1. Grounding the Electrical System
Reference: AAVIM
“Electrical Wiring”
Created May 2007

2. 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

3. 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

4. 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

5. Grounded
Describes the act of being connected to the earth or some other conduction body that serves in place of the earth

6. 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

7. 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

8. Parts of the Electrical System
Circuits
Service Entrance Panel
Metal Water Pipe
Metal Gas pipe

9. Materials in Grounding System
Must be approved by NEC

10. The Grounding Electrode System
All materials must be grounded using approved bonding and grounding electrode systems
Check with local building code

11. 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

12. Use of Bonding Jumper
To provide CONTINUOUS grounding path around devices such as water meters installed in metallic water pipe system

13. Types of Grounding Electrodes

14. 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

15. 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

16. Ground Ring Bare Copper At Least #2 AWG or larger
Encircling residence for a length of 20 feet
Buried at least 2 ½”

17. Metal Framework

18. Supplemental Electrodes
Typically made of metal rods, pipes, or plates

19. 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

20. 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

21. 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

22. 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

23. 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’

24. 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