Significant delays on the T during the Friday evening rush hour were the result of a faulty power cable, MBTA officials said.

At a Monday meeting of the MBTA’s Fiscal Management and Control Board, officials said a power cable near Causeway Street in Boston’s North End failed Friday afternoon, creating signal problems across the system just as commuters headed home for the weekend. MBTA General Manager Steve Poftak described it as a “challenging evening commute.”

“The timing of this particular incident really couldn’t have been worse,” MBTA Deputy General Manager Jeff Gonneville said.

Trains on the Orange, Blue and Green Lines experienced severe delays, some as long as 30 minutes, on Friday afternoon and evening. Because the electronic system was down, employees posted at each station had to signal manually to one another to keep trains running safely.

Normal service was restored around 8 p.m., but the headaches – just three days after the New England Patriots victory parade created unrelated delays – prompted leaders to say they were taking additional action.

Emergency repairs are ongoing, and Poftak said the MBTA granted additional resources to an ongoing study of the system’s power infrastructure, setting a new goal to complete it by the summer, and accelerated implementation of a $170 million contract to upgrade power systems.

“It’s not an ideal situation for us,” Poftak said. “We know folks were inconvenienced.”