Problems on NEC code
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Dark Knight
Silent Guardian
Try this thread.
NEC Practice Problems
There is a link at one of the posts where you can download practice problems.
Good luck
NEC Practice Problems
There is a link at one of the posts where you can download practice problems.
Good luck
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Dark Knight
Silent Guardian
Hope you were able to download the material. Let us know if you have questions.That is some help, thank you
The example number 11 " What is the ampacity of a #10 ZW2 conductor in a raceway with 5 current carrying conductors?"
They have an answer of 32 amps.
Does anyone think it's incorrect?
I got 30amps ( see table 310.16 and 240.4D) X 0.8 (see table 310.15.B.2.a) = 24amps
They have an answer of 32 amps.
Does anyone think it's incorrect?
I got 30amps ( see table 310.16 and 240.4D) X 0.8 (see table 310.15.B.2.a) = 24amps
VectrenEng
Member
Is the methodology incorrect? On the utility side, I rarely use the NEC, so I am trying to learn/understand these problems.
cableguy
Has never sniffed a stink bug
Isn't the 30 amp limitation for 240.4D new for 2008, and this set of questions based on 2005? So my 'guess' would be for 2005, the answers are correct, but not for us using 2008.
I agree that it seems incorrect. However, I think the answer should be 30 amps because 240.4D states that the 30 amp limit is applied after correction factors are applied.
Dark Knight
Silent Guardian
Problem 18
Per 2008 NEC code section 430.32(1), for motors with service factor 1.15 or greater
1.25 * 28 = 35A and not 1.4 * 28 = 39.2A as indicated.
Problem 19
Per 2008 NEC code section 430.32(1) for motors with temp rise over 40 deg, all other motors
1.15 * 26 = 29.9 and not 1.3 *26 = 33.8
The NEC does allow the 39.2 A and 33.8 A values, but only if 35 A and 29.9 A are not high enough to prevent the motor from tripping on start up. The problems didn't seem clear what it was asking, but I assumed they meant the 39.2 A and 33.8 A values because problems 16 and 17 already used 35 A and 29.9 A.
Question # 11 states what is the ampacity of a # 10 ZW2 conductor with total 5 current carrying conductor in a raceway. Article 240.4D should be considered to find out the protection of conductor only and should not be considered for ampacity itself.
Answer 32 Amps seems to be correct for ampacity of the condutor.
Dark Knight
Silent Guardian
I know there has been some discussion about the results not being accurate or something like that. But have received some e-mails asking for this material. So here is the link...
NEC Problems
The problems are in that link. Just in case, I worked the problem with the 2005 version of the NEC.
NEC Problems
The problems are in that link. Just in case, I worked the problem with the 2005 version of the NEC.
Dark Knight
Silent Guardian
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