Parallel conductors

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Ken 6789

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I know it's ideal to run parallel conductors as close as possible, but what is the maximum distance the conductors can be apart. Ex. the conductors must be within 18" or 24" of each other. Is there a code reference to this? Thanks.
 
I'm lookin' at 300.20(A) and I'm thinkin' and I'm lookin' and thinkin' and I see the word "grouped" and I see the wording in (B), I'm thinking that the distance between conductors is an issue because of the magnetic field. . And where the fields overlap between hot and neutral, they cancel each other. . So if the wires are close together but not in physical insulation to insulation contact, I imagine that there is a small portion of the field that isn't canceled.

If that's true then I would think that the distance between the conductors would need to be less than the distance between a conductor and any nearby metal part of any kind.

And if I'm wrong, I'll claim that I wasn't actually wrong, but that you misquoted me :roll:

David
 
I meant how much can each conductor deviate in length? If one is 2' longer than the other, I don't want the shorter one to burn up like a fuse because of the lower resistance. Thanks
 
Ken,
If you have a 20' and a 22' in parallel, the 20' will carry 52.4% of the total current and the 22' will carry 47.6%. If you have two conductors in parallel you divide the longer length by the total length of the two conductors and that will give you the percentage of current for the shorter conductor.
Don
 
Ken 6789 said:
I meant how much can each conductor deviate in length? If one is 2' longer than the other, I don't want the shorter one to burn up like a fuse because of the lower resistance. Thanks
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I get it now. . I was "out in left field". . You said "apart" plus I missed the word "parallel" so I was thinking a hot and a neutral or a 2 hots 240v type situation and I was picturing that you were separating the circuit conductors for some reason, maybe open overhead in air conductors on separate insulators.

But that wasn't it.

Length ?

I don't think the answer is a set length, I think it's a percentage. . In the example used by Don, a 22' conductor is 10% longer than the 20' one. . And a 220' conductor is also 10% longer than a 200' one.

Is 10% the max ? . I don't know. . But the answer should be a percentage.

David
 
don_resqcapt19 said:
If you have two conductors in parallel you divide the longer length by the total length of the two conductors and that will give you the percentage of current for the shorter conductor.
Don
Click to expand...
Don this came up last weekend again. Can you tell me where you got that formula or the reasoning behind it? Still confused why Ohm's law isn't a player here.
 
Chris,
Don this came up last weekend again. Can you tell me where you got that formula or the reasoning behind it? Still confused why Ohm's law isn't a player here.
Click to expand...
It is a current divider circuit and the only thing that makes the current divide is the difference in resistance. The difference in resistance is directly related to the length of the conductors. This method provides an answer that will be very close to the answer you will get if you do all of the math, assuming that the lengths are reasonably close.
If you really want to solve it, there are a number of steps using Ohms law.
1) find resistance of each run
2) find resistance of the runs in parallel
3) find the voltage drop of the parallel runs based on full load
4) use the voltage drop from step 3 with the resistance from step 1 to find the current in each run
 
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