WASHINGTON — The electric grid, as government and private experts describe it, is the glass jaw of American industry. If an adversary lands a knockout blow, they fear, it could black out vast areas of the continent for weeks; interrupt supplies of water, gasoline, diesel fuel and fresh food; shut down communications; and create disruptions of a scale that was only hinted at by Hurricane Sandy and the attacks of Sept. 11.

This is why thousands of utility workers, business executives, National Guard officers, F.B.I. antiterrorism experts and officials from government agencies in the United States, Canada and Mexico are preparing for an emergency drill in November that will simulate physical attacks and cyberattacks that could take down large sections of the power grid.

They will practice for a crisis unlike anything the real grid has ever seen, and more than 150 companies and organizations have signed up to participate.

“This is different from a hurricane that hits X, Y and Z counties in the Southeast and they have a loss of power for three or four days,” said the official in charge of the drill, Brian M. Harrell of the North American Electric Reliability Corporation, known as NERC. “We really want to go beyond that.”