The best method for providing overcurrent protection for most circuits is to use a circuit breaker that combines overcurrent protection with short-circuit and ground-fault protection. However, this isn't usually the best choice for motors. With rare exceptions, the best method for providing overcurrent protection in these cases is to separate the overload protection devices from the short-circuit
Are any of the following statements true for a 1-hp, 120V motor, nameplate current rating of 14A?
Please take a look at some incorrection
1. 1-hp@ 120v motor exists only as DC type (see T.430.27) FLC 9.5A
but you use 1-hp AC current value
2. 1-hp single phase AC motor is related to 115V, not 120V (.430.28) FLC 16A
3.THHN cable relates to 90C group (HH means 90C)
why did you use 60C column to determine wire size? There is no THHN @60C cable.
4. Never said that we have to use in this particular task inverse time breaker,not instaneous trip type,but you choose 250% rate. Why? By common sense?
Per my opinion, this example given in very sloppy (I would say unfair) state and,if you,God forbid, get it diring computer based electrical exam,you will definitely click the wrong answer even your calculation is perfecly correct.
Thanks. Andrew-Electrician
Motor Calculations
