What is the first priority at an incident involving downed high voltage power lines?

In incidents involving downed high voltage power lines, contacting the electrical company to shut off power is the first priority due to the immediate life-threatening hazard that live electrical lines present. High voltage power lines can pose a significant risk of electrocution to both the responders and any bystanders in the vicinity. When power lines are down, they can continue to transmit electricity, creating an unpredictable and dangerous environment.

By contacting the electrical company, responders ensure that trained personnel can safely secure the area and de-energize the lines, reducing the risk of accidents and allowing other actions to be taken without endangering lives. This crucial step helps to establish a safer operational environment before any evacuation, rescue operations, or perimeter establishment can be effectively executed.

The other choices, while important actions to take in managing the incident, are secondary to ensuring that the immediate electrical hazard is dealt with first. Establishing a perimeter or beginning evacuation measures cannot be conducted safely until the power is turned off, and initiating rescue operations in the presence of live electricity can escalate the danger. Thus, prioritizing communication with the electrical company is critical to ensure safety for everyone involved.