Power outages, often associated with severe weather or human error, can also frequently stem from wildlife. These animal-related disruptions are a common cause of electricity loss for millions of people annually. Interactions between animals and electrical infrastructure play a significant role in the reliability of power grids.
Top Animal Culprits
Squirrels are the most frequent culprits behind power outages. Their abundance, agility, and natural curiosity lead them to interact with electrical equipment, often using power lines as elevated pathways. In 2023, squirrels were responsible for 7,196 animal-related power outages in the United States, accounting for nearly half of all such incidents. These rodents gnaw on electrical wiring and insulation to wear down their continuously growing incisors. This gnawing can damage protective layers, leading to electrical faults.
Other animals also contribute to power disruptions. Birds, particularly larger species like raptors, caused 2,506 outages in 2023. Their wide wingspans can inadvertently bridge energized components, creating short circuits. Their nesting habits on power structures can also lead to issues, especially if nests contain conductive materials. Raccoons, known for their climbing abilities, can access substations and cause outages by making contact with energized parts. For instance, a raccoon recently caused an outage affecting over 2,500 residents in Connecticut.
Snakes are another cause of outages, often attracted to the warmth of electrical equipment, particularly in substations. They can climb poles and slither into tight spaces, inadvertently bridging electrical connections and causing short circuits. In 2024, a single snake caused a power outage for over 11,700 residents in Virginia after contacting a transformer. Other rodents, such as rats and mice, contribute to outages by chewing through wiring and insulation, especially when they gain entry into substations or other electrical enclosures.
Mechanisms of Disruption
Animals primarily cause power outages through short circuits, which occur when their bodies inadvertently bridge two energized electrical components or connect an energized component to the ground. When an animal’s body acts as a conductor, it creates an unintended pathway for electricity, leading to a sudden surge of current. This surge triggers protective devices like circuit breakers to open, shutting down power to prevent damage to the electrical system and mitigate fire risks.
Chewing is another common mechanism, particularly by rodents whose teeth continuously grow. These animals gnaw on electrical wires and insulation, exposing the conductive materials beneath. Damaged insulation can lead to direct contact between wires, causing short circuits, overheating, and potentially fires within the electrical infrastructure.
Nesting activities, especially by birds, contribute to disruptions when nests are built on or within electrical equipment. Nests can accumulate debris, including conductive materials, which may bridge live parts and cause electrical faults. Bird droppings, particularly from larger birds, are semi-liquid and conductive; their accumulation on insulators can lead to flashovers, creating an electrical arc and an outage. Animals can also dislodge equipment or large birds can collide with power lines during flight.
Preventing Animal-Caused Outages
Utility companies employ various strategies to mitigate animal-related power outages and enhance grid reliability. A widespread approach involves installing physical barriers and protective covers on electrical equipment. These “critter guards” are designed to prevent animals from making contact with energized components or bridging electrical connections. Many of these guards are made from durable, insulating materials and are shaped to deter climbing or perching.
Vegetation management is another preventative measure. Trimming trees and clearing brush around power lines reduces the pathways animals can use to access electrical infrastructure. By maintaining clear zones, utilities minimize opportunities for squirrels to use branches as bridges to power lines or for other animals to climb poles from overgrown vegetation.
Utility providers also use non-lethal deterrents to keep animals away from sensitive areas. While less common than physical barriers, methods such as ultrasonic devices or visual deterrents may be deployed to discourage animal presence. Ongoing equipment upgrades and regular maintenance also play a role in reducing the grid’s vulnerability to animal interference.