Motor Disconnecting Means NJATC code calcs 2008

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Motor Disconnecting Means NJATC code calcs 2008
2011-01-14 17:01:55
motors disconnects NEC

Motor disconnecting means general rules and requirements per 2008/11 NEC
Show Answers:

  1. the disconnecting means for motors has 3 responsibilities. What are they? PP168
    • To safely carry the load
    • To be capable of being opened under load, and....
    • To be capable of being opened under locked rotor conditions.
  2. What indicates the locked rotor current of a disconnecting means? PP169

    Can this horsepower rating be the same as the HP rating of the motor? Under what conditions? pp176
    The horsepower rating of the disconnecting means

    Yes: only when the code letter is between A and F
  3. A design B energy efficient motor has a hi/ low starting current? PP169
    Very high
  4. The circuit breaker is/ is not allowed to be used as a disconnecting means for a motor? Why? PP 180
    Is, becuase the UL directory lists them as having been tested for 6 times the devices rating and identified for such use per 430.109
  5. The disconnecting means, versus the branch circuit rating, is rated at _______% of FLC of the motor plus heating loads? PP184
    115%, versus 125% for branch circuits plus 125% of heating.
  6. A molded case switch looks just like a molded case circuit breaker but is different how? PP 185
    No overcurrent protection is built into it
  7. For air-conditioning and refigerant equipment, the branch circuit selection current (BCSC) is always what in comparison to rated load current (RLC)? PP187
    Always bigger
  8. Section 440.32 requires the conductiors supplying a motor compressor to be 125% of the RLC or BCSC, _________. pp188
    whichever is the larger