The Difference Between Blackouts and Brownouts

With temperatures and humidity levels soaring across the country, many people are cranking up their air conditioning. And while that’s completely understandable, doing so could result in a brownout. Meanwhile, strong summer storms have also become a regular fixture...

Koichiko Koichiko
Jun 19, 2022 - 21:02
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The Difference Between Blackouts and Brownouts

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Photo: FranciscoDania (Shutterstock)

With temperatures and humidity levels soaring across the country, many people are cranking up their air conditioning. And while that’s completely understandable, doing so could result in a brownout. Meanwhile, strong summer storms have also become a regular fixture of the season so far, causing blackouts during the sweltering weather.

Both blackouts and brownouts tend to happen more during the summer, so it’s a good idea to have an understanding of the differences between the two. Here’s what to know.

The difference between blackouts and brownouts

Blackouts and brownouts can both leave you without electricity, but there are several key differences you should know about:

Blackouts

A blackout is a total loss of electricity. While some last only for a few minutes, others can occur over hours, or even several days. Much of this depends on what caused the blackout in the first place, and how difficult it is to resolve that issue. Some common causes for blackouts include:

Damaged transformers or electric lines (resulting from storms, fallen trees, and/or accidents)Increased power demand that pushes the grid beyond its limitLightning strikes to electrical polesDisturbed underground power linesIce build-up on power lines

Brownouts

While blackouts are typically caused by situations beyond the power company’s control (like bad weather and accidents), brownouts are intentional. Brownouts happen when the demand for electricity is approaching capacity (like an entire city turning on their AC on the same day), and to prevent the grid from being overloaded, the power company limits the electricity in certain areas.

When homes in an area are part of a brownout, they still have electricity—just at much lower voltage levels than usual. So, while you may be able to turn on a lamp, it will be relatively dim.

‘Rolling’ blackouts and ‘planned outages’

Sometimes, when the power company knows that the grid will be pushed to its limit, it may opt to instate intentional “rolling” blackouts. These typically happen in multiple areas for limited amounts of time, and usually come via a last-minute announcement from the power company.

But a rolling blackout is not the same as a “planned outage.” Those tend to be scheduled much further in advance for routine maintenance.