National Grid said most of the homes in Woburn that lost gas service Monday had it restored by Wednesday evening.
On Monday, a surge in natural gas pressure led officials to cut off service to about 300 homes. As of 6 p.m. Wednesday, said Christine Milligan, a National Grid spokeswoman, the utility had “completed relights for over two thirds of our affected customers.”
“We expect to keep making progress through the night . . . We’re on track to have all restored tomorrow,” she said in an e-mail.
The timing “will depend on how quickly we get access to homes — as people will need to be home for us get in. For those who are not home, we will leave a door tag on their door letting them know that their home is ready to relight and providing a number for them to call. Once they call, we’ll be there promptly. (Keep in mind, we’re right here. So customers won’t need to schedule anything. Those who have a door hanger should just call us and we’ll get to them asap.)”
In addition, Mulligan said the utility has “completed a very thorough assessment of our system and have confirmed that there was no damage.”
The utility said previously that pressure rose when a worker “inadvertently introduced excess gas into a portion of our system” during routine maintenance work near Wyman and Hart streets.
The company said it immediately realized the mistake, which it attributed to “human error,” and reduced the pressure within minutes. National Grid officials said the pipeline system did not appear to be damaged but gas service was shut off “as a precaution, and to confirm that there is no damage to the system.”
No one was evacuated, and officials said the homes were safe.
As for the precise nature of the human error, Mulligan said that the utility will “shift our focus to an investigation of what happened after we’ve completed this event.”
The Woburn incident came less than a month after a series of explosions and gas-fueled fires devastated three municipalities north of Boston. Thousands of homes that are serviced by Columbia Gas of Massachusetts remain without gas in the Lawrence area.
A man was killed in the blasts, and more than 20 other people were injured.