Compact Conductors

[woodski1]

I had a test question on Compact Conductors. I was told that I gave the wrong answer, C.

The question was, Conductors are compressed to______between the strands.
A) reduce the inductive effect
B) reduce the air space
C) reduce the cross section area
D) reduce the capacitive effect

I think the examiner is missing the whole point of why there are compact conductors when insisting the answer is B.

B is how we get C.

What do you think?

 

[infinity]

IMO B is the correct answer. Look at the note at the end of Table C.1(A) for the definition.

 

[quogueelectric]

I am going with B The cross sectional area of the actual conductor is what determines the actual size of the conductor. The cross setion of the cable is being reduced by filling air space with conductor material.

 

[infinity]

Here's the definition from Table C.1(A):

Definition: Compact stranding is the result of a manufacturing process where the standard conductor is
compressed to the extent that the interstices (voids between strand wires) are virtually eliminated.

The interstices, or air spaces, between the strands are reduced or removed.

 

[drbond24]

Without the last three words in the question, I would agree with you. However, when they specifically mention the space between the strands, B is the answer.

 

[woodski1]

Infinity, I've seen the definition as well. It was the only place I could find any reference. It does not answer the question of why the air space is eliminated in the conductor.

I still believe it is to reduce the cross sectional area while still maintaining the same circular mils.

I don't think the answer is in the code, other than in the tables you're allowed a greater number of Compact conductors in a raceway. ie. 29 thhn #6 compact conductors in a 2" Rigid PVC raceway vs. 26 "normal" thhn #6.

I had a problem with raceway fill one time and tried to find compact conductors and my rep at Graybar said he never heard of them. I've only seen it done with service entrance cable.

quogueelectric: An #6 is number #6. It is determined by the copper, not the air.

drbond24: I believe the question is asking why, not how.

I'm going to look in the "American Electrician's Handbook" and if I cann't find the answer to why, I quess it's a question for the manufacturers.

 

[iwire]

I still believe it is to reduce the cross sectional area

Of course your correct, the goal is to reduce the cross section.

BUT, that is not really what the question asks, you are jumping one step ahead.

Lets look at the question again

The question was, Conductors are compressed to______between the strands.
A) reduce the inductive effect
B) reduce the air space
C) reduce the cross section area
D) reduce the capacitive effect

So you answered 'C'.


Conductors are compressed to reduce the cross section area between the strands.

Well to me that just does not fit, we are not reducing the cross section area between the strands.

Now lets try B


Conductors are compressed to reduce the air space between the strands.

Now that works, the key is just what drbond24 pointed out. The words "between the strands" clearly mean the answer is B.