How Do Electricity Blackouts Occur?

Weather and Natural Disasters

• Most power outages are caused by weather and natural disasters. Lightning causes power outages when it directly strikes electrical equipment or when it strikes trees that may fall onto power lines. In severe cold weather, ice can build up on power lines and on trees, for the weight of the ice on the trees' limbs could make them fall onto electrical infrastructure. Flooding and water exposure during rainstorms and snowstorms can damage electrical equipment both above and under the ground, leading to power failure. In areas prone to dampness and excessive moisture, measures must be taken to seal and protect electrical equipment. Electrical circuits exposed to dust and sandstorms are also at risk for frequent power failures if not properly protected. Destruction caused by the power and force of severe natural disasters such as tsunamis, earthquakes, tornadoes and hurricanes can leave an area without electricity for months.

Animals

• Sometimes small animals can cause power outages when they climb on electrical equipment. When they climb on parts such as transformers and fuses, these pieces of equipment shut down to protect the rest of the electrical system.

Short Circuits

• Short circuits can cause not only power failures but fires and explosion. A short circuit happens when electrical current travels along a path that is different from the intended one. This can happen when the insulation of wires breaks down, when a conducting material like water is accidentally introduced to the system, or when electric motors are jammed. The excess of electrical current can cause damage to equipment as well as fire and explosion in more severe cases.

Power Surges

• A power surge happens when electrical current flow to a spot increases excessively and disrupts a steady current flow. This can happen when lightning strikes electrical equipment or when electrical devices that demand a lot of power -- such as elevators and refrigerators --- operate. Power surges can lead to overheating and destruction of equipment.

Human Error

• Human error that causes electricity blackouts most often occurs in vehicle and construction accidents in which power lines are broken or contact is made with electrical equipment.

Utility Companies

• Some electricity blackouts are due to errors by the utility operators themselves or the equipment they supply. Sometimes the equipment used by an electrical utility company is faulty, defective, or needs to be replaced.