I'm in disagreement with engineer who is trying to tell me. That you can install one phase of 3-phase 30K volt service in seperated conduits.
A-phase in one 4" B-phase in a seperate 4" and C-phase in another 4"
I'm saying they have to be install in same conduit.
Don't know if the OP scenario is paralleled, but it is not required for parallel installations. In fact, it is only permitted by exception where installed underground: 300.3(B)(1), 300.5(I).That's how we always did parallel conductors. Separate conduits. I was under the impression that it was required? Are we talking parallel? I am asking.
That is exactly what it says. If it didn't permit running conductors of the same circuit in different non-ferrous raceways or cables, there would be no need for the reference to 300.20.I should add that I know many interpret 300.3(B)(3) as permitting conductors of the same circuit to be run in different non-magnetic sheathed cables... but it doesn't really say that.
No, it does not say that. Perhaps that is the intent, I don't know... But I do know the words do not explicitly support such an intent.That is exactly what it says. If it didn't permit running conductors of the same circuit in different non-ferrous raceways or cables, there would be no need for the reference to 300.20.
300.3(B)(1)through (B)(4) are really exceptions to the main part of the rule. There is no need for the exception to (B)(1) as (B)(3) permits the installation covered by the exception.
(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4).
(1) Paralleled Installations. Conductors shall be permitted to be run in parallel in accordance with the provisions of 310.10(H). The requirement to run all circuit conductors within the same raceway, auxiliary gutter, cable tray, trench, cable, or cord shall apply separately to each portion of the paralleled installation, and the equipment grounding conductors shall comply with the provisions of 250.122. Parallel runs in cable tray shall comply with the provisions of 392.10(M).
Exception: Conductors installed in nonmetallic raceways run underground shall be permitted to be arranged as isolated phase installations. The raceways shall be installed in close proximity, and the conductors shall comply with the provisions of 300.20(B).
(2) Grounding and Bonding Conductors. Equipment grounding conductors shall be permitted to be installed outside a raceway or cable assembly where in accordance with the provisions of 250.130(C) for certain existing installations or in accordance with 250.134(B), Exception No. 2, for dc circuits. Equipment bonding conductors shall be permitted to be installed on the outside of raceways in accordance with 250.102(E).
(3) Nonferrous Wiring Methods. Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath, where run in different raceways, auxiliary gutters, cable trays, trenches, cables, or cords, shall comply with the provisions of 300.20(B). Conductors in single-conductor Type MI cable with a nonmagnetic sheath shall comply with the provisions of 332.31. Conductors of single-conductor Type MC cable with a nonmagnetic sheath shall comply with the provisions of 330.31, 330.116, and 300.20(B).
(4) Enclosures. Where an auxiliary gutter runs between a column-width panelboard and a pull box, and the pull box includes neutral terminations, the neutral conductors of circuits supplied from the panelboard shall be permitted to originate in the pull box.
Again we have to agree to disagree. If (B)(3) does not permit this, then there is no reason for (3)(B) to be in the code as it would not do anything.
I am not in total disagreement with you, for I believe the intent to permit circuit conductors in more than one non-ferrous, non-magnetic raceway or cable is a viably safe wiring method. All I am saying is the wording of (B)(3) does not give explicit permission to do so. At best, one has to consider it as inferred by inclusion....
PANEL STATEMENT: While there may be some validity to the submitter's substantiation, there is no technical reason why wiring methods employing a nonferrous outer jacket or sheath should not be permitted to be installed as separate cables where the cables are run in close proximity to each other. Since the nonferrous outer jacket or sheath is nonmagnetic, these cables would permit cancellation of magnetic lines of flux from one cable to another. Care must be used where installing these cables to insure the cables are not separated by any ferrous metal products and obviously where entering a ferrous metal enclosure, they must comply with Section 300-20. Aluminum MC cable and nonmetallic sheathed cable are two cables types that could utilize this method of installation.
This action correlates with the action by CMP-7 on Proposals 7-126 and 7-126a allowing single conductor such as nonferrous MC cable with the same requirements as existed for MI cables where single conductor MC cable is used.
...
Smart,
How does the specific exception in 300.3(B)(1) over rule the blanket permission for isolated phase installations that is in 300.3(B)(3)?
Let it suffice to say the current wording does not exhibit the full extent of intent in some ways, and perhaps redundant in others.I stand by my statement that the exception is not required and the isolated underground installation is permitted by (B)(3), we do however need (B)(1) to permit parallel installations in ferrous wiring methods.
As far as the conductors permitted by (B)(3) passing through ferrous metal that is covered by 300.20(B). I know that that section is intended to apply to the conductors where they enter the enclosure, but I think you can take a broad reading of the first sentence of 300.20(B) and say that it applies to any ferrous metal that surrounds or encircles a conductor.
You are correct that it does not address the proximity of the cables to each other, but the code does not currently address the hazard of high magnetic fields, so is that really a safety hazard, assuming that 300.20(B) is complied with?