Code Questions/Exam Prep Help

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starbright28

Senior Member
Location
Minnesota
First - I titled this thread this way to ask questions that I am running across using a study guide to see if I came up with the correct answers, and to also scope out stuff that I am just not able to find. Below is my first question. I'm sure there will be a few more.

I have a question regarding smalle conductor rule. I'm looking in Article 310 for conductors, but not finding anything.

What exactly is the small conductor rule?
 

jshaw

Member
Location
Idaho
NEC 240.4(D) Small Conductors: Unless specifically permitted in 240.4(E) or 240.4(G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum after any correction feactors for ambient temperature and number of conductors have been applied.
 

starbright28

Senior Member
Location
Minnesota
Next Question!

Next Question!

Ahh.. thank you. Here I was thinking ampatcites to determine small size, or something along that lines, and in the total wrong section of the code book.

Next Question I have:

Q: When you have a panel fed with two 600 kcmil conductors per phase, what minimum size main bonding jumper is required?

A: I got 2/0 for copper and 3/0 for AL. But then I got to thinking - is it copper or AL, and now i'm confused if I came up with the right answer.
 
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jshaw

Member
Location
Idaho
It doesn't matter. You can use copper or aluminum. You just have to make sure you size according to the conductor material and size of service entrance conductors that are being used in the installation.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
starbright28 said:
Q: When you have a panel fed with two 600 kcmil conductors per phase, what minimum size main bonding jumper is required?


As Celtic asked you need to know the conductor material in order to answer the question. Are the parallel 600's copper or aluminum?

Parallel 600 kcmil Cu would require a 3/0 Cu jumper.
Parallel 600 kcmil Al would only require a 2/0 Cu jumper.
 

starbright28

Senior Member
Location
Minnesota
infinity said:
As Celtic asked you need to know the conductor material in order to answer the question. Are the parallel 600's copper or aluminum?

Parallel 600 kcmil Cu would require a 3/0 Cu jumper.
Parallel 600 kcmil Al would only require a 2/0 Cu jumper.

And hence why I stated that I got the 2 different answers since I didn't know if the parallel 600's were copper or aluminum. And the question didn't state so, so maybe they wanted to know both ways.

Thanks for the answers/help so far. No new questions as of yet.
 

starbright28

Senior Member
Location
Minnesota
New Question!!!

New Question!!!

As I mentioned before, I probably would be listing many questions with this one thread, in hopes that one would answer, or send me in the right direction.


CAPACITOR CONDUCTORS
Question is as follows: What minimum size THW conductor that is requried to supply a three-phase capacitor with a nameplate of 55 kvars, and 460 volts?

Answer - so far on what I got.
I started out in 460.8 which tells me to use 135% of rated current of capacitor.
So I took 55,000 times 1.35 = 74,250.

Wait, am I supposed to do it this way??
55,000 divided by 460 = 119.57 A
119.56521A times by 1.35 = 161.41303A

Now I'm stuck. Did I just do this calcuation correctly? I have a hard time with these types of problems.
 
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celtic

Senior Member
Location
NJ
infinity said:
As Celtic asked you need to know the conductor material in order to answer the question.

You know what?

It doesn't matter!

It's been so long since I took the test I forgot how to read it:
starbright28 said:
Q: When you have a panel fed with two 600 kcmil conductors per phase, what minimum size main bonding jumper is required?

There will only be one "minimum size".
 

starbright28

Senior Member
Location
Minnesota
New Question

New Question

starbright28 said:
CAPACITOR CONDUCTORS
Question is as follows: What minimum size THW conductor that is requried to supply a three-phase capacitor with a nameplate of 55 kvars, and 460 volts?

Answer - so far on what I got.
I started out in 460.8 which tells me to use 135% of rated current of capacitor.
So I took 55,000 times 1.35 = 74,250.

Wait, am I supposed to do it this way??
55,000 divided by 460 = 119.57 A
119.56521A times by 1.35 = 161.41303A

Now I'm stuck. Did I just do this calcuation correctly? I have a hard time with these types of problems.

Just thought I would put this question back to the top.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
This is from the NEC handbook:

The current corresponding to the kVAr rating of a 3 phase capacitor, Ic, is computed from the following formula:


Ic= kVAr X 1000
1.73 X volts
 

mkbuck

Member
Location
Minnesota
Basic Requirements

Basic Requirements

Amanda,

In regard to your question about the capacitor, you have not considered the fact that you stated it was three-phase!

It would appear you are trying to study examination questions rather than learning the basic code requirements and related technical knowledge that a journeyman electrician is expected to know.

When I see questions such as the ones you are posting, questions that seem very specific, but yet lack complete details, well you wonder where they are coming from.

Don't waste your time trying memorize questions that seem confusing because someone only remember part of the information, or does not recall the complete context. DLI has probably changed the variables of the question anyway.

The proper application of code requirements is dependent upon have all the details and context!

Get some good study material that has clear, consise questions and provides answers that include step-by-step solutions.

It does not seem unreasonable that a licensed journeyman should understand grounding and bonding, overcurrent protection, conductor ampacity, branch circuit calculations, placement of required outlets and switches, etc.

So, if half the individuals taking the Minnesota Examination don't understand the items listed above, or can't sovle for an unknown variable in single-phase or three-phase system, wouldn't know what an ungrounded or grounded conductor was, then I wouldn't be surprised if the passing rate was 50%

MKB
 

starbright28

Senior Member
Location
Minnesota
I just want to say that what you just told me made me very frustrated this morning. I feel you were attacking me, instead of helping me.

If that is the case for specific questions, then I won't post them anymore.
 

iwire

Moderator
Staff member
Location
Massachusetts
starbright28 said:
I just want to say that what you just told me made me very frustrated this morning. I feel you were attacking me, instead of helping me.

If that is the case for specific questions, then I won't post them anymore.

Pay no attention to mkbuck if you don't feel like it, that member does not speak for all of the members.

The thing to keep in mind is this is a public forum and while most times you will get helpful answers you are also likely to get answers you don't want or need.

Ask your questions and take away the helpful answers and filter out the bad. :)
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
starbright28 said:
I just want to say that what you just told me made me very frustrated this morning. I feel you were attacking me, instead of helping me.

If that is the case for specific questions, then I won't post them anymore.


I'm with Bob, don't be turned off by someone's opinion. There are many people here who get a great deal of satisfaction helping people and learning for themselves in the process. I won't speak for anyone else but I am one of those people.

I am curious however as to why you deleted you original response to MKB's post?
 

celtic

Senior Member
Location
NJ
starbright28 said:
If that is the case for specific questions, then I won't post them anymore.

Amanda,
don't let anyone run you off this site or "control" your postings.

Ask what you want, question the responses you get...it keeps US on our toes, too:
celtic said:
It's been so long since I took the test I forgot how to read it

If someone has a problem with what you post, it seems you do not the problem, rather they do!


NEXT QUESTION!
 
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