Do High-Voltage Transmission Lines Get Shut Down During Wildfires?
Every wildfire season, one common question that often arises is: Are high-voltage transmission lines shut down when wildfires occur? With fire spreading through forests and mountains, many people wonder whether the active power lines that run across these areas might cause additional risks such as electric arcs, explosions, or safety hazards for firefighters. In this post, we will explore how power supply management works during wildfires and whether high-voltage transmission lines are actually shut down when such disasters happen.
How Is Power Supply Managed During Wildfires?
The short answer is that high-voltage transmission lines can be automatically or manually shut down depending on the situation. However, not all power lines are immediately turned off whenever there is a wildfire nearby. The decision to cut power depends on several critical factors, including the proximity of the fire to the lines, heat levels, and the risk of damage to transmission equipment such as towers and insulators.
There are two main methods of shutting down power in these situations: automatic shutdown through protective relays and manual shutdown by control center decisions in cooperation with firefighting authorities.
Automatic Shutdown: Role of Protection Relays
High-voltage transmission systems are equipped with protection relays that monitor current, voltage, temperature, and arc discharges. When a wildfire causes intense heat or allows flames to approach the power lines, a flashover (electrical discharge across air) may occur. In such cases, protection relays detect the abnormal electrical conditions and automatically trip the circuit breakers to stop the power supply within seconds.
Distance relays, earth fault relays, and overcurrent relays are commonly used in high-voltage systems to detect these risks quickly and accurately, providing essential safety measures against fire-related electrical incidents.
Manual Shutdown: Coordination with Firefighting Authorities
In some cases, even if the automatic system does not trip, manual shutdown can still be carried out based on field assessments. When the wildfire spreads dangerously close to transmission lines or when firefighting personnel need to approach the area for extinguishing efforts, the power supply is manually cut off by the grid operator (such as KEPCO) in cooperation with firefighting agencies.
Especially when helicopters or ground crews are actively fighting the fire, power shutdown is crucial to prevent electric shock accidents and ensure safe working conditions for the emergency responders.
Key Factors Considered Before Shutting Down Power
- Voltage level of the transmission line: Ultra-high voltage (154kV or higher), high voltage (22.9kV), or low voltage (220V, 380V).
- Distance between the wildfire and the transmission line: How close the flames or heat are to the equipment.
- Occurrence of flashover or arc discharge: Automatically detected by relays if present.
- Damage risk to structures: Towers, insulators, or other components at risk of fire-related failure.
- Safety of firefighters and rescue workers: Power shutdown is coordinated with fire departments before entering the area.
Why Not Always Shut Down Immediately?
Ultra-high-voltage transmission lines are part of interconnected nationwide power grids. Cutting off one section of a transmission line without proper coordination could cause widespread blackouts in neighboring areas. This is why immediate shutdown is not always the first option.
Instead, the grid operator typically implements load balancing and rerouting of power before safely cutting off the affected line. This approach prevents accidental power outages and maintains overall grid stability while ensuring safety during wildfire incidents.
Real-Life Cases of Power Shutdown During Wildfires
In South Korea, during the 2022 wildfires in Gangwon and Gyeongbuk provinces, certain high-voltage distribution lines were shut down in advance after consultation between the power company and fire authorities. For ultra-high-voltage lines, the decision was based on the fire’s spread speed, direction, and the network’s structure. Some lines were shut down while others continued operating through alternative routes to maintain the grid’s balance.
This clearly shows that fire-related power shutdowns are managed through a combination of automated systems and human judgment, ensuring both safety and stable power supply management.
Summary and Conclusion
When wildfires occur, whether high-voltage transmission lines are shut down depends on multiple factors, including the severity of the fire, proximity to the lines, system design, and the safety needs of firefighting teams. Power may be cut off automatically through protective relays or manually after coordination between grid operators and fire departments.
Understanding these mechanisms helps clarify how electricity is safely managed during wildfire situations and prevents misunderstandings about power shutdown procedures. Through proper system design and cooperation between agencies, the risks of wildfire-related electrical accidents can be minimized effectively.