Touch and Step Potential: What to Do Around a Downed Power Line

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Touch and Step Potential: What to Do Around a Downed Power Line

What To Do and Not Do Around a Downed Power Line

Everyone needs to know about touch potential and step potential. What would you do if you came across power lines lying on the ground? What if you’re in a car accident and knock power lines onto your car? Whether you’re in the car or you are a bystander, you need the right information to make it back home safely. 

Thank you to Puget Sound Energy for making this electrical safety video. 

Forward to your friends or post on social media. You could help save a life.

 

Touch Potential and Step Potential Explained

Touch potential, as the video explains, is the potential of getting an electric shock when you touch an energized object with one part of your body and another energized or grounded object (metal structure, concrete, or the earth) at the same time.

Step potential means a person potentially can get an electrical shock when he or she takes a step or stands on the ground with voltage between each foot

For example, this can happen in a situation where a power line is lying on the ground (or on your car) and the power line is still energized. The closer one gets to the power line, the more the voltage increases between steps. That’s because electricity from the broken line is spreading all around the area the line is touching, creating different voltage “shells” in the earth’s surface. If you step across one of these “shells,” you could potentially encounter a voltage shell with enough voltage to cause physical harm or even death. 

What If This Happens to You?

Let’s say a person loses control of his or her vehicle and hits an electric pole, as the video shows.  The line above breaks and falls onto the vehicle. If anyone should try and get out of the car normally, one foot first and then the other, while touching the vehicle with one or both hands, electricity will then have a way to flow through the person’s body to the earth: touch potential.

Believe it or not, the best thing to do is to stay in the vehicle if there is no other danger of harm. However, if a fire starts in the vehicle as a result of the crash, then, of course, it would be necessary to leave the vehicle immediately. The next few steps are critical to follow carefully.

1. Get out of the vehicle by jumping out and landing with both feet and knees locked together.  (Not an easy thing for some – but it is important that you land with feet together at the same time so that no voltage “shells” are stepped across with the feet. If you land with feet apart, electricity will be able to flow from one foot to the other foot: step potential.)

2. Shuffle away from the vehicle, never lifting your feet off the ground. Shuffle about one-half foot at a time, alternating each foot carefully. Be careful to NOT lose your balance. If you fall and touch the ground with your hands, you create step potential by allowing electricity to flow from your feet to your hands. 

How far away should you shuffle? Best practice is to go a distance of 30-35 feet. That distance is roughly equivalent to the height of the power pole you see above ground. If you’re not confident in estimating that distance, shuffle a few more feet than what you reasonably think the pole’s height is.   

Don't Get Shocked

Touch and step potential are two hazards of downed power lines. But you can reduce your chances of getting an electrical shock by taking the right actions in an emergency – all because of the knowledge you now have. Reach out to someone else with your knowledge! Feel free to share this article and video. 

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Author

Ken Sellars

Ken Sellars is an instructor of electrical safety, NEC, Grounding/Bonding and Arc Flash Safety courses nationwide. Read more about Ken.

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