A problem with an electrical panel is being blamed for halting all service on the Expo and Millennium SkyTrain lines Monday.

TransLink communications director Colleen Brennan said the shutdown, which left thousands of riders either trapped on trains or waiting at stations, was completely unrelated to the computer card trouble that halted service on the same two lines less than a week ago.

“As far as we can tell right now, this is a completely separate incident,” Brennan said.

Monday’s shutdown is still being investigated, but Brennan said it appears an electrical panel issue caused a complete power outage.

“We were not even able to get announcements over our PA system because of that, and it brought all of our SkyTrains to a halt,” she said.

The Canada Line connecting Vancouver and Richmond wasn’t affected.

The disruption started during the noon hour, stopping all trains on the tracks, and the system stayed completely offline for more than three hours.

Limited service on the Millennium Line between VCC and Sapperton stations resumed around 4 p.m. and TransLink confirmed service was fully restored around 5:30 p.m.

“Thank you for your patience and sorry for the inconvenience,” the transit provider posted on Twitter.

Countless frustrated riders used the same social media site to vent their frustrations. Even Vancouver Mayor Gregor Robertson chimed in, calling the repeated issues “unacceptable.”

“Transit system needs stable funding + local accountability!” Robertson wrote.

The Ministry of Transportation declined to speak to the issue Monday, calling it an operational problem that TransLink is best suited to address.

Shortly after the outage was discovered, TransLink sent staff onto guideways to open up trains and let passengers walk to the nearest stations. A few riders went rogue before staff could arrive, forcing doors open and exiting the trains alone despite warnings that similar behaviour exacerbated the problem during the last outage.

TransLink confirmed everyone trapped on trains had been let out by 3:45 p.m.

Vancouver police also announced they had temporarily suspended taxi enforcement to help stranded commuters get home. All taxis normally barred from working in Vancouver were allowed to pick up fares in the city.

Last Thursday, a computer problem halted the same lines for almost an hour before limited service resumed. It took another two hours after that for the system to be fully restored.

TransLink set up bus bridges between SkyTrain stations but there were massive crowds of passengers for much of the evening.

A backup computer system that would help in the event of a breakdown would cost $20 million, according to TransLink executive Fred Cummings.