Can You Tell a Brownout From a Blackout?

Most of us are painfully aware that power outages are becoming more frequent in the U.S. The No. 1 cause is extreme weather (more on that later), but there are a variety of other causes.

What some of us may not be aware of is that the length of these blackouts is increasing. Dramatically so.

The length of power outages in America has increased from approximately 3.5 hours to more than 7 hours. That’s over a recent eight-year period. According to the Energy Information Administration.

That’s a significant increase. Especially when you consider it’s not safe to eat food kept in a refrigerator without power for four or more hours.

When blackouts become likely, government officials tell people to reduce electricity consumption. Turn down the heat when it’s freezing cold? That’s easy for them to say.  

Blackouts Usually Come Without Warning

What about brownouts? Are they any easier to deal with than blackouts? And what’s the difference between the two? Let’s take a look.

A blackout is a complete interruption of electrical power in a certain service area. Sometimes they are confined to small areas. But often they are much more widespread.

They almost always come without warning. And it’s difficult or impossible to know how long they will last. Power utilities sometimes provide estimates regarding how long they will last. But that’s all they are – estimates.

As mentioned, blackouts are caused by a large number of factors. Including severe weather and peak power demands.

Brownouts Are Normally Planned

A brownout is very different from a blackout, but can still cause plenty of problems. Brownouts are partial, temporary reductions in system voltage or total system capacity.

The word “brownout” refers to lights dimming when the voltage sags. Rather than turning off altogether.

Brownouts can be unintentional. But often they are an intentional drop in voltage in an electrical power supply system.

In an emergency, power utilities will use a brownout to reduce the load in order to avoid a blackout. Or even a total collapse of the system. Brownouts usually last only minutes to an hour or so.

Different Electrical Devices React Differently

Now, we can tell ourselves that brownouts are better than blackouts. After all, we’d rather have dim light than no light at all.

But the fact that brownouts occur at all? That’s another example of how our aging and vulnerable electrical grids are failing us.

A typical brownout will reduce the system voltage by approximately 10 to 25%. And usually for a short period of time. Different electrical devices will react differently to this type of sag in power.

Take heat and lighting systems, for example. They can function well on suboptimal voltage for short periods of time. But sensitive electrical equipment requiring more precise voltages could malfunction. Including computer disk drives.

What About Rolling Blackouts

Earlier I mentioned that blackouts “almost always” come without warning. An exception is rolling blackouts.

These are full outages, planned for a specific and usually short period of time. They’re designed to prevent the system from overloading. Which would cause a much longer blackout.

Utility officials will generally issue warnings prior to implementing a rolling blackout. This allows customers to use electrical appliances prior to the rolling blackout.

And so that customers can ensure they have fully charged backup power banks. Which will  assist with whatever electrical needs they have during a rolling blackout.  

Weather & Vehicles Can Cause Outages

What are the most common causes of power outages in the U.S.? You can guess most of them.

Not surprisingly, severe weather represents the No. 1 cause. Such as rainstorms, blizzards, ice, and wind. Lightning figures into the mix as well.

Another cause is trees coming into contact with power lines. High winds can break off branches. But sometimes older trees collapse, resulting in the same problem.

Vehicles involved in accidents can also cause power outages. Generally when they collide with a utility pole or power station.

Animals, Excavation, & Earthquakes Also Contribute

Sometimes our small, furry friends get too curious about electrical wires. And where they lead. This can cause short circuits. It doesn’t end well for the animals either.

On occasion, excavation digging disturbs underground cables. Check with city officials before doing any digging on your property.

Here’s another one related to weather. Both extreme cold and heat result in high power demand. And that can prove to be too much for electric cables. As well as transformers and other electric equipment.

Finally, even though they are rare, let’s not forget earthquakes. Even “small” quakes can damage electrical facilities and power lines.

Outages Are Inevitable; Peace of Mind Is Possible

Unintentional blackouts and brownouts. Intentional blackouts and brownouts. At the end of the day, they mean basically the same thing.

It’s an interruption in our lives that we would like to live without. It means little or no light. Little or no heat or air conditioning. Food spoiling. Computers failing. Phones going dead.

And for some people, essential medicines going bad. Or medical equipment failing to operate.

Sorry for the doom and gloom here, but it’s reality. Fortunately, there’s another reality: backup electrical power is available. Prepare for the inevitable and gain the peace of mind you deserve.


  • Mike Peters - February 21, 2024

    My wife and I have been prepping for many years. In the 70’s it was the cold war, in the 90’s it was y2k. Since then its been one conflict after another. We purchased multi fuel generators, food, all the essentials we thought we may need. But over time you realize you may need something more, like longer term storage foods or power when you can’t get fresh fuel or propane. The 2000x generator has given me peace of mind. The freeze dried food kits from 4P has insured us of having long term food for my extended family. As time goes on I am sure there will be improvements for preparing, and am confident 4Patriots will be there to provide them. Thank you for an excellent company and your continued support of our veterans.

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