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 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 Assures the system will work properly while preventing damage to the system

3. NEC Requirements All electrical systems serving structure must be bonded together All electrical systems serving structure must be bonded together Including the following 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 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 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 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 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 May be caused by power surges, lightning strikes or other types of ground fault type occurences

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

9. Materials in Grounding System Must be approved by NEC Must be approved by NEC

10. The Grounding Electrode System All materials must be grounded using approved bonding and grounding electrode systems All materials must be grounded using approved bonding and grounding electrode systems Check with local building code 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 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 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 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 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 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 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 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 Electrodes must be at least 20 feet in length and consist of one or more ½” steel reinforcement bars

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

17. Metal Framework

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

19. Rod and Pipe Electrodes Iron or steel rod electrodes Iron or steel rod electrodes Must be 5/8” in diameter Must be 5/8” in diameter Pipe must be ¾” in diameter Pipe must be ¾” in diameter Galvanized or metal coated for corrosion resistance Galvanized or metal coated for corrosion resistance 8 feet in length 8 feet in length Installed to a depth of 8” in direct contact with earth Installed to a depth of 8” in direct contact with earth

20. Nonferrous rods must be listed at no less than ½” Nonferrous rods must be listed at no less than ½” Stainless Steel- ½” diamter Stainless Steel- ½” diamter Must be at or below ground level Must be at or below ground level Must be protected from physical damage 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 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 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 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: 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 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 Steel/Iron Plate electrode must be ¼” thick Non-ferrous metal plate must be 0.06” thick Non-ferrous metal plate must be 0.06” thick 2 feet square 2 feet square Buried at least 2 1/2’ Buried at least 2 1/2’

24. Grounding Electrode Conductor NEC permits 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