Mission Valley Power has three different types of overhead power lines. They are transmission lines, distribution lines, and secondary or service lines. The ones that present the greatest danger to the public, when they are on or near the ground, are the transmission and distribution lines. The danger from the secondary or service lines is somewhat less, but they can still be very dangerous to anyone who is not knowledgeable about working with electricity.

The first thing that must be made clear is that no one can tell if a downed power line is energized just by looking at it. Therefore, all downed power lines must be treated as if they are energized. Do not touch or go near downed power lines. Only someone who is qualified to handle power lines should go near them, and we encourage everyone to contact MVP or the local Sheriff's Department when a downed line has been spotted. In addition, there several additional dangers from downed power lines that needed to be addressed. 

One of the big dangers is downed lines in a traffic accident. Anytime a lines comes down during a traffic accident and lands on or near a vehicle it could energize that vehicle. Touching or going near the vehicle could cause death or very serious injuries. People who are in a vehicle that have power lines touching it should stay in the vehicle until they are informed by a utility person that it is safe to leave the vehicle. Also, anyone outside the vehicle should stay away from the vehicle until they are told it is safe to approach.

Another danger from downed power lines can come in the form of a wire touching or laying on a metal building or metal fence. Again, this could energize the building or fence and kill or injure someone if they were to come in contact with it.

There can be dangers from downed telephone and cable lines when installed on power poles. A broken cable or tv line may flip up into overhead power lines which can potentially energize the broken line. They may look safe, but unless someone is trained in the dangers of this situation, unqualified persons should avoid contact with these wires.

Finally, the last thing that should be addressed is what is called step potential. This condition can be created when a downed power line is laying on the ground. The power can flow out of the line into the ground. The power then flows through the ground and can create different voltages across the surface of the ground.  A person standing in an area that has these differences will cause the power to flow through the body from one foot to the other foot. The best way to avoid this problem is to stay back from any downed power line by 25’ or more.

Below are pictures of an accident that occured on highway 93.  The accident caused the line to fall across the highway, and reduced traffic to one lane for approximately two hours.