Power Outages: 8 Typical Triggers
Power outages occur for a variety of reasons, but weather is the one of the most frequent causes. Specifics differ based on climate, but experts estimate between 40% and 70% of all outages are directly or indirectly associated with weather. Let’s look at eight typical factors that trigger power outages:
- Lightning causes close to one-third of all outages. When it strikes a power line or transformer, it can temporarily disrupt power transmission and cause flickering lights and power surges. If the wiring and components are damaged, it trips a breaker that stops electricity flow to prevent safety hazards and additional damage.
- High winds, on their own or in conjunction with derechos, hurricanes and tornadoes, cause both direct and indirect damage: They can blow down power lines and poles, cause lines to swing into each other creating an electrical fault, or topple trees that then fall onto power lines causing faults, breakage and downed lines.
- Ice storms create icy buildups on power lines, and the sheer weight can pull down lines. More often, however, the weight of ice causes limbs or trees to fall onto power lines, bringing down lines, poles or both.
- Rain, snow melt and flooding put power lines and equipment at risk. Moisture can penetrate deteriorated sheathing and cause shorts in power lines, and standing water can damage both aboveground and buried distribution equipment and lines.
- Trees cause significant damage to power lines. Up to two-thirds of storm related damage is attributed to trees, and aging or deteriorating trees can at any time fall or drop branches that break or tear down power lines.
- Animals cause up to 20% of outages. Birds, raccoons, squirrels and snakes enter transformer boxes seeking warmth, food or shelter, come into contact with live wires, bid the world adieu and cause an outage. Squirrels occasionally gnaw through power line sheathing, causing a short circuit and an outage.
- Human actions, from car crashes and accidental damage to vandalism and physical attacks, also create outages. Car crashes and accidents account for 8% to 10% of outages, and a quick scan of several power outage databases indicates a surprising number are caused by people who physically damage power equipment, usually at distribution points.
- System overloads due to heavy air conditioning use in extremely hot weather or furnace and heater use during cold weather cause high electrical demand throughout a service area. This can overtax the system and lead to outages.
Up to 90% of power outages are highly localized, affecting people in a specific community or defined geographic region. Roughly 10%, however, are associated with power generation, equipment issues or transmission problems, which tends to affect significantly more people over larger regions of the country.