seperate connections or a big wire nut for sharing neutrals

[detelec]

I am running 8 ckts in 3/4 EMT using MWBC. 8 hots and 4 neutrals. My question is does it make a difference if you use a large wire nut and connect all neutrals together, Or make 4 seperate neutral connections with circuits on opposite buses of course. My belief is if you tie all neutrals together under one wirenut at j-boxes you don't have to keep track of what conductor is on
what bus to share neutrals. Am I right? Thanks for any input guys

 

[iwire]

The fact that it would be easier is not part of the decision.

Keep them separate.

If you connect them together you have created a violation of 310.4

 

[emahler]

there is a technical term for that violation, we call it the "Big Blue Scotchlock Theory"

 

[detelec]

I don't understand how 310.4 in 2005 nec applies here.

 

[iwire]

If you tie two or more neutrals coming from the panels neutral bar together you have created parallel neutrals.

That is a violation of 310.4

In my opinion you are also likely to violate the rules in 300.3(B) which in general requires you run all the circuit conductors together in the same raceway or cable.

 

[detelec]

Thanks IWIRE I understand now. I better id everthing and make seperate connections.

 

[roger]

Well you could use 1 conductor sized to carry the full load off all the circuits from one leg.

Example, if your 8 circuits are 20 amps each and are 4 on leg 1 and 4 on leg 2 you could use a #4 for the neutral.

Of course you may get some grief from an inspector or your peers, but hey, it's fun to stir things up.

Roger

 

[don_resqcapt19]

Roger,

Well you could use 1 conductor sized to carry the full load off all the circuits from one leg.

The inspector has more ammo now. Look at this.

(215.4)
______________________________________________________________
Submitter: Donald A. Ganiere, Ottawa, IL
Recommendation: Revise as follows:
215.4 Feeders with Common Neutral.
(A) Feeders with common Neutral Two or three sets of 3-wire feeders or two sets of 4-wire or 5-wire feeders shall be permitted to utilize a common neutral.
(B) In Metal Raceway or Enclosure. Where installed in a metal raceway or other metal enclosure, all conductors of all feeders using a common neutral shall be enclosed within the same raceway or other enclosure as required in 300.20.
Substantiation: There is no code violation in using a common neutral so the specific provision to use one is not required.
Panel Meeting Action: Reject
Panel Statement: The panel disagrees with the submitter?s substantiation.
Section 215.4 (A) is the requirement which limits the number of feeders that may share a common neutral.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12

this color = text to be deleted in my proposal.

 

[dingokangaroo]

there is a technical term for that violation, we call it the "Big Blue Scotchlock Theory"

hey i know that theory...seen it a few times

 

[mdshunk]

there is a technical term for that violation, we call it the "Big Blue Scotchlock Theory"

And the corollary, the "Big Grey Twister Theory"

 

[dingokangaroo]

And the corollary, the "Big Grey Twister Theory"

seen that one too....scary

 

[LarryFine]

. . . corollary . . .

Isn't that an old Toyota model?

 

[mdshunk]

Isn't that an old Toyota model?

Yes, the Toyota Corollary. Preferred ride of math teachers the world over. It's a shame that they replaced it with the hybrid Toyota Trisected Angle. It's much smaller.

 

[Minuteman]

Back in my young buck, new, journeyman days I worked for a "My Big Blue Wirenut" guy. We wired a video rental store and a Dr. office with 3 sets of 208 Y using 9 #12 ungrounded and 1 #8 neutral per conduit feeder. We set a 4 11/16" HR box and dropped off one set and ran the other 2 sets with a #10 neutral. Then another 4 11/16" HR box and dropped off the last set with a #12 neutral.

I have never had anyone else want to do it that way.

 

[hardworkingstiff]

If you tie two or more neutrals coming from the panels neutral bar together you have created parallel neutrals.

That is a violation of 310.4

Understand and agree.

In my opinion you are also likely to violate the rules in 300.3(B) which in general requires you run all the circuit conductors together in the same raceway or cable.

I don't believe I agree here. All of the conductors (as I understand the OP are in the same conduit).

 

[hardworkingstiff]

Roger,
The inspector has more ammo now. Look at this.

Isn't the OP discussing branch circuits instead of Feeders? Would 215 even apply to the branch circuits?

 

[hardworkingstiff]

Back in my young buck, new, journeyman days I worked for a "My Big Blue Wirenut" guy. We wired a video rental store and a Dr. office with 3 sets of 208 Y using 9 #12 ungrounded and 1 #8 neutral per conduit feeder. We set a 4 11/16" HR box and dropped off one set and ran the other 2 sets with a #10 neutral. Then another 4 11/16" HR box and dropped off the last set with a #12 neutral.

I have never had anyone else want to do it that way.

Shouldn't it be

3 sets of 208 Y using 9 #12 ungrounded and 1 #6 neutral per conduit feeder. We set a 4 11/16" HR box and dropped off one set and ran the other 2 sets with a #8 neutral. Then another 4 11/16" HR box and dropped off the last set with a #12 neutral.

My reasoning is the max unbalanced load is three conductors all on the same phase carrying the full load (20-amps each) is 60-amps. #8 is not rated for that, #6 would be needed. When you are down to 2 sets, the max unbalanced load would be 40-amps and #10 would be too small so #8 would be needed there.

 

[steve66]

Roger,
The inspector has more ammo now. Look at this.

this color = text to be deleted in my proposal.

I was assuming these were branch circuits, although the OP doesn't say. I don't think there is any such limit on branch circuits.

 

[don_resqcapt19]

Roger,

Isn't the OP discussing branch circuits instead of Feeders? Would 215 even apply to the branch circuits?

Yes, my proposal applies to feeders, but the way I read the panel comment, they are saying that unless there is a specific rule saying that you can use a common grounded conductor, you can't do that. There are a number of case where the CMPs have said you can't do it unless it is specifically permitted. This is contrary to how the code should work.
Don

 

[roger]

Roger,

Yes, my proposal applies to feeders, but the way I read the panel comment, they are saying that unless there is a specific rule saying that you can use a common grounded conductor, you can't do that. There are a number of case where the CMPs have said you can't do it unless it is specifically permitted. This is contrary to how the code should work.
Don

Don, I agree with you and disagree with any CMP that wants or implies "can't do it unless specifically permitted" as an "intent".

BTW, Your quote wasn't mine, it was Hardworking stiffs.

Roger