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Title: Earthing Systems
Description: All the earthing systems used in domestic purpose. TT, TS, TNC, TNCS
Description: All the earthing systems used in domestic purpose. TT, TS, TNC, TNCS
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Electrical Installation – ECX 4234
513344919
6
...
The potential of an installation is measured with respect to the general mass of the earth or commonly
called earth
...
Neutral earthing: This is important because the performance of the system in terms of short circuits, stability,
protection, etc
...
When the neutral is properly
grounded, voltages of the phases are limited to near phase to ground voltage
...
This is governed by various regulations such as the IEE regulations
...
6
...
These are
TN - earthing of the installation is done to that supplied by the supply authority
TT - supply authority earth and the installation earth is independent
IT - supply authority has effectively an isolated neutral and the installation has an
independent earth
In these, the first letter denotes the earthing arrangement at the supply authority side and the
second letter denotes the relationship of the exposed conductive parts of the installation to earth
...
With the Second letter, T denotes a direct
electrical connection of the exposed conductive parts of the consumers installation to earth,
independently of the earthing of any point of the supply authority side, while N denotes a direct
Page 21
Electrical Installation – ECX 4234
513344919
electrical connection of the exposed conductive parts to the earthed point of the supply authority
side, which for ac is usually the neutral point
...
Even the details of the earthing systems other than the one used in Sri Lanka will not be
dealt with in this course]
6
...
In this system, the supply is earthed
at the source end, and all exposed-conductive parts of the installation are connected to an electrically
independent earth electrode at the consumer end
...
A circuit protective conductor connects exposed conductive parts of equipment to the
main earthing terminal
...
The resistance of this electrode to earth also depends on the condition of soil and may have
values in excess of 100 Ω
...
Page 22
Electrical Installation – ECX 4234
513344919
Necessary equipment for domestic earthing system
earth rod (GI or CU)
earth cable that connected with domestics circuit
earth pit
earth clamp or connecting nut & bolts
Page 23
Title: Earthing Systems
Description: All the earthing systems used in domestic purpose. TT, TS, TNC, TNCS
Description: All the earthing systems used in domestic purpose. TT, TS, TNC, TNCS