# Kaplan NEC Problem



## Frontier05 (Oct 25, 2006)

Looks like some funky code stuff going on there.

Work calls though. I'll try to post later.


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## Wolverine (Oct 25, 2006)

One of the practice problems calculating wire size from the NEC Codebook involved derating the wire, derating it again, derating it a third time, then undoing the first derate based on fine print in line X of Paragraph Y of Subsection Z, Note #Q. I could get three but the fourth adjustment killed me.

How funky will the code stuff be on the Exam? I'm good to two, maybe three levels of funkiness. Four is no good and five is right out.

:drunk:

_Wake me up when October ends_


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## FusionWhite (Oct 25, 2006)

> One of the practice problems calculating wire size from the NEC Codebook involved derating the wire, derating it again, derating it a third time, then undoing the first derate based on fine print in line X of Paragraph Y of Subsection Z, Note #Q. I could get three but the fourth adjustment killed me.
> How funky will the code stuff be on the Exam? I'm good to two, maybe three levels of funkiness. Four is no good and five is right out.
> 
> :drunk:
> ...


The answer is and always will be C.


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## Wolverine (Oct 25, 2006)

That's what I'm saying... C would be answer number three and I'm pretty sure I can get that far, including A and B, but what if the answer is "D", then what do I do? D is too funky for me.


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## Frontier05 (Oct 25, 2006)

Hahahaha. Maybe I should have chosen a different word beside funky. Guess most things funky are not a good thing!

Looks like Kaplin let some get by: Problem #1.22-1.26

The code references are old being it?s still using the dash notation.

Problem 122. The answer they selected is a direct NEC code violation. This is a building, buildings are at 60 Hz cycles, not some control device or an airplane that operates at higher frequency

Problem 124: Obviously factors like harmonics are taken into consideration as well and unbalance. Choosing the neutral the same as the phase conductor is a very sound engineering decision, but it?s not per NEC minimums. Neutral sizing is per NEC 220.61

Problem 125: This is using chap 9 table 5 which is standard aluminum. Most building today, that are approved to use aluminum, use compact aluminum on table 5A. It reduces conduit size being the diameters are different. The problem doesn't specify so how do you know which table to use??

Problem 126: Obviously this GEC size will change due to the change needed to be made in #122 above.

Agree?

Kaplin 4.38 should say three phase, not single.


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## Frontier05 (Oct 25, 2006)

> One of the practice problems calculating wire size from the NEC Codebook involved derating the wire, derating it again, derating it a third time, then undoing the first derate based on fine print in line X of Paragraph Y of Subsection Z, Note #Q. I could get three but the fourth adjustment killed me.
> How funky will the code stuff be on the Exam? I'm good to two, maybe three levels of funkiness. Four is no good and five is right out.
> 
> :drunk:
> ...


There are two requirements in the NEC for derating ampacities that I know of:

1: ambient temperature

2: number of conductors in a raceway or cable.

Lug termination is also considered, but that?s really factored into using the conductor table correctly (I think it?s 310.16).

There is a temp derating conversion at the fine print note below the conductor chart, I think it?s Nec table 310.16. Ambient temperatures exceeding 86?F must be derated ? say your running conduits with wire on a roof in Phoenix Arizona, ummm, you wanna derate that puppy!! Around the same area as the table, you also need to derate for multiple current carrying conductors over a certain amount ( I don?t have a code book handy to look), but it gives a derate percentage per the current carry conductor amount in each conduit run.


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## Wolverine (Oct 26, 2006)

From (fried) memory, the derates in the problem were:

1.) Temperature adjustment,

2.) Multiple conductor in raceway,

3.) 60deg rated upstream overcurrent device versus 90deg cable derates cable to 60deg,

and then evil #4), something like you can undo the derating in #3 in the middle when adjusting the rating of the cable.

The solution seemed to pick a starting cable size and run through the iteration to see if it worked. Silly me, I tried using math. Everyone knows that the NEC has nothing to do with math, except when it does, as stated in Article III, Section ©, Column Q, Row *, line 5, paragraph @, Item (7), word 11.

Good luck to all.

BRING IT ON!

(...oh, it's broughten)

:drunk:

_Wake me up when October ends_


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## Frontier05 (Nov 2, 2006)

> From (fried) memory, the derates in the problem were:
> 1.) Temperature adjustment,
> 
> 2.) Multiple conductor in raceway,
> ...


I'm not sure about the last 2 above. Are you refering to lugs? NEC 110-14© tells you how to use the wiring chart for 60 and 90 degree so it accounts for it ....... hopefully that's the code since I'm going from memory.


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## jdd18vm (Jan 5, 2007)

Hi all,

New guy here. 20+ yrs in elect design and PM. Attempting the PE, Power (and NCBELS willing) long story...but can you tell me more about this Kaplan book and what is the emphasis on? I have almost everything from "the other board", the NCEES Sample exam, some Shcaums etc... just hadnt come across this.

Thanks

John


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## Kipper (Jan 5, 2007)

Kaplan - Electrical and Computer Engineering

This is one link to the book. 

It looks like this.

View attachment 197


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## Frontier05 (Jan 6, 2007)

> Hahahaha. Maybe I should have chosen a different word beside funky. Guess most things funky are not a good thing!
> 
> Looks like Kaplin let some get by: Problem #1.22-1.26
> 
> ...


I'm not sure why Kaplin did this, but just as an update on this problem for new test takers.

#122 says to choose #2 conductor. This is a NEC problem. The NEC states for conductors to be run in parallel, they need to be a conductor size of #1/0 minimum. Obviously #2 is smaller then #1/0 so that is a code violation and ya can't do it.

:watch:


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