codes&practices3.txt

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Author:
Anonymous
ID:
49492
Filename:
codes&practices3.txt
Updated:
2010-11-14 16:02:19
Tags:
electrical OCPD
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Description:
OCPD and the NEC
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  1. 1. Typically an OCPD is rated at ________% of the continuous load current. An exception to this general rule that allows a sizing at a larger percentage would be_______ loads. Wb 8
    • 125%
    • motor
  2. 2. A circuit breaker with a slash rating, such as 120/240, shall be permitted to be applied in a ________ grounded system. Pp 11
    Solidly. Not in a corner grounded, resistance grounded, or ungrounded system
  3. 3. Branch circuit ocpd�s are never rated less than ________ amperes interrupting rating. Pp 10
    5000 amps
  4. 4. Dual element fuses generally are permitted to be sized up to _______% and an inverse time circuit breaker up to ____% of the motor full load amperes. Pp 12
    • 175%
    • 250%
  5. 5. According to 240.83(C) the interrupting rating of an OCPD is/ is not required to be marked on a circuit breaker used for supplementary protection. Pp 15
    Is not
  6. 6. The mechanical trip unit on a circuit breaker can be _______ magnetic, ________only, or __________ trip. Pp 17
    • Thermal
    • Magnetic
    • Electronic
  7. 7. A branch circuit breaker can be thermal magnetic, electronic trip, or ____________. Pp20
    Current limiting.
  8. 8. A(n) ________element is often used to trip a thermal magnetic trip circuit breaker on an overload condition. Pp 18
    Bi-metal
  9. 9. The __________ portion of a molded case circuit breaker is used for overload protection. Pp21
    Thermal trip
  10. 10. Low voltage circuit breaker are typically used where _________ or _________ ability is required for maintenance. Pp 24
    Draw out capability or selective coordination
  11. 11. Thermal magnetic molded case circuit breakers are also known as _______ ______ circuit breakers. This is because the higher the overcurrent, the faster the breaker trips. Pp20
    Inverse time
  12. 12. For a 20A circuit breaker the fixed instantaneous setting may be _____ times the circuit breaker rating. Pp 22
    8
  13. 13. What kind of circuit breaker is not considered used in branch circuits and typically cannot replace the thermal magnetic or electronic trip circuit breaker? Pp 23
    Magnetic only trip circuit breakers often referred to as mag- only, or instantaneous trip only circuit breakers.
  14. 14. One benefit of current-limiting fuses is a high _________ rating, typically _________ A or higher. Pp27
    • Interrupting
    • 200,000
  15. 15. Non-time delay (fast acting) fuses us a _______element. Pp 27
    Single
  16. 16. A time delay fuse is a single or dual element fuse? Pp27
    Dual- element

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