It's the largest power outage in three years.
An estimated 86,000 homes and businesses lost power Tuesday night.
The source of the widespread power outage has been traced to the Texas Municipal Power Agency power plant at Gibbons Creek in Grimes County.
The Carlos plant is connected to the ERCOT grid and several local energy providers were directly affected by the massive failure at TMPA.
According to area sheriff's departments, parts of Brazos, Madison, Robertson, Burleson and Grimes Counties were without power.
"It's rare to see something like this," Rich Gurley, TMPA Transmission Manager said. "I have seen it a few times in my career, but it is a rare occurrence."
The source traced to a mechanical failure at the TMPA power plant at Gibbons Creek.
Officials say it was a small explosion that caused a widespread problem.
"The failure of a voltage transformer in the substation that caused a short circuit of severe magnitude which caused the trip- out of the large power transformers which then tripped the substation out of service," Gurley said.
The Gibbons Creek Substation is in the path of major power transfer from Dallas to Houston.
The facility takes high voltage power off of the grid and converts it to a lower voltage, it's then transmitted to local electrical companies.
The explosion interrupted the flow of power to about 86,000 customers.
And the cause has yet to be determined.
"We want to investigate it to find out if there's any other equipment of this same type that might be vulnerable," Gurley said. "If there is, we want to get it off the system to prevent further outages."
The investigation could take up to three weeks.
Until the cause is determined, TMPA officials say it could happen again.
And the power outage could be just as widespread.
Local electrical companies are addressing the need for an upgrade in the transmission system supporting the area.
A similar outage at the Gibbons Creek facility in April of 2003 affected about 68,000 local customers.
After that incident, ERCOT recommended a multi-million dollar project to upgrade the transmission system.
The project should be completed by 2009.
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