paralleling conductors and EGC

[Electron_Sam78]

When you parallel conductors do you split the EGC and run it with each run? For example a parallel run of 2 sets of 600 kcmil with 800amp fuses. This requires a #1/0 copper EGC from T250.122. This is the minimum size for paralleling so if I wanted to run two paralleled EGCs I'd have to keep them at #1/0 instead of splitting it and running 2 #3s with the 2 sets of 600s. I've heard that you want to run an EGC with all conductors of the circuit due to EM interaction. Is this accurate or would it be fine to run only one EGC with one set of the 600s?

 

[infinity]

Each EGC in each raceway must be sized according to the OCPD listed in 250.122. EGC's smaller than #1/0 can be connected at both ends.

 

[raider1]

Check out 250.122(F).

Chris

 

[Electron_Sam78]

Each EGC in each raceway must be sized according to the OCPD listed in 250.122. EGC's smaller than #1/0 can be connected at both ends.

So the #1/0 limit on paralleling conductors does not apply to EGCs? Can you give a code reference? Not that it matters now that I read 250.122(F). It says ai need to run an EGC with each set and each EGC sized using T250.122. Thanks for the reply :thumbsup:

 

[infinity]

Here's the general rule for parallel conductors. {310.4(A)} You'll see that EGC's are not on the list. EGC's are on the list in 310.4(B) but there is not a size limitation in that section. Also they're referenced in 310.4(E) to be sized according to 250.122.

310.4 Conductors in Parallel.
(A) General. Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, polarity, neutral, or grounded circuit conductor shall be permitted to be connected in parallel (electrically joined at both ends).

Exception No. 1: Conductors in sizes smaller than 1/0 AWG shall be permitted to be run in parallel to supply control power to indicating instruments, contactors, relays, solenoids, and similar control devices, or for frequencies of 360 Hz and higher, provided all of the following apply:
(a) They are contained within the same raceway or cable.
(b) The ampacity of each individual conductor is sufficient to carry the entire load current shared by the parallel conductors.
(c) The overcurrent protection is such that the ampacity of each individual conductor will not be exceeded if one or more of the parallel conductors become inadvertently disconnected.
Exception No. 2: Under engineering supervision, grounded neutral conductors in sizes 2 AWG and larger shall be permitted to be run in parallel for existing installations.
FPN to Exception No. 2: Exception No. 2 can be used to alleviate overheating of neutral conductors in existing installations due to high content of triplen harmonic currents.
(B) Conductor Characteristics. The paralleled conductors in each phase, polarity, neutral, grounded circuit conductor, or equipment grounding conductor shall comply with all of the following:
(1) Be the same length
(2) Have the same conductor material
(3) Be the same size in circular mil area
(4) Have the same insulation type
(5) Be terminated in the same manner
(C) Separate Cables or Raceways. Where run in separate cables or raceways, the cables or raceways with conductors shall have the same number of conductors and shall have the same electrical characteristics. Conductors of one phase, polarity, neutral, grounded circuit conductor, or equipment grounding conductor shall not be required to have the same physical characteristics as those of another phase, polarity, neutral, grounded circuit conductor, or equipment grounding conductor to achieve balance.

(D) Ampacity Adjustment. Conductors installed in parallel shall comply with the provisions of 310.15(B)(2)(a).
(E) Equipment Grounding Conductors. Where parallel equipment grounding conductors are used, they shall be sized in accordance with 250.122. Sectioned equipment grounding conductors smaller than 1/0 AWG shall be permitted in multiconductor cables in accordance with 310.13, provided the combined circular mil area in each cable complies with 250.122.

 

[Electron_Sam78]

Here's the general rule for parallel conductors. {310.4(A)} You'll see that EGC's are not on the list. EGC's are on the list in 310.4(B) but there is not a size limitation in that section. Also they're referenced in 310.4(E) to be sized according to 250.122.
...

(E) Equipment Grounding Conductors. Where parallel equipment grounding conductors are used, they shall be sized in accordance with 250.122. Sectioned equipment grounding conductors smaller than 1/0 AWG shall be permitted in multiconductor cables in accordance with 310.13, provided the combined circular mil area in each cable complies with 250.122.

Notice the highlighted part of (E). Why does it say that about EGCs if they're already allowed to be paralleled if smaller than 1/0 AWG?

 

[tkb]

Notice the highlighted part of (E). Why does it say that about EGCs if they're already allowed to be paralleled if smaller than 1/0 AWG?

What they are refering to is when an EGC in a multiconductor cable is sectioned, as in SE cable or bus drop cable.
In conduit you will not be using a sectioned EGC.

1/0 happens to be the smallest paralled conductor and it happes to be the size of the EGC that you need in EACH conduit of your parallel run for 800 amps.

If you were paralleling a 300 amp feeder you would be allowed to parallel #4cu for a EGC and 1/0 for the feeders.

 

[Electron_Sam78]

What they are refering to is when an EGC in a multiconductor cable is sectioned, as in SE cable or bus drop cable.
In conduit you will not be using a sectioned EGC.

1/0 happens to be the smallest paralled conductor and it happes to be the size of the EGC that you need in EACH conduit of your parallel run for 800 amps.

If you were paralleling a 300 amp feeder you would be allowed to parallel #4cu for a EGC and 1/0 for the feeders.

I got all that but what I am curious about now is if it's already allowed by the code to parallel EGCs smaller than 1/0 why would they even put that part in (E) about it being ok to do if it's inside a sectioned cable? Also by the wording of (E) it seems to be indicating that it is not otherwise permitted to parallel EGCs smaller than 1/0 which would contradict the permissiveness of section (A) by the omission of the term "equipment grounding conductor".
:?

 

[jumper]

Here is the ROP:

_______________________________________________________________
5-285 Log #1645 NEC-P05 Final Action: Accept
(250.122(A))
_______________________________________________________________
Submitter: James M. Daly, Upper Saddle River, NJ
Recommendation: Add a second paragraph:
?Equipment grounding conductors shall be permitted to be sectioned within a
multiconductor cable, provided the combined circular mil area complies with
Table 250.122.?
Substantiation: Addition of this additional paragraph will correlate with
310.13 and the multiconductor cable product standards and is more
appropriately located in 250.122. A single equipment grounding conductor
frequently will not fit in the interstice between the insulated conductors in a
multiconductor cable and is required to be sectioned for manufacturing
purposes. The product standards already permit sectioned conductors.
The use of a positive code rule rather than an exception is in accordance with
3.1.4 of the NEC Style Manual.
Panel Meeting Action: Accept
Number Eligible to Vote: 16
Ballot Results: Affirmative: 16
_______________________________________________________________