# Distance to short problem

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

1. ### snowhampy Thread Starter New Member

Sep 25, 2008
4
0
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.

• ###### DSCN0545.jpg
File size:
151.8 KB
Views:
16
Last edited: Sep 25, 2008
2. ### hgmjr Moderator

Jan 28, 2005
9,030
214
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
15,815
283
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
4
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
9,030
214
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
4
0
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.