ELT 178 - Electrical Grounding

1. Discuss the purpose of grounding using Article 250 in the NEC®.
   1. Understand the sequence of Article 250 in the NEC®.
   2. Identify the terms used in Article 250 in the NEC®.
   3. Explain why electrical circuits are grounded.
   4. Explain the meaning of effective grounding.
   5. Explain the relationship of voltage and current to electric shock.
   6. Explain the resistance of the human body.
   7. Understand the importance of bonding enclosures to ground.
2. Illustrate the characteristics of various faults.
   1. Explain the difference between a direct short and a ground fault.
   2. Discuss the various stresses on electrical equipment cased by electrical faults.
3. Develop and illustrate the characteristics and requirements of the grounding electrode system.
   1. Explain the purpose of a grounding electrode.
   2. Understand the requirements for concrete incased electrode.
   3. Discuss the ground rod and how resistance is measured.
   4. Explain the purpose of bonding two or more electrodes together when installed for a single building.
   5. Explain the connections when more than one service is installed to the same building.
   6. Explain the characteristics and requirements of the grounding electrode conductor.
4. Illustrate the characteristics and requirements of circuits and system grounding.
   1. Define term grounded conductor.
   2. Explain the differences of systems grounded and circuit grounded.
   3. Explain the term voltage to ground.
   4. Identify which systems and circuits shall be grounded.
   5. Identify which systems are permitted to be grounded.
   6. Explain and interpret the installation requirements of impedance-grounded systems.
5. Illustrate the characteristics of the grounded conductor.
   1. Distinguish the difference grounded and not grounded.
   2. Discuss voltage to ground.
   3. Explain the difference between AC and DC ground requirements.
   4. Identify the high-leg of a delta system.
   5. Explain the requirements of isolated systems.
   6. Discuss impedance grounding requirements for AC systems.
6. Develop and illustrate the characteristics and requirements of main bonding jumpers.
   1. Describe the location of the main bounding jumper.
   2. Discuss how main bonding jumpers are installed.
   3. Calculate main bonding jumper using table 250.66 in the NEC®.
   4. Calculate the size of the main bonding jumper using the same material.
   5. Calculate the size of the main bonding jumper using different material.
   6. Calculate the size of the main bonding jumper when installed in parallel.
7. Develop and illustrate the characteristics of equipment grounding.
   1. Define what an equipment grounding conductor is.
   2. Identify fault that occur when installing equipment ground.
   3. Explain using raceways and enclosures for correct equipment ground.
   4. Discuss the identification of various equipment grounding.
   5. Discuss various materials used permitted for equipment ground.
   6. Calculate equipment grounding using table 250.122 (for single raceway) in the NEC®.
   7. Calculate the size of the equipment ground when installed in parallel.
   8. Calculate the size of the equipment ground when the circuit is protected by instantaneous breaker.
8. Develop and illustrate the characteristics of equipment and enclosure bonding.
   1. Discuss the term bonding.
   2. Explain continuity of the equipment grounding path.
   3. Explain bonding requirements on the supply side of service disconnect.
   4. Explain bonding requirements on the load side of service equipment.
9. Develop and illustrate the characteristics and requirements ground fault protective equipment.
   1. Identify when ground fault protection of equipment is required at service.
   2. Identify when ground fault protection is needed on feeders.
   3. Explain the operation of the ground fault circuit interrupter (GFCI).