Brownout Vs. Blackout: What’s the Difference
In the United States, an average of more than four power outages per year brings us face to face with the reality that the power supply is not always stable. When we talk about power failures, we typically encounter two technical terms: brownout (unstable voltage) and blackout (total power outage).
While these two terms are often used interchangeably, they represent very different situations. According to statistics, more than 60 percent of U.S. households have experienced at least one unstable voltage or total power outage in the past year. From an office computer suddenly shutting down to a home's air conditioner losing its cooling effect, these can all be signs of a brownout or blackout. And in this age of heavy reliance on electricity, it's become especially important to understand the difference between these two situations and how to prevent and respond to them with backup power.
What is a Blackout?
A blackout is the complete loss of electrical power to a region or area. When a blackout occurs, all electricity supply is interrupted which results in a complete shutdown of electronics and electricals. Blackouts are caused by several factors such as equipment failure, power grid issues, and severe weather events like storms or hurricanes, among others.
Blackouts often come without warning and last for unstipulated periods. But in some cases, blackouts could be pre-planned by the energy company as a precaution or to fix a fault on the line. These are called planned outages. They typically occur with some warning and have a pre-defined timeline.
There’s also what is known as rolling blackouts. Utility companies use these as a means of coping with power peak demand that the current supply can’t meet. These typically affect a specific area for a pre-defined period (usually a couple of hours) to help take the stress off the power grid.
The utility company will typically spread these out from time to time to ensure that no one area suffers more than the other. Like planned outages, a utility company will notify clients before a rolling blackout.
What is a Brownout?
A brownout is the temporary intentional or unintentional drop in voltage in an electrical power grid. Utility companies use brownouts for load reduction, especially during an emergency. These typically last a few minutes and sometimes hours. The term “brownout” is derived from the dimming of lights when the voltage drops.
In some cases, a brownout can be caused by a disruption of the electrical power grid. These are known as unintentional brownouts. But there are times when the utility company wants to reduce the load on the electrical power grid without imposing a blackout. Intentional Brownouts are common in the sweltering summers when home users turn on power-guzzling air conditioners (AC) to cool their homes.
This will in turn cause a surge in power demand on the general grid. Utility companies use brownouts to help reduce stress on the electrical power grid. The energy company will lower the voltage by 10-25% for a short time at different intervals. This is to prevent electrical service equipment like transformers from shutting down which would typically cause a blackout.
Brownouts affect different electricals and electronics in varying ways. Some will be severely affected while others won’t. Brownouts typically have minimal effect on heat and lighting because most of these can function reliably for short periods on low voltage. However, sensitive electronics like TVs, computers, and gaming consoles won’t be able to function during a brownout.
In fact, the fluctuating voltage could cause some of these to malfunction. For instance, computer disk drives are prone to failure when supplied with sustained low voltage. Electrical motors tend to heat up because they need to supply the same power as they would in a normal scenario.
However, there’s a difference between voltage fluctuations and brownouts. Depending on the area, voltage could sag by around 5% above or below the nominal range. Most manufacturers of electricals and electronics know this. That’s why most North American consumer and commercial products can safely function at voltages between 115 and 125 volts.
What are the differences between blackout and brownout?
Having understood the basic concepts of brownout and blackout, let's dive into the key differences between them. While both types of power failures can affect our daily lives, they differ significantly in their nature, scope and severity.
Brownout usually manifests itself as a planned reduction in voltage, much like dimming the lights, where equipment can still operate, but performance may be affected. In contrast, a blackout is a complete power outage that causes all power-dependent devices to stop working altogether.Here are the detailed differences between blackouts and brownouts:
Duration
Blackouts can last for a few minutes or hours depending on whether they are intentional or unintentional. Rolling blackouts and power outages are intentional and could last a few minutes or hours before power is restored. Blackouts caused by a fault on the line typically have unstipulated timelines and these are often the worst-case scenario.
Depending on the magnitude of the fault, these could take anywhere between a couple of hours to a few days before power is restored. On the other hand, a brownout is typically a couple of minutes and at worst a few hours.
Cause
Blackouts can be intentional or unintentional. Unintentional blackouts are caused by a break or fault along the power line. This could be anything such as a broken pole or malfunctioning transformer. Intentional blackouts are typically rolling blackouts or power outages and these have varying causes.
For instance, a power outage is when the utility company cuts power to an area to do maintenance work along a power line. A rolling blackout is when a utility company cuts power to an area to reduce stress on the power grid. Brownouts can also be intentional and unintentional. Unintentional brownouts can be caused by severe weather events like hurricanes or a fault along the line like a loose cable.
On the other hand, an intentional brownout is when a utility company lowers the voltage to an area to reduce the load on the power grid. The energy companies impose these as an emergency to save electrical service equipment like transformers to prevent possible blackouts.
Impact on Electronics and Electricals
During a blackout, all electronics and electricals stop working until power is restored. While blackouts are huge disruptions, they don’t usually cause any damage to electronics or electricals. Yes, in some cases computers could lose data but there are ways to protect against that (we will discuss that in the next section).
On the other hand, brownouts could cause severe damage to electronics and electricals. While lighting and low-voltage heating might not be affected, appliances like washing machines, refrigerators, TVs, fans, among others can be severely damaged by a sustained brownout. That’s because these have electrical motors which typically can’t function at low voltage.
Brownouts also damage insulation. Insulation is basically a variety of materials used to reduce the transfer of energy to the outside environment. It is used to cover electrical wires to protect humans and also protect against agents like water that could spark fires. Lastly, brownouts have also been identified to cause computer disk drives to fail. So, brownouts have a more negative impact on electronics and electricals than blackouts.
Knowing the difference between brownout and blackout makes it especially important to take the proper precautions. According to the Federal Emergency Management Agency (FEMA), more than 60 percent of U.S. households don't have a complete emergency plan for a power outage, which makes them especially vulnerable in the face of a power failure. Let's take a look at how to prepare for these two different types of power failures.
How to Prepare for a Blackout
In the event of a blackout, the first thing to do is to reach out to your utility service provider and inform them. Most of these have toll-free numbers on which you can call and let them know of your problem. Some also can be reached via WhatsApp while others have a dedicated mobile app.
Reaching out will help you determine how long it will take before power is restored. This should ease your planning phase. Also, it could speed up the restoration process especially when disruption is not the routine rolling blackout or power outage done by the energy company.
Use Alternatives for the Meantime
If you need to cook a meal, gas is the best alternative during a blackout. Most electrical ovens manufactured today have burners that use gas. For lighting, you can use flashlights and rechargeable lamps. These can give you somewhere between 5-8 hours depending on their battery capacity.
Turn to Power Backup Sources
Having a power backup source like a power station or generator is an efficient way to tackle blackouts. This way you can switch all the appliances you want to use as you wait out the blackout. There are several power stations sold on the market today. These are basically high-capacity battery packs in a compact and portable format. Most of these can power a variety of devices like TVs, computers, air conditioners, and electric grills. However, it’s worth noting that the more applications you can use for one, the steeper the price. A 256Wh power station could power a TV for 2-7 hours, depending on its capacity.
Generators are a bit different but are just as effective. Most mid-sized generators use petrol or propane to generate electricity. However, industrial backup generators use diesel. These are much stronger and can an office building run for several hours depending on the number of applications.
Use Power Alternatives like Solar PV and Battery System
For long-term power security, A solar photovoltaic (PV) and battery system is an excellent alternative. By converting sunlight into electricity and storing it in batteries via solar modules, basic power needs can be maintained even during power cuts. We recommend choosing the right backup power system for your scenario.
For home users, the Renogy 600W 12V Universal Off-Grid Solar Kit is especially recommended, a system that meets basic household electricity needs, including lighting, charging appliances and powering small household devices. Even during power outages, it will continue to provide you with clean energy as long as there is sunlight.
For frequent outdoor activities such as 4x4 off-roading, small RV camping, or boat fishing scenarios, the Renogy Core Mini Li-ion battery is a smarter choice. This compact portable power supply delivers up to 300A of current in less than 5 seconds, making it easy to power high start-up current devices such as refrigerators and microwave ovens, while its unique metal battery spacer retention system ensures stable performance over bumpy roads.
How to Prepare for a Brownout
In contrast, preparation for brownout focuses more on protecting electronic equipment. Installing a high-quality voltage regulator is the most basic protective measure, which ensures that the equipment can still operate stably when the voltage fluctuates. For sensitive equipment such as computers and servers, it is recommended to equip a UPS with a voltage regulator that automatically switches to battery-powered mode when the voltage is unstable.
In addition, it is also important to develop good power habits: when you know that brownout may occur, take the initiative to turn off or unplug unnecessary high-power electrical appliances, and set the air conditioning to a higher temperature, which not only protects the equipment, but also helps to reduce the burden on the power grid. In office environments, consider enabling energy-saving modes on laptops and saving important documents in a timely manner to prevent data loss due to voltage fluctuations.
Final Thoughts
Regardless of whether it’s a brownout or blackout, power disruptions can be a party pooper. Hopefully, our article has given you enough insight on how to tell the two apart and how to prepare for each scenario. Following these few guidelines will help protect your appliances and will also help you navigate the challenges that blackouts and brownouts bring.
Brownouts Vs. Blackouts FAQs
1. How long do blackouts typically last, and how should I prepare?
Typical blackouts last around 4 hours, though they can extend for days depending on the cause. Essential preparation includes storing drinking water (1 gallon per person daily), non-perishable food, flashlights, backup batteries, and a reliable power backup solution like solar kits for homes or portable power stations for outdoor scenarios.
2. How can I tell if I'm experiencing a brownout or a blackout?
The key difference lies in the power availability. During a blackout, all electrical devices stop working completely due to total power loss. In contrast, a brownout is characterized by dimming lights and reduced performance of appliances while still functioning. An effective way to confirm is using a voltage meter - brownouts show reduced voltage (10-25% below normal), while blackouts register zero voltage.
3. Can brownouts damage my appliances?
Brownouts pose a significant risk to electrical devices, particularly those with motors or sensitive electronics. During low voltage conditions, appliances draw more current to maintain operation, potentially leading to overheating and damage. That's why it's crucial to either power down sensitive equipment or protect them with voltage regulators during brownout events.
