Electrical calculation book seems off again

[Jpflex]

When trying to figure the feeder conductor demand in VA for several motors, I would think it would not make a difference if this service / feeder is for a commercial building. (Calculating feeder load demand for commercial buildings)

Apparently my code calculations book is not calculating the way I remember or learned from other books.

In this code calculations books, it says:

Three 1/3 hp, 120 volt single phase motors are to be installed for ventilation purpose in a variety store. Calculate the full-load current FLC of the FEEDER DEMAND (VA to be applied to the feeder) for the single phase motors.

The book then shows
Table 430.248

1/3 hp at 120 volts FLC = 7.2 amperes

VA = E x I x 3
2,592 VA = 120 E x 7.2i x 3

Answer 2,592 VA noncontinuous and neutral conductor load (to be applied to the feeder)



However what happened to 125% of the largest motor plus the sum of the remaining motor FLCs? Or if all motors are equal, wouldn’t you take 1 motor FLC x 125% plus the sum of remaining motor FLC

7.2 x 1.25 + 7.2 + 7.2 = 23.4i
23.4i x 120E = 2,808 VA but not 2,592 VA

Why is there a discrepancy here?

 

[Jpflex]

The book is making a distinction apparently to not apply the extra 25% to a single motor if all motors are equal. The book says section 430.24 problem 8-35 follows 430.24 (2) SINCE NONE OF THESE MOTOR LOADS WILL BE CONSIDERED THE LARGEST MOTOR LOAD.

On the final step it only adds the extra 25% if a motor is larger than the rest.

 

[Jpflex]

Update. I believe u got this error figured out!

 

[Tulsa Electrician]

Did you mean, you have figured it out?

Update. I believe u got this error figured out!

 

[ptonsparky]

Whose book is this?

 

[Jpflex]

Whose book is this?

It is one of my books.

 

[Jpflex]

Did you mean, you have figured it out?

Yes I believe so. I was trying to say that I found what happened. It looks lii look me the book added another motor later and so these motors did not get the additional 25% added

 

[ptonsparky]

It is one of my books.

I meant author.