this presentation is about electric shock and earthing presented in western region campus by two students of same campus

1. Presentation by:
Kishor Ghimire(222)
Ramesh Adhikari(233)

2.  Electric shock is the physiological
reaction or injury occurs when the
human body becomes part of the path
through which current flows

3. BASIC CIRCUIT ANALYSIS

4. The current strength

5. The body resistance
Frequency of current
The path taken by the current
Duration of the contact
Area of contact
FACTOR DETERMINING
SHOCK INTENSITY CONTD..

6. Execution by electrocution electric chair, employed as an official
method of capital punishment developed throughout the 1880s
Researchers found electroconvulsive therapy (ECT) to be more
effective than the use of drugs to treat short-term depression

7. Electric Fencing

9. Artificial respiration Mouth to mouth respiration

10. WHAT IS EARTHING?
Connections of neutral parts of the
electrical equipment to the general
mass of the earth for immediate
discharge of electric energy
without danger.

11. The PRIMARY goal is
SAFETY.
Why ground at all?
PERSONNEL SAFETY
FIRST
EQUIPMENT
PROTECTION
SECOND

12. EARTHING
SYSTEM
EARTHING
Deals with the Earthing
of current carrying parts
of the equipment
EQUIPMENT
EARTHING
Deals with the Earthing of
non- current carrying parts of
the equipment

13. Ground rod
Simplest form is a
SINGLE STAKE
Mostly used for:
• Lightning
protection
• Stand alone
structures
• Back-up for utility
ground

14. Ground rod group
typically for
lightning
protection on
larger structures
or protection
around potential
hotspots such as
substations

15. For areas
where there is
rock (or other
poor
conducting
material) fairly
close to the
surface Ground plate

16. Ground mesh
 A ground mesh
consists of network
of bars connected
together, this
system is often
used at larger sites
such as electrical
substations.

17. Soil type. Soil resistivity varies widely
depending on soil type, from as low as
1 Ohmmeter for moist loamy top soil to
almost 10,000 Ohm-meters for surface
limestone.

20. RESISTIVITY MEASUREMENT ( WENNER METHOD)
Resistivity measurements are
performed by using a four wire
method.
Used to determine which KIND of earthing
should used, BEFORE placing earth stakes.

21. The distance between the earth ground stacks is at least three times
greater than the stake depth.
The soil resistivity measurement are often corrupted by the existence
of ground currents and their harmonics. It uses Automatic Frequency
Control (AFC) system to prevent from it.

22. RESISTIVITY MEASUREMENT
From the indicated resistance value RE,
the soil resistivity is calculated according
to the equation :
E = 2  . a . RE
E ...... mean value of soil resistivity (W.m)
RE ...... measured resistance (W)
a ...... probe distance (m)

23. Decreasing the ground resistance of a
grounding system in high resistivity soil is
often a formidable task.
Recently, some new methods have been
proposed to decrease ground resistance.

27. Chemical rods are electrodes with
holes along their length, filled with
mineral salts.
The rod absorbs moisture from both
air and soil.