What is a Brownout?

Mary McMahon
Mary McMahon

A brownout is a temporary interruption of power service in which the electric power is reduced, rather than being cut as is the case with a blackout. Lights may flicker and dim, and the event also often wreaks havoc with electrical appliances such as computers. This could be considered the opposite of a power surge, an electrical event in which a sudden burst of power enters the system.

A brownout, during which power service is interrupted and reduced, may cause lights to flicker and may damage computers and other appliances.
A brownout, during which power service is interrupted and reduced, may cause lights to flicker and may damage computers and other appliances.

There are a wide ranges of causes for brownouts. Just like blackouts, overloads on the electrical system can trigger one, as the generating facility is unable to provide enough power. It can also occur when events such as storms disrupt the distribution grid, or when there are other problems in the system. They can last for a few seconds or a few hours, depending on the cause and how quickly a power utility can get full power running again.

If just one home is experiencing power problems it is likely a service problem rather than a brownout.
If just one home is experiencing power problems it is likely a service problem rather than a brownout.

In some cases, a brownout is actually deliberate, in which case it is known as a voltage reduction. Voltage reductions are undertaken when utilities sense that a disruption in the grid may lead to serious problems. Rather than instituting rolling blackouts, the utility may temporarily cut voltage to some customers in an attempt to stabilize the grid and to allow reserves of power to accumulate again.

During a brownout, customers should turn off appliances like computers, as the irregular power supply can damage them. It is also a good idea to turn off lights, leaving one on to alert the customer to the restoration of full power. He or she may also want to check with the neighbors; if a single house is the only one out, there may be a problem with the power supply in that residence, and the owner should take a look at his or her circuit breakers. The resident may have inadvertently caused a problem by overloading the home's capacity to carry power, for example.

If a single house is not the only one affected, individuals can call their power company for information. If information is not available, the caller can report it to the utility, as they may not be aware of the problem. Rapid reporting can help the utility fix the problem quickly. When a brownout occurs during hot weather, homeowners should make sure to keep their refrigerators closed and keep themselves cool; people who are susceptible to heat, such as the elderly, should consider seeking out an air conditioned location to wait out the power issues.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a EasyTechJunkie researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


We had a brownout recently in a thunderstorm, which was the first time I've ever seen one. I read somewhere that lights usually fare OK but electronics don't, so I unplugged my larger things. Alas, three of four bulbs in one of my fixtures are screwed up. Two glow purple-orange, and another is dead, even though I just put it in not two weeks ago. Crazy.


Where are brownouts most likely to occur? Also is it just a USA problem?

I've never seen a brownout. Either the power is fully out or it's on.


Having a brownout during a severe thunderstorm can be scary. It adds to the anticipation of what might be about to happen.

I'm usually watching the local TV station for weather alerts during storms, and when the power starts to fade, the TV shuts down in a very ominous way. I get scared that the worst is about to hit.

Sometimes, it's just a matter of a tree lying on a power line somewhere. It can take awhile for the electric company workers to find the source of the problem and fix it, especially if there is lightning in the area that makes it too dangerous to work on the power lines at the moment.

If the brownout happens during a storm, it usually turns into a full blackout in a few minutes. The power will flicker off and on at first, but eventually, it will go totally off, and I'm left with only my weather radio to alert me to tornado warnings.


@StarJo – The easiest way to protect your appliances is to turn off the main breaker. This should be a big lever in your circuit board.

You know it has to be hard on things like refrigerators and air conditioners to run on almost no power. They create a disturbing, low buzzing sound that seems to suggest they are about to fizzle out.

Every time a brownout lasts more than one minute, I cut off my main breaker. I turn it back on every hour to see if the power has been restored fully, and if it hasn't, I turn it right back off.


What's the best course of action to take during a brownout? I don't want any of my appliances to be destroyed. Should I unplug every single one?


I had never experienced a brownout until I moved out in the country. Before, if I lost power, I lost it all the way. Now, I sometimes go through those flickering phases.

Sometimes, I suspect that the electric company is trying to work on the grid. This is because the brownout will occur when there is not a cloud in the sky.


I have been experiencing weird electrical changes. I am suspicious that a neighbor is in on this. They are experiencing financial problems and live in a $800,000 home. How can I alleviate this suspicion?


@FastPaced: You more than likely have an open neutral at the main. Call your power company to come check it out.


I lost my $1,400 compressor from a brownout. I looked all over and found the delay on break type parts are available but need to be installed on every AC motor by a qualified electrician familiar with these timers.

I decided to build my own 115v delay on a break black box that I can plug into the wall, then plug my freezer and also my fridge into it at the same time. This unit has an adjustment for working voltage and delay after break time.

The ICM491 brain relay output was only 6 amps of power so I ran that to a 20 amp relay for my two appliances. I made three of these for about $750 apiece. I offered them to my community for cost, but nobody thought they needed one. I like having my refrigeration shut off automatically when it's 10 percent low, then come back on only when the voltage is safe. --Lyle H., CA


Most articles on "Brown Out" fail to mention how this situation can affect devices that use electric motors. We live in the mountains and rely on a well for water. It uses a large motor to pump the water to a pressure tank.

I have been told that if the motor is running or comes on during a brown out the low power supply could "burn out the motor." This can be an expensive repair, plus you would have no water until it is replaced. It can also affect refrigerators and freezers.

Electronics and computers are always mentioned in the articles, but not large motors that draw a lot of current.


Brownouts can be particularly harmful to systems with digital control circuits because the sag in voltage causes the system to behave erratically.


This is also sometimes referred to as a "sag."


In my home, every single time I run my dishwasher, washing machine, and my hair dryer I experience a brownout.

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