Electric Shock and Earthing

When the significant amount of the electric current passes through the parts of the human body there will be the disturbance and excitation of the function of nerves or muscles,termed as electric shock.A sudden discharge of the electricity through the human body is also termed as electric shock.A person occurs the electric shock when he/she came in contact with the electrical energy source.When an electric current flows through any physical body or any objects they absorb the energy and when the amount of absorbed energy is high,affects the body.

Mainly the organ effected when the current flow through the human body is respiratory and heart organ.Many people get electrical shock from the different electrical appliances,electrical circuitry and electrical wires.Whenever the electric current starts flowing through the different parts of human body such as organ,tissues and systems;there is the absorption of electric energy.The nature of observed energy depends upon the the parts of the human body through which the current flows,entry of electric current into body.self-control become fully  disturbed and the hearts stops to function is primary symptom.

pic sources:Electric shock | definition of electric shock by Medical dictionary

There will be the pain at the point of entry and exit of current when the significant amount of current through the body.Contraction of the muscles resulting spasm muscles pain and in torn muscles and ligaments.person becomes fully enable to take the self-protective action due to loss of muscles control. contraction of chest muscles,diaphragm and throat results in the breathing problems.And at last cause the Ventricular fibrillation.

Ventricular fibrillation is case whereby the heart ceases to contract and random twitching of the nervous muscular fibrils occurs.Fibrillation of hearts means cessation of the heart activity,interruption in the functions of the heart and death occurs because of the lack of oxygen.

pic source: Virtual Labs

First aid for Electric shock
  • move the victim to safe place but don`t endanger yourself/
  • De-energizing the electric equipment from the supply switch.
  • Cutting cable or wire to apparatus using a wooden -handle axe.
  • Protect  your eyes against flash.
  • Use the electrical non conductor such as dry stick,dry rope ,leather belt,coat,blanket to move the victim away from the contact.
  • Ascertain whether the patient is breathing or not .If breathing,Then,keep the patient in a reclining comfortable position and loosen all clothing about the neck,chest and abdomen.
  • If the victim is not breathing utilize the Cardiopulmonary resuscitation (CPR).
  • If the heart has ceased beating have a first aid immediately with qualified person.

Safety precautions and Regulations

The best method for the protection against the electric shock is insulation.Insulation of conductor,insulation of worker provides the protection against electric shock.some are the different safety precautions and regulation for electric shock:

  1. Always switch off the mains switch before replacing a blown-fuse.
  2. Always use the correct size of fuse,while replacing blown fuse.
  3. Safety depends upon the good earthing.
  4. Be aware of live wires or conductors bare or insulated.
  5. Before the replacement of any electrical requirements be sure that the switch  is OFF.
  6. Be sue that all the connection are tight.
  7. If you are working on inductive circuit or cable discharges them .
  8. Put the safety belt when you are working above the ground level or pole.
  9. Never disconnect a plug point by pulling the flexible wires.
  10. Never temper unnecessarily with any electrical apparatus.
  11. Never touch an overhead line unless you are sure that it is dead and properly earthed.
  12. Never energized a line unless you are sure that all is clear and no one is working.
  13. while working on motor/Generator make sure that no one can put it on position without your permission.
  14. Never bring a naked light near battery when it is in charged state and maintain the good ventilation.
  15. Must used the rubber mats near electrical panels and switch board.

 

Earthing and shielding Techniques for Personnel and Equipment Protection

What is Grounding or Earthing?

Earthing or the grounding is the connection of metallic parts of an electrical appliance ,electrical machinery and devices to the earth plate or earth electrode through a thick conductor wire.

Earthing is the connection of  neutral point of a power supply system to the earth so as to avoid or minimize danger during discharge of electrical energy.

Need of Earthing or Grounding. Why Earthing is Important?

The primary purpose of earthing is to

  •  avoid or minimize the danger of electrocution fire
  • ensure that the potential of a current carrying conductor does not rise with respect to the earth than its designed insulation.

When the metallic part of electrical appliances (parts that can conduct or allow passage of electric current) comes in contact with a live wire, maybe due to failure of installations or failure in cable insulation, the metal become charged and static charge accumulates on it. If a person touches such a charged metal, the result is a severe shock.

Needs of Earthing
To protect human lives as well as provide safety to electrical devices and appliances from leakage current.
 To keep voltage as constant in the healthy phase (If fault occurs on any one phase).
 To Protect Electric system and buildings form lighting.
 To serve as a return conductor in electric traction system and communication.
 To avoid the risk of fire in electrical installation systems.

Methods of Earthing | Types of Earthing

Earthing can be done in many ways. The various methods are discussed as follows:

1)Plate Earthing:

In plate earthing system, a plate made up of either copper with dimensions 60cm x 60cm x 3.18mm (i.e. 2ft x 2ft x 1/8 in) or galvanized iron (GI) of dimensions 60cm x60cm x 6.35 mm (2ft x 2ft x 1⁄4 in) is buried vertical in the earth (earth pit) which should not be less than 3m (10ft) from the ground level. For proper earthing system, follow the
above mentioned steps in the (Earth Plate introduction) to maintain the moisture condition around the earth electrode or earth plate.

2) Pipe Earthing:

A galvanized steel and a perforated pipe of approved length and diameter is placed vertically in a wet soil in this kind of system of earthing. It is the most common system of earthing. The size of pipe to use depends on the magnitude of current and the type of soil. The dimension of the pipe is usually 40mm (1.5in) in diameter and 2.75m (9ft) in length for ordinary soil or greater for dry and rocky soil. The moisture of the soil will determine the length of the pipe to be buried but usually it should be 4.75m (15.5ft).

3)Rod Earthing

It is the same method as pipe earthing. A copper rod of 12.5mm (1/2 inch) diameter or 16mm (0.6in) diameter of galvanized steel or hollow section 25mm (1inch) of GI pipe of length above 2.5m (8.2 ft) are buried upright in the earth manually or with the help of a pneumatic hammer. The length of embedded electrodes in the soil reduces earth
resistance to a desired value.

 

 

4) Strip or Wire Earthing:

In this method of earthing, strip electrodes of cross-section not less than 25mm x 1.6mm (1in x 0.06in) is buried in a horizontal trenches of a minimum depth of 0.5m. If copper with a cross-section of 25mm x 4mm (1in x 0.15in) is used and a dimension of 3.0mm2if it’s a galvanized iron or steel.If at all round conductors are used, their cross-section area should not be too small, say less than 6.0mm2 ,if it’s a galvanized iron or steel. The length of the conductor buried in the ground would give a sufficient earth resistance and this length should not be less than 15m.

 

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About Er.sushil Neupane 107 Articles
I am Sushil Neupane. I have completed my Bachelor degree in Electrical Engineering(EE) form Tribhuwan university(TU).Currently , I am working at Prabhu IPTV as a Network support Engineer form 2019.I am also engaged in Blogging since 2019.

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