Electrical District No. 3 officials have identified the insulator responsible for an unprecedented outage that killed power to nearly all of Maricopa last month. Upon further inspection, it seems a naughty little balloon might be the killer.
The April 23 outage left Maricopa powerless for more than two hours and was mostly centered within city limits, although unincorporated Maricopa and parts of Casa Grande suffered, too.
“It is probable that the fault started at the insulator and that it may have been impacted by airborne material,” said ED3 Diana Perkins, adding that a plastic material was found burned up near the insulator.
It is unknown whether the fire was caused by a mylar balloon, which are notorious for causing sparks to fly and fires to ignite when they hit power lines.
Mylar balloons are banned in wildfire-prone California and several other states because they conduct electricity and are a common cause of power line fires. While they are not banned in the state, Arizona Public Service is among utility companies telling consumers that mylar balloons pose a potential fire danger when they float into power lines.
“ED3’s inspection found visible arcing on an insulator at Maricopa Substation,” Perkins said. “The insulator has a 40-year useful life and was installed new in 2023 when Maricopa Substation was rebuilt at a cost of more than $4.1 million.”
The insulator was replaced as a precaution, Perkins said.
The Maricopa Substation is at White & Parker Road, just north of the Nissan Proving Ground.
ED3 worked with APS and the U.S. Western Area Power Administration to repair damage.
The power utility reports it is still reviewing the outage that occurred at 6:41 a.m. on a Tuesday.
It affected ED3’s 69 kilovolt system and the three transformers at ED3’s power delivery point at the APS Santa Rosa/WAPA Test Track and ED3’s Maricopa substations, Perkins said.
“The insulator may be the location of the initial fault” that occurred,” Perkins said. “No specific foreign debris or plant/animal matter were found onsite on the day of the event at Maricopa Substation. However, the next day during inspections, a long piece of white plastic was temporarily caught in the de-energized overhead bus blown around by winds.”
She said: “The Maricopa Substation transformer was tested and “was deemed to be in normal condition and was subsequently placed back into service post-event.”
The outage affected more than 33,000 Maricopa power consumers and 150 APS customers.
Nothing was found to indicate an issue with APS equipment, Perkins said.
“APS is committed to engaging regularly with ED3 and is currently collaborating in a joint review of the grid’s protection systems to strengthen and improve resiliency,” Perkins said.
She said APS and WAPA continue to collaborate with ED3 as the parties reviewed maintenance records and completed additional inspections.
Perkins said the power agencies continue to discuss additional planning steps for the APS Santa Rosa/WAPA Text Track/ED3 Maricopa substations.
