Have you ever wondered what causes power outages? When the power goes out, it can affect anywhere from a few blocks to whole neighborhoods — or even an entire city. A random power outage can happen without warning and can last for hours or days.
It’s important to be prepared. Knowing what might cause a power outage can help you be ready in advance. Here we explore the various reasons for power outages.
1. The most common cause of power outages: severe weather
By far, the most common cause of power outages is severe weather. But there’s often more than a single cause of a power outage; you can have multiple reasons for a blackout. For instance, lightning can bring down a tree that cuts through power lines. Heavy rains can lead to floods or mudslides. Extreme heat and extreme cold can also damage components of the electricity grid.
A study found major outages caused by severe weather occur at these rates:
- 8% by wind, including hurricanes, tropical storms and tornadoes
- 3% by lightning that can zap a transformer or fry wires
- 5% from snow and ice, leading to winter power outages
Natural disasters
Weather isn’t the only natural reason for power outages. Earthquakes, wildfires, floods and mudslides can wreak havoc on systems too. Less commonly, volcanic eruptions and tidal waves can also be reasons for power outages. Major events like these can knock down transmission lines, damage transformers and destroy substations.
2. Motor vehicle accidents near power lines
Motor vehicle accidents can be a cause of power outages on a local level. A car or truck can skid out of control, hit a utility pole and bring down power lines and equipment. Driver impairment, a momentary lapse of attention or a patch of slippery pavement is all it takes to lead to disaster. This kind of random power outage usually affects a relatively small area.
3. Equipment failure
Like any kind of equipment, the components that bring power to customers can be faulty, break or wear out with age and exposure to the elements. Transformers can fail. Insulators can corrode and break. Insulation on cables can crack, and wires can snap. Power distribution requires a lot of complex equipment. It can stop working properly in any number of ways, leading to just as many causes of power failure.
4. Fallen trees
Power lines along the road and leading into your house are vulnerable to damage from falling trees and branches. High winds and the load from heavy snow or ice can cause trees to snap and bring down utility poles and wires. A random power outage can happen simply when an old or diseased tree topples over without warning.
5. Wildlife looking for a new home
Wildlife can also be a factor that causes power outages. Birds, squirrels and other small animals can chew through power lines, knock down components while foraging for food or short-circuit connections while building nests. The warmth and hum of flowing electricity also seems to attract some animals.
6. High energy demand
You might wonder: Why did the electricity go out on a perfectly nice day? A common and unexpected cause of a power blackout might be caused by too many people drawing too much power in a given area at one time. On a hot summer day when everyone’s air conditioner is working overtime, excessive demand can overload the system and lead to an outage.
7. Power line damage from construction work
Power outages occur all too often as the result of preventable accidents. What causes power outages in these cases is human error. Construction equipment can knock down utility poles. Excavators and landscapers can cut underground lines.
Considering how often power outages occur because of these kinds of mishaps, many utility companies have created hotlines so you can check before you dig. Be sure to report a power outage if it occurs. For power outage safety, keep people clear of the damaged equipment to prevent serious injury.
8. Damage from the public
Professionals aren’t the only ones whose errors cause power outages. People have been known to take down the power simply doing yard work. More sinister reasons for power outages include vandalism and deliberate acts of destruction. And thieves risk serious harm to steal wire and other components for the copper inside, selling it for scrap. The result can be a random power outage.
9. Disruption of power from foreign cyberattacks
An uncommon reason for power outages, at least in the United States, is caused by a deliberate attempt to disrupt operations by a foreign power or terrorist group. Power suppliers have extensive security measures in place to safeguard power systems so that these types of attacks are rarely successful.
10. Planned power outages
Why did the electricity go out? It could be a planned outage instead of a random power outage. Your electricity supplier may have reasons for power outages, like the need to conduct routine maintenance. How often power outages of this kind occur can vary with the age and configuration of the system.
Your provider won’t leave you wondering why the electricity isn’t working, though. They do their best to give you advance warning.
Different types of power outages
There are three main types of power outages:
- Permanent fault: Despite the name, a permanent fault isn’t actually permanent. Examples of faults are abnormal or unbalanced voltage or current, or a disruption in flow. Once the fault is cleared, power is back on. It’s called a permanent fault because it won’t fix itself or reset without someone going out to deal with the fault.
- Brownout: The difference between a brownout and a blackout is that power is temporarily reduced in a brownout, not totally cut. This type of outage can keep the grid from being overloaded and going into a full blackout. Rolling brownouts are when power is reduced section by section across the power grid.
- Blackout: When the whole system fails, a blackout occurs. This is the most severe power outage. Recovering power can be difficult, especially when power stations are tripped and knocked off the grid. These outages can last hours, days or even weeks.
How power outages can affect communities
Being prepared is key when it comes to what to do when power goes out. Although the negative effects of a power outage are hard to fully calculate, what blackouts can mean for individuals or businesses can include any of the following:
- No lights or air conditioning
- A possible interruption of water and natural gas service
- A dangerous interruption in the running of life-sustaining medical devices
- No cell phone service because cell towers are out
- Damaged electronics
- Spoiled food in your refrigerator
- Inoperable traffic signals and limited travel
- Lost revenue for your business
The United States boasts one of the most robust electrical power systems in the world. Widespread or regular outages are rare. And random power outages are more often inconveniences than hardships.
Even so, knowing what causes power outages can help you know when to prepare for them or, in some cases, possibly avoid causing them. And the more information you have, the less anxious you’ll feel if the power goes out.