Distance to short problem

Discussion in 'Homework Help' started by snowhampy, Sep 25, 2008.

  1. snowhampy

    Thread Starter New Member

    Sep 25, 2008
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    I have a problem on my homework that I am unable to figure out the equation for it. I've been searching all over trying to find the correct formula but nothing seems right.

    The question states to find the distance to the short from end A. The wire is #10 copper uncoated stranded. I know the the ohm/KFT is 1.28 and the CM is 10380.

    The first part of the problem states: 2 ohms were measured between black and white wire at end A with black wire shorted (connected) to the white wire at end B.

    The second part says: 0.005 ohms were measured through the short between the black wire and the conduit from end A.

    I've tried solving with multiple formulas but nothing seems to come out right. If anyone could please help me out with this one it would be much appreciated.


    I think I may have figured it out but I'm unsure, it would be nice to know if i did or not.
    L=RA/K do that for A and B and subtract the two

    La= 2(10380)/10.4 La= 1996
    Lb= .5(10380)/10.4 Lb=5
    L=1991ft

    This is the only formula that I can find that would make any sence.
     
    Last edited: Sep 25, 2008
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
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    Can you post a diagram of the problem so that we can clearly see what you you are describing?

    hgmjr
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    Does the conduit have a resistance? Otherwise it seems to be the measured resistance over the resistance/1000 feet X 1000. Easier to say that the resistance per foot = .00128 ohms. .005/.00128 = 3.90625'.
     
  4. snowhampy

    Thread Starter New Member

    Sep 25, 2008
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    0
    The conduit does not have a resistance. 005/.00128 = 3.90625' is one of the formulas I was thinking would be right but then I got confused on what the 2ohms resistance, from (a), would have anything to do with the problem.
     
  5. hgmjr

    Moderator

    Jan 28, 2005
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    You may have noticed that 2 ohms when divided by 2 can be used to determine the overall length of the conduit.

    hgmjr
     
  6. snowhampy

    Thread Starter New Member

    Sep 25, 2008
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    Ha! I'm over thinking again. Thank you very much!
     
  7. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I find myself overthinking problems also from time to time. It is always nice to have another person looking at the problem from a different perspective to help get me back on the right track.

    hgmjr
     
  8. snowhampy

    Thread Starter New Member

    Sep 25, 2008
    4
    0
    I'm definitely learning having another perspective makes a big difference and why never working alone would keep sanity within grasp.
     
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