About 100 National Grid employees in Massachusetts are now living at work during the coronavirus state of emergency.The employees impacted are behind the controls that protect the integrity of the power grid, and they are considered essential under the state's guidelines.Phillip Lavallee, the director of the company's New England Transmission Control Center, said the crew is responsible for making sure all the National Grid transmission lines are functional and that all substations are operating at 100%.National Grid initially asked for volunteers to stay at work to man the control rooms, but with the rapid spread of COVID-19, the company decided to sequester those control room employees. "Really, what we didn't didn't want to have happen is have some of our employees become sick," Lavallee said. "We have limited resources in our control rooms with qualified operators, and we really felt it was necessary to be proactive."Lavallee is used to having all hands on deck when powerful storms hit, but he says it is the first time he can remember not being able to go home after working.National Grid started sequestering the employees about one week ago. Lavallee says morale is good and he credits his staff's commitment to the community it serves.The employees who are currently sequestered at work will be relieved in a couple of weeks by other National Grid employees who have been voluntarily quarantining at home.