable rules and regulations in fire impacted areas".
The "Camp Fire" has destroyed more than 6,500 homes and 260 commercial properties.
Another two people died in the separate Woolsey Fire that has destroyed 435 structures and displaced about 200,000 people in the mountains and foothills near Southern California's Malibu coast, west of Los Angeles.
Camp Fire death toll now at 48, worst in state history
The Woolsey fire in the south has so far killed two people and damaged a number of beach resorts. That problem may be responsible for those deaths and thousands of destroyed structures.
But state fire investigators have not yet determined the utility's culpability in the Tubbs Fire, which killed 23 people and destroyed almost 5,600 structures in California wine country, where losses could top $10 billion.
"In an effort to better inform the public, this list of reported missing persons is being provided", a message on the sheriff's website says.
That blaze has scorched 39,000 hectares of chaparral-covered rolling hills and canyons spanning Ventura and Los Angeles counties, an area roughly the size of Denver. Company spokesman Jason King said, "Nothing is more important than the safety of our customers, employees, contractors and the communities we serve".
The 42 dead in Northern California surpassed the deadliest single fire on record, a 1933 blaze in Griffith Park in Los Angeles.
Hill said the group he was with scrambled to unhook the pool cover, pull the horse to the shallow end, and guide her up the pool steps.
"Last spring they had some good rainfall, which causes a lot of growth, but once the water shuts off, everything dries out again", he continued.
'The humidity will go way up - it will help lay down the fire and help the fire crews to make faster progress on it'.
"We're finding remains in various states", he told reporters. "This declaration will help ensure that Americans who are threatened by these risky wildfires and who rely on Medicare, Medicaid, and the Children's Health Insurance Program have continuous access to the care they need", Azar said in a statement.
On Monday, President Donald Trump - at the request of state authorities - declared that a "major disaster" exists in California.