It also recommended the company improve the way it monitors the feeder cables.
Each feeder cable is tapped at several locations with transformers, which draw off power and step it down again.
Con Ed cut service when problems developed with 3 of the 28 feeder cables that carry electricity to the area.
"Who made the decision that only 14 feeder cables should service Washington Heights?"
On July 2, before the previous blackout, 13 feeder cables were down.
Each feeder cable has hundreds of parts, which are gradually replaced as they wear out.
But by midnight, one of the feeder cables was back in service, and the Mayor was saying that things could have been worse.
In the days since the blackouts began, he said, all but one of the 10 major feeder cables that went down have been repaired.
Two 350-metre-long feeder cables isolated by compressed air go from the station building to each of the antennas.
When the power failed, several large feeder cables from the reactor were put out of commission.