NCEES Review Power Prob 505

[cabby]

Squirrel cage motor, 40HP, 460V, 3 phase, 60hz, 52A, .87PF lagging. what is the maximum locked-rotor current for selection of the motor disconnect?

Has any one worked this yet? I am using the formula in the NEC Handbook Section 430.7, however, I get 251A and the book's solution is 412A. What am I missing?

thank you,

cabby

 

[NVRSTOP]

That question refers to the 2002 NEC which included Table 430.151, B. This Table included Design E motors. The 2005 NEC has been revised and Table 430.251, B replaced Table 430.151, B but does not include Design E motors.

You are using the correct Table, this question is out of date for the current (2005) NEC that is being used for the exam at this time.