T Power Outage Caused By Human Error

The MBTA says Thursday’s 30-minute power outage occurred after someone accidentally tripped a main breaker switch on power lines that supply the T's main signaling system. More than 130 trains slowed to a crawl just after peak morning rush hour.

Richard Leary, chief operating officer of the Massachusetts Bay Transit Authority, said MBTA employees and contractors with United Power Group had taken a cable offline for routine preventive maintenance and had to trip the cable's breaker. Instead, a worker tripped the main breaker that controls two 115,000-volt feeder cables that power the entire signaling system.

Sixty-thousand people were using the T at the time of the outage, between 8:50 and 9:20 Thursday morning.

Leary said he does not recall a system-wide power outage occurring in the T's 120-year history.

"I'd like to apologize to our customers, and we'll do better," Leary said.

In the 30 minutes of downtime, power was cut to the signaling system, fare boxes and station and tunnel lighting — but not to the trains, which moved slowly while being directed manually by workers with flags.

The only evacuation was at Shawmut Station, where 30 people evacuated from a train 70 feet outside the station. Leary said the third rail there had lost power because of the station's proximity to the power source at the T's South Boston power plant.

Leary said authorities discovered the outage seven minutes after it occurred, but power was not restored until 23 minutes later — the amount of time it takes for the system to power up.  T officials had given the go-ahead to start a backup generator, but by that time the main switch had already been turned back on.

At the time of the outage, 12 trains were running on the Blue Line, 14 on the Orange, 78 on the Green, and 28 on the Red.