earthing and grounding
DESCRIPTION
Earthing and Grounding BasicsTRANSCRIPT
SOLANKI
KAUSHAL
CHAVDAMOHIT
Fundamental to the safety of those installing, using, and servicing the electrical system
Assures the system will work properly while preventing damage to the system
All electrical systems serving structure must be bonded together
Including the following Electrical wiring system Telephone system Phone system Burgular alarm system Cable or satellite system
GroundingThe process of making a planned, continuous,
connection between NON-CURRENT CARRYING parts of the electrical wiring installation and the earth and some other conducting body
Process in which all NON-CURRENT CARRYING METALLIC parts of the electrical wiring system are permanently joined together to form a CONTINUOUS grounding path
Bonding
Reduces the differences in potential between each electrical system
May be caused by power surges, lightning strikes or other types of ground fault type occurences
Circuits Service Entrance Panel Metal Water Pipe Metal Gas pipe
Materials in Grounding System
•Must be approved by NEC
All materials must be grounded using approved bonding and grounding electrode systems
Check with local building code
Use of Bonding Jumper
• To provide CONTINUOUS grounding path around devices such as water meters installed in metallic water pipe system
Metal Underground Water Pipe Must be bonded to the supplemental
grounding system electrode and to the neutral bus bar in the SEP
Connection must be made within 5 feet of entering structure
Water pipe must be in direct contact with the earth for at least 10 feet
Concrete Encased ElectrodeElectrode encased in foundation footing
covered with at least 2 inches of concrete Electrodes must be at least 20 feet in length
and consist of one or more ½” steel reinforcement bars
Bare Copper At Least #2 AWG or larger Encircling residence for a length of 20
feet Buried at least 2 ½”
Typically made of metal rods, pipes, or plates
Rod and Pipe Electrodes Iron or steel rod electrodes Must be 5/8” in diameter Pipe must be ¾” in diameter Galvanized or metal coated for corrosion
resistance 8 feet in length Installed to a depth of 8” in direct contact
with earth
Nonferrous rods must be listed at no less than ½”
Stainless Steel- ½” diamter Must be at or below ground level Must be protected from physical
damage
ExceptionsExceptions
If electrode can not be driven more than 4” into the earth b/c of rock or other obstruction
May be driven at an oblique and of no more than 45° from vertical
At least 8” of the electrode must be in contact with earth
Multiple grounding rods•When more than one electrode grounding
rod is used:▫Must be installed not less than 6 feet apart▫Must be bonded together with an approved
bonding jumper to form single grounding electrode system
May be used in areas where it is not possible to use a grounding rod or ring
Steel/Iron Plate electrode must be ¼” thick Non-ferrous metal plate must be 0.06” thick 2 feet square Buried at least 2 1/2’
Grounding Electrode Conductor NEC permits
Copper Aluminium Copper-cladAL and AL-CU may not be used in contact
with masonry, corrosive, or in direct contact with the earth
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