Code Questions/Exam Prep Help

[starbright28]

okay - thanks guys. i appreciate it alot.

yeah as far as the orginial post i was fumed, frustrated, all into one when I wrote that post, and decided to just write a pm message instead of showing it to everyone on this thread. i had seen posts where before they can get out of hand, and i thought i would be civil enough to delete it for everyone and just do a PM instead. I also didn't want to offend anyone else, and forgot how much moderator sees.

as far as the next questions - i gotta get back to my worksheets and stuff I don't understand before I ask the next question. its funny how at work with the down time we have right now I'm studying!

Edit: spelling mistakes & re-wording my words. (if that makes sense)

 

[celtic]

as far as the next questions - i gotta get back to my worksheets and stuff I don't understand before I ask the next question.

We're not getting any smarter here...the longer you take, the more we forget

 

[starbright28]

Here's a good one I continue to struggle with (and it's on the test). Motor Calculations.

Here's the question.

What minimum size THW conductors are required for a 30 horsepower, 460 volt, three-phase motor?

The full load current is 40A, as I calculated. So I looked in the code section T430.250.

40(1.25) = 50A

If you look on T310.16 you get a #8.

Now I have a feeling I'm missing a few steps with this calculation, or am I just reading into it too much and they are giving me too much information for this problem?

 

[celtic]

Now I have a feeling I'm missing a few steps with this calculation, or am I just reading into it too much and they are giving me too much information for this problem?

I think you might be reading too much into it...or we are both wrong.


#8 THW 50A @ 75?C

 

[tomP]

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

This is exactly what I've told apprentices over the years when dealing with various journey people.
There are a lot of ideas out there and not all are correct.
Its up to you to determine which you wish to follow.
Never stop asking questions!
It holds true in everything in life.

 

[wire jerk]

Hey I always say No stupid question only stupid answers.

I didn't learn by sitting in the corner. Each day is a new lesson, oh and it would seem clich?.

Good luck

 

[celtic]

I didn't learn by sitting in the corner.

Let's test that....

If I put a $100 in the corner of a round room

 

[starbright28]

i have another question for you to help me out on.

how do you figure out the voltage to ground in the systems (i list below)?

here is a system - 120/240V

If you need more information, I'll try and explain better.

EDIT: Trying to make this visible so I can get help on the answer. Been waiting all day!!!!

 

[starbright28]

I couldn't edit my posts in this tread.

I'll re-phrase my question as posted below. How do you figure out the voltage from your line a to ground, line b to ground in 120v/240v system.

and then how do you figure the same thing out for different voltage systems.

It seems that my posts are not getting the answers lately

 

[celtic]

I'm not sure I understand the question...first thought is use a tester, but I am sure that is not what you are looking for.

 

[starbright28]

The question that I am reading states:
What is the voltage from B to ground in the following systems?
120/240
100/200
240/480
300/600
200/400

That's all the inforamation I was given. If this doesn't seem to fit with anything and just confuses everybody, I'll just drop the question, and continue on with the other studying I should be doing. Thanks

 

[celtic]

Does it give any of the answers - multiple choice?

 

[jeff43222]

It looks to me like they are all referring to single-phase systems. The voltage to ground would be the number to the left of the "/".

 

[celtic]

That's what I was thinking....hoping the answers will yeild a backwards path.

 

[starbright28]

Motor Calculation: Confused

Motor Calculation: Confused

EDIT:
I am not sure if the answer that I had provided is wrong, or if my math was wrong. I checked this with my dad and he said it was 250 kcmil.

SEcond Edit: Deleted post and moved it to a new thread. Since no replies with the two threads I have going anymore decided to see if a brand spanking new one dedicated to the motor calc i have in question would get any replies.