The concept of step voltage and ways to overcome it
Hazard identification
What is step voltage - this is the voltage that can occur near a fallen working wire or cable, spreading over the surface of the earth and creating a dangerous potential between two points, at the distance of one step of a person (the usual step of an adult man is about 80 cm). Depending on the voltage and the distance to the point of contact of the wire and the location of a person, this value can reach from ten to several thousand volts per step.
Often, after a storm, fallen trees fall on overhead lines, breaking wires or breaking supports to throw overhead lines to the ground, thus creating the cause of this phenomenon and the danger of potential in the area of possible damage. During such accidents, shutdown at the substation occurs in several stages. First, voltage is automatically reapplied, checking whether the cause has been eliminated. This is necessary if it is possible the cause has eliminated itself by freeing the line from its branches or paws in the case of small animals or birds, which inadvertently blocked the air insulator. There is no guarantee that the automation will work out clearly by detecting a break or sagging wire with a swinging branch and disconnecting the line.
When crossing power lines, make sure there are no dangling wires or cables lying on the trees in your path. Current also diverges along the trunk, creating potential around it.
You can view an example of a dangerous situation in the video:
Safe exit from the affected area
A safe distance is more than 20 meters from a source of high potential. Despite this, it is believed that the maximum radius of damage to the step voltage is 8 meters if the hazardous voltage at the breakpoint is above 1000 volts and 5 meters if the value does not exceed 1000 volts.
At the same time, starting from 380 V and higher, the voltage is considered dangerous, because able to cause such a step potential. To leave the danger zone, it’s safe to leave, you do not need to run fast, taking long steps. The step voltage increases with increasing step length, and vice versa. While the legs are near a threat to life will not arise. It is necessary to leave the zone of high electric potential by stepping from one foot to another, making a small step within the size of the foot (this movement is also called the goose step).In no case do not try to jump out of the affected area on one leg. This method of exit is certainly effective, but if you fall on your hands or elbows, a step voltage of a higher magnitude will occur, which can immediately lead to death.
Effective remedies for this danger are galoshes and gloves made of dielectric rubber. If suddenly you have such means at hand, you definitely need to move into them.
You can also familiarize yourself with the conditions for safe exit from the spreading zone of electric current by watching video tutorials:
How to free a person?
If you were not alone and your companion in front suddenly fell, falling into the zone of spreading of step voltage, because the electric current caused an involuntary contraction of the leg muscles, do not rush towards it. It is necessary to assess the situation and approach it in small steps, wrapping hands in dry clothes, pulling the victim out of the affected area.
Under the step voltage, you can get at home, touching a faulty electrical device connected to the network, thus forming an electrical circuit. In order to avoid such accidents in the dashboard, it is necessary install an RCD or organize a grounding system together with a potential equalization system.
What to do if before your eyes a person is exposed to an electric current in a room? Do not panic, the first thing you need to break the circuit by turning off the switch or the power switch. If this is not possible, with a dry wooden object, wrapping dry clothes around your hands, remembering your safety, try to free the victim by this object, folding it or placing it between a person and a source to break the chain. The pictures below show the measures that need to be taken to release the victim, including after the defeat by step voltage:
Having liberated the person, pull him to a safe place, feel the pulse and look at the reaction of the pupils to the light. Call an ambulance and begin emergency cardiopulmonary resuscitation, artificial respiration and heart massage, before the ambulance arrives.
If the victim regains consciousness, lay him on his side so that the sudden gag reflex does not get into the airways. You can find more visual step-by-step actions in our article - how to help with electric shock. Remember that every point in the rules is the life or the bitter experience of the victim.
That's all I wanted to tell you about what step voltage is, what is the reason for its occurrence and most importantly - how to identify the danger and leave this zone. Take care of yourself and remind you again - go around the tattered wires for at least 8 meters, because at this distance, the dangerous potential is reduced to zero.
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