Disecting article 300.5(I) of the NEC

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jusme123 said:
... "shall be permitted to be arranged as isolated phase installations" , which imo means each phase, not a group of phases or one particular phase. IMO the code gives you two choices, either group each set (ABCN)(ABCN)of parallel circuit conductors in each conduit, or install them as isolated phase installations (AA)(BB)(CC)(NN)
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I Agree with jusme123. But am willing to learn


A&B in one C&N in another. Iwire & Roger do you use or have you used this method on your installs & why? "Is A isolated from C, is B isolated from N? Yes". Is A isolated from B, is B isolated from N? No What would you name this Isolated Parallels?:?
 
mwm1752 said:
I Agree with jusme123. But am willing to learn


A&B in one C&N in another. Iwire & Roger do you use or have you used this method on your installs & why? "Is A isolated from C, is B isolated from N? Yes". Is A isolated from B, is B isolated from N? No What would you name this Isolated Parallels?:?
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The method of the topic of discussion I have never done but, I have done isolated parallel installations and it makes things much easier to keep conductors the same in length not to mention making terminating in tight wiring compartments easier.

The topic for this conversation seems to be more of a theory / common sense exercise in to "what would be wrong with".

For sake of conversation, considering the two sets of feeders below, they would be basically the same electrically speaking.

IOW's the PVC raceways wold not change things whether two or four are used.

BTW, sorry about the primative drawing:)

Modified_Isolated_phase.JPG


Roger
 

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In the theory world of may never happen -- Phase C draws its full load -- A & B have none -- N carries the full unbalanced load -- being in pipe entraps excessive heat (earth would help dissapate) -- C & N jackets eventually degrade. I have no sensible reasoning (seems to confusing)why I would install this way so I'll leave the common sense part for you. Drawing was fine
 
mwm1752 said:
Phase C draws its full load -- A & B have none -- N carries the full unbalanced load Drawing was fine
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In that scenario C and N would cancel currents the same as if we installed a simple two wire 120 volt circuit or feeder. If the conductors are in close proximity (even in plastic raceways) they will negate EMF issues.

Here's another drawing that would show a single ungrounded conductor and it's associate grounded conductor, they would have the same current flowing in opposite directions.

not_a_neutral.JPG


Roger
 
mwm1752 said:
you answered only half the question
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What is the other half of your question?


If it's why would someone do it, it could be as simple as (1) two wire 120 v circuit and (1) 208 v circuit already in place and run side by side that you want to utilize for a 120/208 v 3 phase circuit.



Roger
 
mwm1752 said:
You must be a politician Roger never quite clear answers -- I'm done
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This is the second time you've been done but, in case you change your mind, come back and ask your questions in a direct maner, I really don't know what you want answered..

In the mean time take the feeders I showed in the drawing, get rid of the PVC raceways and ponder what may go wrong.

And BTW, you never answered my question in post # 25.


Roger
 
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