The Difference Between a Blackout and A Brownout

We’ve all heard of blackouts, and no one wants to hear that their home is part of one. But have you ever experienced a brownout? There’s also something called rolling blackouts that are used in states like California, Michigan, and Texas. 

As our energy demands grow, so does the chance that we’ll lose that power unexpectedly. Although officials in states across the country are working to improve the electric grid and increase capacity, it’s still not quite enough to meet demand when it’s at the highest levels. 

Let’s take a closer look at brownouts, blackouts, and rolling blackouts to see what makes each one different and why they are used.

What Are Blackouts?

A blackout is a total loss of power that’s unexpected. This complete power outage can last for minutes, hours, or days. It all depends on the reason for the blackout.
A number of things can cause a blackout to occur. Some of the most common reasons for blackouts are:

• A peak in demand that pushes the grid past its limit.
• Electric lines or transformers being damaged.
• A storm that disturbs the power supply.
• Lightning strikes that hit poles and disrupt the electrical flow.
• Ice that builds up on power lines.
• Power lines underground being disturbed.
• Tree branches falling on power lines.

The good news is a blackout isn’t a common occurrence, even in areas where hot summers cause electricity use to surge. In the past, the Electric Power Research Institute estimated that the country’s power grid system is 99.9% stable when you account for weather-related events. More recently, researchers at the University of Tennessee confirmed that our overall grid system is stable. However, the researchers also found the grid is pushed almost to the limit. 

What Are Brownouts?

The biggest difference between blackouts and brownouts is that blackouts are a complete shutdown of power whereas brownouts are partial outages. Instead of the power going out completely the system capacity is reduced. The voltage is usually reduced by 10-25%.

Another distinction is that, unlike blackouts, utilities are the source of brownouts. Brownouts are on purpose and planned in advance by the utility provider in an effort to avoid a blackout. When utilities know that there could be a spike in demand that overloads the power grid they will mitigate electricity use by making it temporarily unavailable.  

The third big difference between brownouts and blackouts is that brownouts are short term. The utility knows when it will begin and when it will end. 

You can still use appliances and electronics during a brownout, but it may not be a good idea. The fluctuating voltage during a brownout could damage electronics and appliances so it’s best to unplug them. The more precise the voltage needs to be the more likely a brownout will cause damage, which means some electronics definitely shouldn’t be used. 

What Are Rolling Blackouts?

You could also experience a rolling blackout. This is a purposeful blackout that’s controlled by the local utility. Typically, there will be an advanced warning a day or so before the rolling blackout happens. Like brownouts, rolling blackouts are used to prevent the electrical grid from being overloaded during times of peak demand. 

A rolling blackout does completely shut off the power, but it’s for a limited time (usually an hour or two) and only in a small area. The utility provider will apply rolling blackouts equally so that no area is affected more than another. 

In California during wildfire season rolling blackouts are common. They help manage peak demand and are done to reduce wildfire risk. 

We can help customers get information during a brownout or blackout, but only the local utility can get the power restored. However, Spark Energy provides a variety of energy plans for a reliable, fixed-rate that makes your monthly expenses more predictable. 

Use your zip code to see what energy plans are available in your area.