Electric Grounding Grounding the Electrical System Reference AAVIM “Electrical by awaisjameel555

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									Grounding the Electrical
       System
         Reference: AAVIM
         “Electrical Wiring”
         Created May 2007
 Purpose of the Grounding System

• 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
          NEC Requirements
• 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
               Grounding

• The 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
               Grounded

• Describes the act of being connected to
 the earth or some other conduction body
 that serves in place of the earth
               Bonding

• 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
  Parts of the Electrical System

• Circuits
• Service Entrance Panel
• Metal Water Pipe
• Metal Gas pipe
   Materials in Grounding System

• Must be approved by NEC
The Grounding Electrode System

• All materials must be grounded using
  approved bonding and grounding
  electrode systems
• Check with local building code
             Metallic Pipe

• Water pipe must always be bonded to the
  service entrance panel, grounding
  electrode conductor, or grounding
  electrode
• Other metal pipe, such as gas pipe, which
  may become energized accidentally must
  be bonded to the electrical system
  grounded system
     Use of Bonding Jumper

• To provide CONTINUOUS grounding path
 around devices such as water meters
 installed in metallic water pipe system
Types of Grounding Electrodes
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 Electrode

• Electrode 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
              Ground Ring

• Bare Copper
• At Least #2 AWG or larger
• Encircling residence for a length of 20 feet
• Buried at least 2 ½”
Metal Framework
     Supplemental Electrodes

• 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
               Exceptions

• 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
            Plate Electrode
• 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-clad
  AL and AL-CU may not be used in contact with
    masonry, corrosive, or in direct contact with
    the earth

								
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