This is an educative article that I will categorize under safety and training, to engineers and the general public. Its based on an accident situation but it doesn’t mean, you shouldn’t try to prevent such conditions from ever happening, especially to power station workers which I suppose should already know this. Do ensure to broaden your knowledge on general safety situations, especially this(electricity) because it knows no one. It can happen anytime, anywhere and to anyone and consequently result in death.
ELECTRICITY IS NOT TO BE JOKED WITH
No one can ever be a complete electricity expert. It is one of the deadliest parts of engineering. One wrong move and you die without even a slight chance of reparation. Statistics and news from where I come from, Nigeria and even other countries have it that a lot of people suffer the injury of electric shock and die of electrocution from artificial electricity even more than the casualties of a lightning strike. My heart ached when I lost a distant acquaintance last year as a result of electrocution. This, I don't wish for anyone. General possible causes are improper installation of and degraded power cables and most victims are electricians, electrical engineers and other electric professionals.
STRAY VOLTAGE
(Dealing with Alternating current(AC))
An unwanted and undesired rise of electric potential occurs usually when electrical connections are not faultless. Naturally and inevitably, general electric circuits connections need to be completely interlinked when receiving energy from a source of which the earth(ground) is a component - a conductor completing the electric circuit. Electronic circuits and objects connect to the ground on one end and a conductor known as neutral(with no potential) runs from the ground from another end back to the source to ensure uninterrupted current flow. An inevitable Neutral to earth Voltage (NEV) generates as this current flows on the finite impedance of the neutral.
Situations occur when voltage occurs between two conductive surfaces that can synchronously be in touch with a man. Terminologically (not our main focus though), ordinarily, when the voltage is low, it is called stray voltage but in uncommon conditions, when such situation is hazardous to man because of an elevated voltage, it is called contact voltage. Anyways screw Engineering English as long as we know what we're dealing with here - HOW WE CAN BE SAFE.
HUMAN JUMPER CABLE
Ever wondered how and why you get shocked when you touch a naked energized cable but luckily if wearing a footwear made of leather or rubber made especially as an insulator can escape this injury.
Recap,
The ground is already part of the circuit as electric lines are grounded. Your feet were on it before touching the cable and you became part of the circuit like a conductor. I’d say you were grounded and since a difference in potential – Voltage gradient exists between the two contact points you got shocked.
YOU ARE A JUMPER CABLE, AREN'T YOU?
HA....... I'LL USE YOU FOR MY NEXT CIRCUIT DESIGN
Good insulating shoes prevent this, whenever electricity flows into your body. Electric flow through your body is obstructed by the shoe and since current always need an unbroken conducting route of which now your body isn’t, it continues its journey through the electric cable and your body is no more a jumper cable.
Note: The higher the distance between the two contact points, the higher the potential difference and the risk.
Warning: This experiment shouldn’t be practised by anyone who isn’t an electrical expert. Insulators may fail at any time because electricity can always find the thinnest route through it to pass through, especially when dealing with AC. Recall that in chemistry, all material, elements and compounds even wood, rubber and any other insulator have electrons, although they need an infinite electric drive to move which is impossible. I simply mean dealing with electrical connections, especially for the unskillful, require the use of wears specially made for insulation purposes.
TOUCH AND STEP POTENTIAL
In a state where there is a contact or stray voltage within a perimeter maybe as a result of downed or degraded power lines and inadvertently someone finds himself in that area, he or she may become a human jumper cable. A high potential exists close to the pole(point of contact) which diminishes as distance increases away from it, this causes a big potential difference between the pole area and a distant point— Voltage Gradient.
Taking steps that are largely apart on such energized ground adds a person to the circuit and can pose a risk of electrocution. This is a step potential as a voltage exists between the person’s feet.
On the other hand, one can still be a conductor even if the two feet are very close and placed on the ground. Placing a body part such as your hand on another energized body as a result of the same contact voltage, maybe a pole, vehicle or even still, the ground and simultaneously stepping on the ground poses a risk called touch potential, as a potential difference exists between your hand and your leg.
Popping Off – Downed Power Lines
Here is the core. Be focused and relax, or get on the dance floor.
Suppose you accidentally find your self on a ground where there are downed power lines. They may not have electric flow but it is safe to assume danger because the probability of it being energized is close to one. Definitely, it’d be the first option to call for safety using a phone, and defining to them your location so that they can cut off power supply in that area for a safe escape. But when circumstances don’t allow this, switch to an alternative – plan B. Remember that one wrong move will surely....... D..I..E!!.
One may face the risk of step POTENTIAL if not careful. Luckily, if you are able to scale through, you’ll realize that you may be able to dance.
MOON WALK | SHUFFLING
A popular dance step of a late musician, Michael Jackson, who was at a time the king of hip-hop.
In such hazardous situations, one would have to perform this dance step, in a forward direction. Walking out of that perimeter safely requires the person taking short sliding steps without lifting legs–shuffling. Placing just a foot on the ground and wanting to take a normal long step, is like the energized ground calling you forth to join in the chain of energy receptors, and get electrocuted. At that point, the person is like a long cable with one connected end waiting for the second end to be connected to complete the circuit route.
Note: while your feet are on the ground, a contact of any other part of your body with any conductive material within the perimeter can also pose a risk of touch potential, so long the circuit goes on. Be careful not to touch anything.
A lot harder than shuffling, HOPPING
Safety against step potential requires not just shuffling but also a hopping motion. It is incumbent that no path is created for current to pass through. Hopping with just a foot is actually safer if it can be done carefully but if the person trips and falls, that’s the E..N..D. When hopping on both feet, one should make sure both feet land at the same time with no distance apart. I suggest you go for shuffling, that's a lot safer and easier
Shuffling Theory
I haven’t seen any testimony on this and I’m not one myself. So I apologize to you all because I know that many people prefer practical and actions to theories. But the least I’ll do is explain how it works.
By now you already understand that electricity needs a pathway to move, and it moves whenever there is a voltage gradient i.e. moving from point higher voltage to point of lover voltage. Placing legs together while shuffling away from a step potential prevents both legs scaling a voltage gradient. Since the two feet are almost on the same point they have little or no potential difference which keeps you safe from electric shock. This simply means that the electricity journey continues only through the ground and not the person’s legs.
Not a hard theory right?..... BE SAFE.....
STAY TUNED.........
REFERENCES
What Is Step and Touch Potential and Reducing Resistance To Ground? | Stray Voltage | -Electrical Safety
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