Maricopa Community Colleges  ABA201   19964-20032 
Official Course Description: MCCCD Approval: 04/23/96
ABA201 19964-20032 LEC 0.50 Credit(s) 0.50 Period(s)
Overcurrent Protection
Overcurrent protection including terminology, safety factors, conformance to the National Electrical Code (NEC), fuses, circuit breakers and short circuits. Selection and sizing of overcurrent protection. Prerequisites: (Indentured status with the Arizona Builders Alliance and ABC132) or permission of the apprenticeship coordinator.
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MCCCD Official Course Competencies:
 
ABA201   19964-20032 Overcurrent Protection
1. List and define specific electrical terminology associated with overcurrent protection. (I)
2. Explain the importance of overcurrent protection as it relates to life safety and to protection of systems and equipment. (I)
3. Explain the operation and specific uses of fuses and circuit breakers. (II, III, IV, VI)
4. Calculate "peak and root mean square (RMS)" values for specific current limiting devices and size conductors for specific Loads. (V)
5. Explain the use of single element and dual element fuses in motor circuits. (V)
6. Select and size overcurrent protection for specific applications. (VII)
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MCCCD Official Course Outline:
 
ABA201   19964-20032 Overcurrent Protection
    I. Overcurrent protection
        A. Terminology
          1. ampere rating
          2. arcing time
          3. current limitations
          4. high-speed fuses
          5. interrupting capacity 6. m elting time
          7. overLoad
          8. peak let-through current
          9. resistive Load
          10. short circuit
          11. voltage rating
          12. other
        B. Importance of overcurrent protection
          1. life safety
          2. facility downtime
        C. OverLoads
        D. Short circuits
          1. current at fault levels
          2. current at operating levels
          3. interrupting rating
      II. Fuseology
          A. Voltage rating
          B. Ampere rating
          C. Interrupting rating safe operation
          D. Selective coordination
          E. Current limitations
            1. non-current limiting device
            2. current limiting device
        III. Operating principles of fuses
            A. Non-time delay fuses
            B. Dual-element time delay fuses
          IV. United Laboratories (UL) fuse classes
              A. Fuse types
                1. class "R"
                2. class "CC"
                3. class "G"
                4. class "H"
                5. class "J"
                6. class "K"
                7. class "L"
                8. class "T"
              B. Branch circuit listed fuses
              C. Medium voltage fuses
                1. general purpose current-limiting
                2. back-up current-limiting
                3. expulsion
              D. Application of medium voltage fuses
                1. voltage
                2. continuous current-carrying fuses
                3. interrupt rating
              E. Current limiting fuses
              F. Fuses for selective coordination
              G. Fuse time-current curves
              H. Peak let-through charts
            V. Motor overLoad and short-circuit protection
                A. Single element fuse
                B. Dual-element fuse
              VI. Circuit breakers
                  A. Component parts
                    1. contacts
                    2. magnetic trip element
                    3. thermal trip element
                    4. line and Load terminals
                    5. bussing
                    6. insulated housing
                  B. Ranges in amperes
                    1. 15 - 100
                    2. 125 - 225
                    3. 250 - 400
                    4. 500 - 1000
                    5. 1200 - 2000
                  C. Interrupt capacity rating
                VII. Overcurrent protection applications
                    A. NEC sections
                      1. 240-3
                      2. 240-1
                      3. 110-10
                      4. 240-6
                    B. Fuse locations
                      1. NEC 240-21
                      2. exceptions
                    C. Lighting/appliance Loads
                    D. Feeder circuits with no motor Load
                    E. Service equipment
                    F. Transformer secondary conductors
                    G. Motor circuit protection
                      1. overLoads
                      2. short circuits
                      3. NEC regulations
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