# Parallel Feeds - Wire length?



## 360max (Jun 10, 2011)

NEC states that parallel feeds must be exactly same length. 

...its a stupid requirement, as most installed parallel feeds are not the exact length. If the conduits are run next to each other , wires pulled, and terminated, its fine.

310.4 NEC deals with parallel conductors


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## telsa (May 22, 2015)

quarky2001 said:


> I have a question which I'm sure someone on here can answer.
> 
> I know that with parallel feeds, it's important to match wire lengths, material, insulation, termination method, etc. to ensure that each conductor group can split the current equally.
> 
> ...


You are within the tolerance for field practicality. Don't sweat it.

What blows my mind: WHY are you messing with 750 kCMIL ?

If you're already committed to running parallel conductors, then 750 kCMIL makes NO SENSE.

2 x 250 kCMIL beats 1 x 750 kCMIL every way you pencil it out.


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## 360max (Jun 10, 2011)

quarky2001 said:


> I have a question which I'm sure someone on here can answer.
> 
> I know that with parallel feeds, it's important to match wire lengths, material, insulation, termination method, etc. to ensure that each conductor group can split the current equally.
> 
> ...


short answer is no, the same phases (AAA) have to be identical in every aspect 310.4(B), but seldom are in the real world.


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## PlugsAndLights (Jan 19, 2016)

quarky2001 said:


> What I'm curious about is whether the wire length of one phase needs to match another phase.


The intent of the rule (12-108) is that the load current be divided
equally between all parallel conductors. Matching the lengths of 
different phases is no more necessary in the case of parallel runs
than it is in situations without parallel runs. 
P&L


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## glen1971 (Oct 10, 2012)

telsa said:


> You are within the tolerance for field practicality. Don't sweat it.
> 
> What blows my mind: WHY are you messing with 750 kCMIL ?
> 
> ...


I'm not sure of the cost difference in cable, but I'm guessing that 4 x 3c250 kcmil would be more expensive than 2 x 3c750 kcmil cables, counting the labour.. 

To the OP... Here is the quote from 12-108(3)

In parallel sets, conductors of one phase, polarity, or grounded circuit conductor shall not be required to have the same characteristics as those of another phase, polarity, or grounded circuit conductor.

And from the Handbook...

Subrule (3) requires that all the parallel conductors in the same phase/polarity/line or the grounded circuit have the same characteristics [Subrules (1) and (2)], but the conductors of a different phase/polarity/line or grounded circuit conductors may be different


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## Dash Dingo (Mar 3, 2012)

You don't have to match all lengths. 
Parallel feeds on A phase could all be 5 feet, and feeds on B phase could be 100 feet and C could be 200 feet for example.
Just the wires on the same phase have to be the same length.


Sent from my iPhone using Tapatalk


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## quarky2001 (May 29, 2014)

*Here it is...*

For interest's sake, here's the end result of my Friday morning. Wrestling all those 750's and 350's into a space that small took the drive out of me afterwards, but hey, it's done. Hope the inspector doesn't find a problem with it, haha.

Notice the extra five lugs we had to add?!?


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## Brain John (Jul 15, 2016)

I would have made the box longer with the addition of another box on top (assuming there is room), it appears widening the box was not practical


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## PlugsAndLights (Jan 19, 2016)

quarky2001 said:


> For interest's sake, here's the end result of my Friday morning. Wrestling all those 750's and 350's into a space that small took the drive out of me afterwards, but hey, it's done. Hope the inspector doesn't find a problem with it, haha.
> 
> Notice the extra five lugs we had to add?!?


Job done! :drink: Long weekend! :drink::drink:
P&L


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## MechanicalDVR (Dec 29, 2007)

*Nice Looking Job*



quarky2001 said:


> For interest's sake, here's the end result of my Friday morning. Wrestling all those 750's and 350's into a space that small took the drive out of me afterwards, but hey, it's done. Hope the inspector doesn't find a problem with it, haha.
> 
> Notice the extra five lugs we had to add?!?


It's Miller Time !


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