Grouping of parallel conductors

[shockin]

I think I can do this but can't seem to find the code reference.

I have PVC nipples. I am installing 8 parallel sets of conductors.

I would like to group the conductors by "phase" through the nipple.

For example one nipple would have just the "A" phases in it.

On either end of the nipplie is a metal cabinet, but I don't believe that that is a factor. I would run an EGC with each nipple as well

Thanks for the help.

 

[RICK NAPIER]

No it would not be permitted see 310.3(B)(1) and 300.20

 

[PEDRO ESCOVILLA]

doesn't make sense. 300.3 (B) states "all conductors of the same circuit........" and see (B) (1) deals with paralleled circuits. sobasically, the answer is no, run a,b,c, and gec in the same nipple , not as you proposed

 

[charlie b]

With non-metallic raceway, you can run all phase A in one conduit, all phase B in a second conduit, etc., under the exception to 300.3(B)(1). There is a restriction in the cross-reference to 300.20(B), and it deals with the metal cabinet. But you are not talking about conduit, you are talking about nipples, which I take to mean short sections of raceway that connect the conduit to an enclosure. What material is used for the conduit itself?

 

[roger]

As Charlie mentions, if all of the raceways are non metallic you can do what you propose if you meet the requiremnts of 300.20(B), some may take it a step further and require non ferrous locknuts for the connectors.

Roger

 

[Smart $]

... What material is used for the conduit itself?

OP states "PVC nipples".

And, "On either end of the nipplie is a metal cabinet, ..."

There is likely a PVC fitting associated with the connection to the cabinets, except perhaps for the locknut mentioned by Roger. No locknut would be needed if using a PVC box adapter.

 

[pete m.]

Did I miss something?

The exception to 300.3(B)(1) states in part "Conductors installed in nonmetallic raceways run underground"

I suppose my question would be: "Are these "nipples" part of an underground installation?"

Pete

 

[roger]

Did I miss something?

The exception to 300.3(B)(1) states in part "Conductors installed in nonmetallic raceways run underground"

I suppose my question would be: "Are these "nipples" part of an underground installation?"

Pete

Pete, see 300.3(B)(3)

(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).

Roger

 

[shockin]

As I read the posts above I believe I can install the conductors by grouping the pahses together.

To further clarify the senerio that I have.

I will be coming out of the back of a metal CT cabient through a pre-cast wall and into the back of a metal switchboard. The nipples will be Schedule 40 PVC and be approx. 12" long.

As I understand 300.20B I will be reaquired to cut a slot between each of the 4 KO's. It would also be advisable to use a non-ferrous LR.

Does this sound correct.

 

[roger]

As I read the posts above I believe I can install the conductors by grouping the pahses together.

To further clarify the senerio that I have.

I will be coming out of the back of a metal CT cabient through a pre-cast wall and into the back of a metal switchboard. The nipples will be Schedule 40 PVC and be approx. 12" long.

As I understand 300.20B I will be reaquired to cut a slot between each of the 4 KO's. It would also be advisable to use a non-ferrous LR.

Does this sound correct.

IMO, yes it does. I would add that these nipples should be as close as possible to one another.

Roger

 

[RICK NAPIER]

Let me revise my answer. Yes you could do it if you meet the requirements of 300.20(B). I just wasn't sure how you would cut slots between the 8 conduits and maintain structural integrity of the cabinet. Perhaps I am wrong and there won't be 8 conduits or the cabinet will be able to withstand all these holes in it.

 

[shockin]

I just wasn't sure how you would cut slots between the 8 conduits and maintain structural integrity of the cabinet. Perhaps I am wrong and there won't be 8 conduits or the cabinet will be able to withstand all these holes in it.

If I can't combine the phases it would take eight 4" conduits. If I can group the pahses I can do it with four 5" conduits. I don't believe that cutting a slot between the four conduits will impact the overall strength of the boxes.

How wide of a slot do I need. The KO's will be 5", I am picturing a 3/4" Slot. Thoughts?

 

[pete m.]

Pete, see 300.3(B)(3)



Roger

Yep... I missed something... :ashamed1:

Thanks Roger.

Pete

 

[Smart $]

If I can't combine the phases it would take eight 4" conduits. If I can group the pahses I can do it with four 5" conduits. I don't believe that cutting a slot between the four conduits will impact the overall strength of the boxes.

How wide of a slot do I need. The KO's will be 5", I am picturing a 3/4" Slot. Thoughts?

Width not specified. Wider is better. Setting any width on my part would be pure speculation (without doing some research).

One alternative not yet mentioned is to cut out section of cabinet wall big enough for entries and exits, and screw on a piece of aluminum plate with KO's. No slot(s) needed in aluminum plate.

Perhaps better yet would be to install a 12" section of duct with large enough cross sectional area for all the conductors...!!!

 

[PEDRO ESCOVILLA]

doesn't 300-20 (B) deal with " a single condutor", wrong application,imo

 

[don_resqcapt19]

Yep... I missed something... :ashamed1:

Thanks Roger.

Pete

Yes, you missed the same thing as the CMP. I tried to delete the exception you cited, with a proposal a couple of cycles ago, saying that there was no need for the exception as that type of installation is already permitted by the section Roger cited. The CMP did not agree.

 

[pete m.]

Yes, you missed the same thing as the CMP. I tried to delete the exception you cited, with a proposal a couple of cycles ago, saying that there was no need for the exception as that type of installation is already permitted by the section Roger cited. The CMP did not agree.

Don, do you happen to have their response to your proposal? I can certainly see now (thanks to my own ignorance and some help from Roger) the redundancy of the two.

Pete

 

[don_resqcapt19]

3-11 Log #2229 NEC-P03 Final Action: Reject
(300.3(B)(1) Exception)
____________________________________________________________
Submitter: Donald A. Ganiere, Ottawa, IL
Recommendation: Delete the following:
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).
Substantiation: The exception is not required. Such installations are permitted
by 300.3(B)(3) in all locations, not just underground locations.
Panel Meeting Action: Reject
Panel Statement: This exception is necessary to permit installations where
nonmetallic raceways are installed in close proximity with all of Phase A in one
raceway, all of Phase B in another raceway, all of Phase C in another, and all
the grounded conductors in another raceway. Where this is useful is between
underground manholes so the phase conductors can exit the raceways and be
easily racked within the manhole, taking up less space, and making it easier to
do testing and maintenance on the installation. This would not be permissible
without this exception.
Number Eligible to Vote: 13
Ballot Results: Affirmative: 13

 

[pete m.]

I seem to miss the logic of that statement.

Pete