# Utility-caused wildfires

Utility-caused wildfires are a subset of human-caused wildfires that are directly ignited by utilities, usually power lines. They are unplanned ignitions that can cause wild burns. Hotter and drier weather as a result of climate change has been liked to lower moisture content in vegetation, which, along with high tree mortality has created ideal wildfire conditions. Ignition often occurs when power lines come in contact with vegetation, whether elevated or on the ground.
Industry critics claim that the industry is not doing enough to mitigate these disasters.

## Examples

Throughout the world, utilities, especially overhead power lines, have caused wildfires. In 2023, downed power lines sparked fires in Lahaina, Hawaii. In February 2024, on the Texas Panhandle, a decayed utility pole fell on dry grass and sparked the largest wildfire in state history. The 2018 Camp Fire, the deadliest and most destructive wildfire in California state history, was caused by a single faulty hook on a PG&E transmission line. In the notorious 2009 'Black Saturday' fires in Victoria, Australia fires sparked by power lines killed 159 people and caused more than $4 billion (AUS) dollars in damages. In Greece, on August 11th 2024, a wooden electricity pillar with a loose cable held with a clothes hanger, sparked a fire that killed one woman and burned over 10,000 hectares.

## Causes

Utility-cased wildfires can be started by a variety of factors.

### Downed lines

The vast majority of transmission lines, over 70%, in the United States are outdated, and are near 25 years old. The average age for power transformers that power over 90% of the country is 40 years old. Power lines, whether old or new, are susceptible to storm damage, and, in 30% of cases, the power line does not automatically shut off. This can happen when the fallen line draws too little electric current to activate a fuse or circuit breaker. These high-impedance faults (HiZ) can cause high-energy, high-temperature arcing that can cause ignition.

### Contact with vegetation and foreign objects

Vegetation contact, and contact with foreign objects, such as trees, are leading causes of wildfires. In California, these factors were responsible for 35%, and 18%, respectively, of utility-related fires larger than 10 acres. Strong winds have been known to exacerbate these problems. Live wires can ignite dry vegetation and fuels, and fallen trees can result in downed lines.

### Conductor slap

Power lines are traditionally designed with significant clearance between conductors, this prevents them from contacting under normal operating conditions. Under poor conditions, line conductors can slap against one another; this causes high energy arcing, and, occasionally, small bits of molten metal (generally aluminum) are ejected. These ejected pieces of molten aluminum can ignite wildfires.

### Component failure

Many components, such as switches, transformers and insulators, contain thousands of complex circuits and parts. While often able to effectively provide service for decades, they do eventually fail. Occasionally, before complete failures, there is electric arcing and sparks that are too small to be detected by fail-safe sensors. These sparks and electric arcs can result in the ignition of vegetation or foreign objects.

## Solutions

Electric companies are investigating solutions such as burying power lines, installing sensors, and using software to monitor cables and automatically shut them off. In 2023 wildfire mitigation plans, Californian utility companies proposed over $9 billion to mitigate factors that cause wildfires.