When a wildfire starts, people often assume that it is caused by a human. While humans do cause many fires – either accidentally by throwing a cigarette butt or on purpose, as is the case in arson – sometimes there are other causes. One common cause of wildfires is power lines.
The media has reported that power lines are likely to blame for the recent North Bay fires in Santa Rosa and Sonoma County. These destructive fires started on the evening of October 8, 2017, as emergency calls started pouring into 911 call centers. Within a 90-minute period, fire crews were dispatched to 10 separate locations.
Before all of this happened, emergency dispatchers had received calls describing electrical transformer explosions and falling power lines. Wind gusts in the area were hurricane strength, peaking at 75 mph. The wind caused poles to break, damaging wires and other utility infrastructure.
Ways in Which Power Lines Cause Fires
There are several ways in which fires start from power lines:
- Downed lines. This is one of the most common causes of power line fires. Downed power lines are not “dead.” They are often energized, which means that any contact with them can cause electrical shock or fires. These downed power lines can fall onto dry land and ignite a fire. If the surrounding areas are also dry, a fire can quickly spread.
- Contact with vegetation. If a power line hits a tree or falls to ground and ignites grass or foliage, a fire can result. Fires can also start when a branch spans two conductors, causing electrical energy to burn the branch and snap the power line.
- Equipment failures. Transformers, switches and insulators often last for decades. However, circuits have thousands of components, and sometimes these components fail. When components fail, they may spark or burn combustibles, leading to fires.
- Conductor slap. While not common, conductor slap occurs when two conductors touch each other. When this happens, hot particles may fall to the ground and start a fire. Conductors are usually spaced far enough apart to prevent this from happening.
Power Line Fire Prevention Tips
To prevent another tragedy like the recent North Bay fires, the following steps can be used to reduce or eliminate power line fire risks.
- Let your utility company know if any trees or branches are interfering with power lines.
- Assume all power lines are energized, even if they are downed. Do not touch them or operate machinery near them.
- Be on the lookout for downed power lines after a storm. Immediately alert the utility company to prevent a fire. Do not attempt to touch a downed power line or to drive over it.
- If a power line does ignite a fire, do not attempt to put out the fire with water as you can make the fire worse. Warn others to stay away, call 911 and notify the utility company.