Step & Touch Potential

Let’s see, What is step and touch potential?

It can be understood with two basic principles of electricity.

As we know, 

1. Current flows from high potential to low potential. 

2. Also current flows through the least resistance path.

With these two basic concepts, Step potential & Touch potential can be understood very easily.

Let’s take an example. Consider the current-carrying conductor is broken and touches the ground.

In such conditions, the potential of the ground at the point where the broken conductor touches increases and decreases with distance from the touchpoint. Hence we can see that the potential near touchpoint is higher and lower at distant points. We can say that invisible rings of potential get formed around the touchpoint. Each ring has a different potential in decreasing manner. Let’s consider that due to the broken conductor, the potential at the touchpoint is 20KV. Therefore let’s assume the potential of the invisible rings to be 18KV, 16KV, 14KV, and so on.

If a pesron walks in this affected area. The person would experience an electric shock. Because while taking steps, one foot gets on one ring let’s say on the ring with a potential of 14KV and the other foot on the other ring with a potential of 16KV. This creates the potential difference of 2KV between two legs, causing current to flow through the body from high potential ground to low potential ground. Because in this case person’s body is a low resistance path for current to flow than the ground. This is the cause of electric shock due to Step Potential which can be fatal. 

Now how to be safe and avoid such electric shock due to step potential. As we saw, current flows due to the potential difference between two legs as one takes a step to walk. Keep shuffling or bunny hopping with both the legs lifting up and putting down together and not one by one until the person gets out of the affected ground completely. Get at least 10 meters away from the touchpoint. Also, remember not to jump too high. To check whether one is inside the affected area, shuffle out the foot gradually keeping it in contact with the ground. If inside the affected ground, the person would feel a tingling sensation in the legs due to the potential difference. That means furthermore bunny hopping is required to get out of the danger zone, safely.

Now let’s understand Touch Potential. If one touches a high potential conductor or an object. Current flows through the person’s body to the ground, the body being the low resistance path for current to flow. Hence body experiences electric shock which can be fatal. Therefore the way to avoid touch potential is to avoid touching such objects with electric potential, for example, electric poles, conductors, etc.