Maricopa Community Colleges  ABC144   19956-20032 
Official Course Description: MCCCD Approval: 04/25/95
ABC144 19956-20032 LEC 1 Credit(s) 1 Period(s)
Grounding
Types of grounding and proper installation of grounds and grounding. OSHA and National Electrical Code (NEC) requirements specific to grounding. Purpose and operation of Ground Fault Circuit Interrupters (GFCI). Effects of soils and environment. Selection of grounds and grounding material for specific situations. Testing grounds with a "megger". Prerequisites: (Indentured status with the Arizona Builders Alliance) or (permission of the apprenticeship coordinator).
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MCCCD Official Course Competencies:
 
ABC144   19956-20032 Grounding
1. Define grounding and explain its purpose. (I)
2. Explain and demonstrate selection and installation of ground and grounding materials for specific electrical systems or equipment. (II)
3. Describe the effect of specific environmental conditions on grounding including: soil, temperature and moisture. (III)
4. Explain OSHA and NEC requirements for electrical systems and equipment grounding. (III, IV, V)
5. Explain the purpose of and operation of a Ground Fault Circuit Interrupters (GFCI). (VI)
6. Explain the operation and function of a "megger" and demonstrate specific testing procedures using a megger. (VII, VIII)
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MCCCD Official Course Outline:
 
ABC144   19956-20032 Grounding
    I. Introduction to Grounding
        A. Trade terms - definition
          1. Equipment grounding conductor
          2. Ground fault
          3. Ground grid
          4. Ground rod
          5. Short circuit
          6. Surge arrester
          7. Other
        B. Purpose of grounding
        C. Grounded vs. grounding
      II. Types of Grounding Systems
          A. System grounding
          B. Equipment grounding
          C. Single-phase systems
        III. OSHA and NEC Requirements
            A. Grounding protection
            B. Grounding methods
              1. Underground water pipe
              2. Metal building frame
              3. Electrodes
              4. Ground ring
              5. Materials
            C. Earth electrodes
            D. Nature of earth electrodes
              1. Resistance of ground rod
              2. Contact resistance between rod and earth
              3. Resistance of surrounding earth
              4. Effective resistance area
            E. Effect of rod size on resistance
            F. Effects of soil resistivity on earth electrode resistance
            G. Factors affecting soils resistivity
              1. Type of soil
              2. Temperature
              3. Moisture content
              4. Chemical content of soil
          IV. Grounding Conductors
              A. Material
                1. Copper
                2. Aluminum
                3. Copper clad aluminum
              B. Splicing
              C. Size requirements
            V. Equipment Grounding
                A. Grounding conductor sizes
                B. Ground continuity
                C. Bonding
                  1. Equipment bonding jumper
                  2. Requirements
                D. Size of equipment grounding conductors
                E. Grounding enclosures
                F. Grounding outlet boxes and devices
                  1. Continuity
                  2. Residential
                  3. Commercial
              VI. Ground Fault Circuit Interrupters
                  A. Location requirements
                  B. Ratings
                    1. Single-pole
                    2. Two-pole
                  C. Operational characteristics
                    1. Single-pole
                    2. Two-pole
                    3. Direct-wired
                    4. Plug-in
                VII. Testing for Effective Grounds
                    A. Megger insulation testers
                    B. Measuring earth resistance
                      1. Step voltage/touch voltage
                      2. Ground resistance
                    C. Megger operation
                      1. Fall-off-potential method
                      2. Three-point testing
                    D. Current supply
                    E. Voltmeter circuit
                    F. Nature of earth electrode resistance
                      1. Components of resistance
                      2. Effective resistance area
                  VIII. Three-Point Testing Procedure
                      A. Electrode spacing
                      B. Grounding resistance curve
                      C. Operating procedure
                      D. Megger
                        1. Operation
                        2. Function
                        3. Testing procedures
                      E. Difficulties in measurement - electrode arrangements
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