Basics of Blackouts

How do blackouts occur?

When the power grid breaks down due to an overwhelming power demand, a blackout can occur. The power grid is a network of power plants that collectively produce enough power to meet demand. If one plant suddenly quits producing power (lightning strike, downed power line or mechanical failure), the other plants on the network increase their output to make up the difference. If the power plants are already working near their maximum output, they will automatically shut down rather than exceed their maximum threshold. As plants shut down, they place the burden on remaining plants, which in turn also shut down. This system failure can cause blackouts that can last a few hours or days.

The loss of power and damage associated with fluctuations in the power grid do not always coincide with inclement weather. Power spikes and surges can happen when least expected, quickly and without anyone noticing.

Blackouts can knock out traffic lights, stop subway systems and shut down airports. Telephone systems crash and any electronic banking ceases.