The emergency communications dispatch center in Santa Clara County lost the ability to dispatch ambulances and fire trucks for about 90 minutes Thursday night.
The emergency management services director believes a battery backup system failed, tripping the breakers to the dispatch room at about 10:30 p.m.
The building at at 2700 Carol Drive did not completely lose power, but several systems used to dispatch ambulances and fire trucks went down until about midnight. At one point, radios in the parking lot were used to manually dispatch the emergency vehicles.
Despite the problem, no emergency calls went unanswered, according to Santa Clara County EMS Director Michael Petrie.
When the power went out in his dispatch room, Petrie said, the center immediately flipped the 911 calls over to the city of San Jose's dispatch, which is their backup in situations like this.
The center then setup an incident command in the parking lot so they could dispatch those 911 calls with portable two-way radios.
Petrie said a backup battery system for 911 phones, the radios and the dispatch computers failed and for some reason tripped the breakers to the dispatch room, shutting off power to that room while leaving the power on in the rest of the building.
The dispatch room was out of service for an hour and a half while workers searched for the tripped breakers and reset them.
Thursday, Petrie said he was in communication with PG&E and the company that services the backup battery system to figure out what caused those circuits to trip.
The Santa Clara County communications center services about 200,000 people who live in all of unincorporated Santa Clara County and the cities contracted by the county sheriff and fire departments.