Have you ever wondered what causes power outages? When the power goes out, it can affect your home, a few blocks around you, whole neighborhoods or even an entire city. A random power outage can happen without warning and can last for hours or days.
Why do power outages happen? Knowing the causes of power blackouts may help you be ready in advance. It’s important to be prepared. Here, we explore the various reasons for power outages and how they affect you and your community.
What causes a power outage?
1. Severe weather and storms
The biggest cause of power outages is weather. In fact, 83% of power outages are weather related.
Severe weather can take several forms:
- Wind, such as derechos, hurricanes and tornadoes, can blow down power lines.
- Lightning can knock down trees that fall on transmission wires. It can also directly hit any part of the electrical grid, including power lines and substations. If lightning is close enough, it could fry your home’s electrical system.
- Heavy rains can cause flooding and mudslides that bring down wires and short circuit power systems in homes or neighborhoods.
- Winter storms bring ice and snow that can overburden trees and sometimes elements of the grid itself, potentially damaging wires and transformers.
- Heat waves may strain components and systems. Coinciding wildfires can destroy wide swaths of land and the electricity infrastructure with it.
What is the most common cause of power outages? According to the Congressional Research Service:
- 14.8% are caused by wind and rain
- 11.5% are caused by lightning
- 5.5% are caused by other cold weather
- 5% are caused by ice storms
- 4.2% are caused by hurricanes and tropical storms
- 2.8% are caused by tornadoes
Climate Central adds that 5% of outages are due to extreme heat and wildfires.
Other causes of power outages include natural disasters such as earthquakes, tidal waves, volcanic eruptions and solar storms that knock down transmission lines, damage transformers, destroy substations and overburden components.
2. Trees
While trees breathe in carbon dioxide and breathe out oxygen, adding beauty and life to the landscape, they can also cause power outages.
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 bring down branches and entire trees onto utility poles and wires.
An individual or professional seeking to trim branches or cut down a tree may inadvertently hit a powerline and cause a power blackout.
When an old or diseased tree topples over, it can cause a power outage.
3. Animals and wildlife
When it comes to what causes power outages, look no further than local wildlife. In fact, they are the second most frequent cause for power outages. While foraging for food and nesting materials, defecating or taking shelter in the warm hum of an electric grid component, these creatures can cause damage that stops the flow of power.
Squirrels account for most of the outages. Other rodents, like rats and mice, can chew through wires in your home and throughout the power grid. Birds, raccoons, snakes and insects can also wreak havoc as major reasons for power outages.
A tongue-in-cheek site tracked "cyber squirrel operations" measuring global wildlife “attacks” on the grid, including a tote board that had squirrels in the lead followed by birds and snakes. It even mentioned monkeys and jellyfish.
4. Motor vehicle accidents
Motor vehicle accidents are a cause of why power outages happen.
A car or truck that skids out of control and hits a utility pole may bring down power lines and equipment. Driver impairment, a momentary lapse of attention or a patch of slippery pavement is all it takes.
5. Power equipment failure
Like any kind of equipment, the components that bring power to customers can be faulty or may break or wear out with age and exposure to the elements. Transformers fail, insulators corrode, insulation on cables cracks and wires snap.
Power distribution requires complex equipment that can stop working properly in any number of ways, leading to power failure.
6. High energy demand
What can cause a power outage on a clear day? An uncommon cause of a power blackout is 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. People using construction equipment can knock down utility poles. Excavators and landscapers can accidentally cut underground lines.
Considering how often power outages occur because of these kinds of mishaps, many utility companies have created hotlines that you can call to check the location of underground power lines 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 can cause power outages. People have been known to take down the power simply by 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 cyberattacks
A less common reason why power outages happen is a deliberate attempt by a foreign power or terrorist group to disrupt operations. Power suppliers have extensive security measures in place to safeguard power systems, so these types of attacks are rarely successful.
10. Planned power outages
Why did the electricity go out? It could be a planned outage. Your utility company may have reasons for power outages, like the need to conduct routine maintenance, repairs or upgrades. How often power outages of this kind occur can vary with the age and configuration of the system.
Your utility won’t leave you wondering why the electricity isn’t working, though. They do their best to give you advance warning.
What are the different types of power outages?
There are four 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.
- Rolling blackouts. A systematic and temporary interruption of electrical service done by design is a way that utility companies can relieve the stress on a power grid that is experiencing exceptional high demand, interruptions in supply or infrastructure issues. Rather than let the grid fail in unpredictable and potentially highly damaging ways, planned temporary blackouts help balance supply and demand until stability can be restored.
How power outages can affect communities
