Motor Disconnecting Means NJATC code calcs 2008

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.
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
A design B energy efficient motor has a hi/ low starting current? PP169

Very high
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
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.
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
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
Section 440.32 requires the conductiors supplying a motor compressor to be 125% of the RLC or BCSC, _________. pp188

whichever is the larger

Author

johnbowens

59846

Card Set

Motor Disconnecting Means NJATC code calcs 2008

Description

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

Updated

2011-01-14T22:01:55Z

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