The day after the West Side Blackout threw New Yorkers into darkness for about five hours, officials from Con Edison said that they had no idea what caused the power outage—but repeatedly scoffed at the idea of a blown 13,000-volt cable, located at West 64th Street and West End Avenue, was at fault for throwing six networks offline. "To think a 13 KV feeder translate to the transmission system is sort of a nonstarter," Con Ed President Timothy Cawley told reporters. By Monday afternoon, the utility changed its mind, blaming the 13,000-volt cable.

In a statement, Con Ed said, "Our inspection of equipment and preliminary review of system data over the past 40 hours indicates that the relay protection system at our West 65th Street substation did not operate as designed. That system detects electrical faults and directs circuit breakers to isolate and de-energize those faults. The relay protection system is designed with redundancies to provide high levels of reliability. In this case, primary and backup relay systems did not isolate a faulted 13,000-volt distribution cable at West 64th Street and West End Avenue."

The failure of the protective relay systems ultimately resulted in isolation of the fault at the West 49th Street transmission substation, and the subsequent loss of several electrical networks, starting at 6:47 p.m.

Based on our experience with the transmission and distribution system, we initially believed the 13,000-volt cable fault was unrelated to the transmission disturbance. While the cable fault was an initiating event, the customer outages were the result of the failure of the protective relay systems.

From the moment the event began, we focused on restoring customers safely and quickly. More than half of the customers were restored in under three hours and all within five hours. Once we restored customers that evening, we immediately turned to determining the cause of the outage.

Our investigation has involved inspecting and testing transmission equipment, and analyzing the large volumes of data. Through this work, we determined that the outage was not caused by transmission equipment. Further analysis identified the issues with the relay protection system.

We have restored our system to its normal state to continue providing our customers with the high level of reliability they expect and deserve. Our analysis of data and testing of the relay protection equipment is continuing, and will provide more insight into why the system, and its multiple redundancies, did not operate as designed. We will share additional information as it becomes available.

The blackout began at 6:47 p.m. on Saturday night, affecting much of the West Side of Manhattan, from 30th Street to 72nd Street and Fifth Avenue to the Hudson River. Power was restored to all networks about five hours later, but not before the outage caused hundreds of people to be stuck in elevators; commuters to be stuck in trains; businesses of all stripes to close (bodegas handed out ice cream; Broadway and other shows were cancelled; performers sang in the street); and civilians to become traffic agents to direct vehicles and pedestrians through the chaos.

A man told WCBS 2, "I saw on the corner of 64th and West End Avenue that one of the manhole covers, there was some black smoke coming out of it, then the power went completely out and I ended up calling 911."

Con Ed spokesperson Philip O'Brien compared the electrical system to a circuit coming into the living room of a house. In an interview with WNYC, he said, "If there's a fault, the living room circuit should be tripped and sort of the fuse goes out in the living room. In this case, the whole main circuit went out, when it should have only been the one circuit to the one room."

Here are Con Ed President Cawley's exact words during Sunday's press conference:

Cawley: Yeah, so there would be theories. I can tell you that the failed circuit is a 13,000-volt feeder. They fail - we have a lot of them and they, they fail on occasion, and we have a lot of maintenance and replacement programs in place to mitigate that, to sort of identify where the most risky areas - the riskiest areas are. But really, to think a 13 KV feeder translate to the transmission system is sort of a nonstarter. Our team will look at everything, because it happened in and around the time. But it might - the reverse potentially could be true, but that being the cause of the backup to the transmission system is really a nonstarter.

He also said, "I would say, the voltage level of that feeder, 13,000 volts, versus what we experienced"—with the substation going out— "at 345,000 volts, it is incredibly unlikely that the low voltage feeder impacted the bulk power system." (See him talk about the cable at about 23 minutes and 32 minutes in the video.)

The press conference was actually held right by the manhole. Cawley said that 13,000-volt cable wasn't the cause, but the presser was there because "this is really where folks mobilized the evening as things unfolded without a better place to mobilize - it was in the grid."

Earlier on Monday, Governor Andrew Cuomo said the blackout was unacceptable and complained about the utility, "If they do not perform, they can be replaced. Con Ed almost has an attitude of the too-big-to-fail banks. This is a franchise. This is a license. This is not a God-given-right."

With additional reporting from Spencer Lee