# Neutral Question...



## Bob Badger (Apr 19, 2009)

sparky723 said:


> I have a quick question..
> 
> I am having a brain fart and was wondering where in the NEC is the grounded counductor sizing?
> 
> Someone hook me up,please.



220.61 Feeder or Service Neutral Load.


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## sparky723 (Jul 22, 2008)

*neutral*

I got 220.61....butI will provide more details... I am building a service on a detached building and I am putting in a 200 amp base, so along with the 2/0, what is my neutral size?

The building is empty at this time.

Nothing to gather load info from.


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## Bob Badger (Apr 19, 2009)

sparky723 said:


> I got 220.61....butI will provide more details... I am building a service on a detached building and I am putting in a 200 amp base, so along with the 2/0, what is my neutral size?
> 
> The building is empty at this time.
> 
> Nothing to gather load info from.


The NEC expects you did a load calc when you do a service so with the load calc and 220.61 you can figure out the size of the neutral


By the way, 2/0 sounds small .....


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## sparky723 (Jul 22, 2008)

Bob Badger said:


> The NEC expects you did a load calc when you do a service so with the load calc and 220.61 you can figure out the size of the neutral
> 
> How do you do a load calc. on air? The building is EMPTY.
> 
> By the way, 2/0 sounds small .....


??---310.15 (B)(6) shows 200 amps service to be min. 2/0

Heck, 310.16 even shows it at 195 amps..so either way, I'm good with 2/0.


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## voltz (Jun 2, 2010)

Bob Badger said:


> The NEC expects you did a load calc when you do a service so with the load calc and 220.61 you can figure out the size of the neutral
> 
> 
> By the way, 2/0 sounds small .....


Bob I think he is installing cu


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## Bob Badger (Apr 19, 2009)

sparky723 said:


> I am building a service on a detached building and I am putting in a 200 amp base, so along with the 2/0, what is my neutral size?
> 
> The building is empty at this time.
> 
> Nothing to gather load info from.





Bob Badger said:


> The NEC expects you to do a load calc when you do a service so with the load calc and 220.61 you can figure out the size of the neutral.





sparky723 said:


> How do you do a load calc. on air? The building is EMPTY.


There is no NEC exception for 'EMPTY" buildings, you are still required to do load calculations. Load calculations are done all the time before buildings are even constructed. The requirements and how it is done are all in Artcile 220, I am not going to go every section of 220.

Now if it happens the inspector in your area does not require a load calculation to determine a service size ..... well ...... that happens a lot but you cannot 'legally' reduce the neutral size by just guessing, either do the load calculations as required or run a full size neutral.




Bob Badger said:


> By the way, 2/0 sounds small .....





sparky723 said:


> ??---310.15 (B)(6) shows 200 amps service to be min. 2/0


You told us 



sparky723 said:


> I am building a service on a detached building



Is that detached building a dwelling unit?



> 310.15(B)(6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
> and Feeders. *For individual dwelling units of one family,
> two-family, and multifamily dwellings,* conductors,
> as listed in Table 310.15(B)(6), shall be permitted as
> ...


I suspect you cannot use Table 310.15(B)(6) for the 'detached building'.



> Heck, 310.16 even shows it at 195 amps..so either way, I'm good with 2/0.


Yes 2/0 CU is rated 195 Amps at 90C, you cannot use the 90C rating you are down to at least the 75 C column and if an NM or SE feeder is part of the circuit you are down to the 60 C rating.

2/0 CU at 75C is rated 175 amps limiting the overcurrent protection to 175 amps as 175 amps is a standard size listed in 240.6.



voltz said:


> Bob I think he is installing cu


I assumed that from the start, it is still too small unless it is a dwelling unit.


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## 10492 (Jan 4, 2010)

Bob Badger said:


> either do the load calculations as required or run a full size neutral.


 
There's your answer.

+1


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## kbsparky (Sep 20, 2007)

He stated that the building has no load. Load calculation = -0- Amps.

The minimum size neutral allowable for a 200 Amp service would then be a #4.


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## Dennis Alwon (May 9, 2009)

So here is the catch. As Bob pointed out unless the structure is a dwelling then 310.15(B)(6) does not apply. That being said many inspectors would allow that install. Is it the intent of the code-- I don't know. If you are just pulling the wire from the meter to the panel and they are next to each other go ahead and use 3/0 unless you can get the AHJ's okay. 

In terms of a neutral, you can technically go to a #4 but that would be very short sighted. For a residence I have never had a problem downsizing to 1/0. Of course most homes have many 240v no neutral loads so the calculated load for the grounded conductor is generally much smaller than the ungrounded conductors.

The problem is that if you downsize then the inspector has every right to ask for a load calculation.


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## Bob Badger (Apr 19, 2009)

Dennis Alwon said:


> As Bob pointed out unless the structure is a dwelling then 310.15(B)(6) does not apply. That being said many inspectors would allow that install. Is it the intent of the code-- I don't know.


In my onion the code has been clear on this for many cycles, in 2008 they changed the wording to be very clear.

They should not be allowing the use of T310.15(B)(6) for other than dwelling units no matter how they personally feel about it. 




> In terms of a neutral, you can technically go to a #4 but that would be very short sighted.


Not without load calculations to prove that is large enough.



> The problem is that if you downsize then the inspector has every right to ask for a load calculation.


The inspector has every right to ask for a load calculation even with a full size neutral.


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## Bob Badger (Apr 19, 2009)

kbsparky said:


> He stated that the building has no load. Load calculation = -0- Amps.


You are kidding right?


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## Dennis Alwon (May 9, 2009)

Bob Badger said:


> The inspector has every right to ask for a load calculation even with a full size neutral.


Of course, they always have a right to do that. In a resi setting I have never been asked to do a load calculation on a service however if I installed a #4 grounded conductor on a 200 amp service, I will almost guarantee a request for one.


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## Bob Badger (Apr 19, 2009)

Dennis Alwon said:


> Of course, they always have a right to do that. In a resi setting I have never been asked to do a load calculation on a service however if I installed a #4 grounded conductor on a 200 amp service, I will almost guarantee a request for one.


I have no doubt of that at all, but that is not a code answer. That is a _'we always do it this way'_ answer.


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## Dennis Alwon (May 9, 2009)

kbsparky said:


> He stated that the building has no load. Load calculation = -0- Amps.
> 
> The minimum size neutral allowable for a 200 Amp service would then be a #4.



Interesting- now with no house and the ec is using 310.15(B)(6) then wouldn't you have to figure sabc, laundry at the least. Not sure how you would do square footage.

I am just playing around please don't take this seriously although it may have some merit.


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## sparky723 (Jul 22, 2008)

Wow, this op got a lot of response overnight.

The building is a metal building, like a barn. The HO has stated that in the future there MAY be a washer/dryer and a bed out there. 

This building is located in a rural community where there is no inspector or permits required. I still want it to be done right..

I havent done a load calc. on an empty building before. I felt that by sizing the GC the same as the UGC, then Id be covered...is this not the case?

When Im done Ill take pictures and try to get them on here. 

The poco's pole is about 50' away and its an overhead service.


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## kbsparky (Sep 20, 2007)

sparky723 said:


> I felt that by sizing the GC the same as the UGC, then Id be covered...is this not the case?.....


That would be the case. If you sized the neutral the same as your other conductors, that would cover the worst-case scenario. 

You don't need to make a mountain out of a molehill. :laughing:


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## acrwc10 (Jan 28, 2007)

The issues with this senario can be played different ways. With an empty building you can make the load calcs say what ever you want, the only required outlet is the light outside at the door, and maybe a light inside (building code issue). 200 amp panel is kinda large for that.
But if you want to go the extra mile, put in 3/0 cu or 4/0 al. If you want to down size the neutral going one size smaller would be a safe, because there is no way you will run 200A on only one phase. Without a load calc of some sort I wouldn't go down to 2/0 cu unless you are putting in a 175 main breaker, there are too many possible loads that could be added, like electric heat, that could kick you over 175 amps in a hurry.


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## sparky723 (Jul 22, 2008)

kbsparky said:


> That would be the case. If you sized the neutral the same as your other conductors, that would cover the worst-case scenario.
> 
> You don't need to make a mountain out of a molehill. :laughing:


What do you mean? Im not making any mountain...Im simply asking questions.

I will install a 200a base and panel with 2/0. I dont think his needs require more than 2/0 , but they require more than 175 amps.


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## Dennis Alwon (May 9, 2009)

sparky723 said:


> What do you mean? Im not making any mountain...Im simply asking questions.
> 
> I will install a 200a base and panel with 2/0. I dont think his needs require more than 2/0 , but they require more than 175 amps.


2/0 may not be enough as was pointed out earlier. You cannot use the 90C rating for the final ampacity since breakers etc are only listed for 75C.

Also, Bob's point is that the structure may not be a dwelling so 310.15(B)(6) may not apply. It certainly will not apply since there is no dwelling at this point. Thus 3/0 copper is needed.


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## sparky723 (Jul 22, 2008)

I dont believe there is going to be even a simutaneous load of 175a in the building. So with that said, the 200-2/0 scenario would work. 

I feel that the 200a service with 2/0 was actually overkill on my part.


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## Dennis Alwon (May 9, 2009)

sparky723 said:


> I dont believe there is going to be even a simutaneous load of 175a in the building. So with that said, the 200-2/0 scenario would work.
> 
> I feel that the 200a service with 2/0 was actually overkill on my part.


Sparky the load has nothing to do with it. If you install a 200 amp service and the load is 50 amps , then you still need 3/0 copper unless it is a dwelling. Your scenario does not appear to have a dwelling so at this time 3/0 is needed. 2/0 may be great it is not code, IMO. unless 310.15(B)(6) can be used.


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## Shockdoc (Mar 4, 2010)

3/0-3/0- 1/0 nuff said


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## Bob Badger (Apr 19, 2009)

sparky723 said:


> I dont believe there is going to be even a simutaneous load of 175a in the building. So with that said, the 200-2/0 scenario would work.
> 
> I feel that the 200a service with 2/0 was actually overkill on my part.


Well what you feel will work and what the NEC requires are not the same. :no:


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## kbsparky (Sep 20, 2007)

Just change the main breaker to a 175 Amp. Then you can use the 2/0.


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## Shockdoc (Mar 4, 2010)

sparky723 said:


> What do you mean? Im not making any mountain...Im simply asking questions.
> 
> I will install a 200a base and panel with 2/0. I dont think his needs require more than 2/0 , but they require more than 175 amps.


 Just tape your wires, red, white and blue the entire exposed lengths and say you did it for the glory.:laughing: The inspector won't peel the tape to read the wire size.


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## sparky723 (Jul 22, 2008)

Let it be known that the 2/0 is gone and there is 3/0 installed. Thanks everyone for your help and advice.

Anyone got a generator for sale?


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## acrwc10 (Jan 28, 2007)

sparky723 said:


> Let it be known that the 2/0 is gone and there is 3/0 installed. Thanks everyone for your help and advice.


Copper or Aluminum ? :laughing:


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## sparky723 (Jul 22, 2008)

CU...why the :laughing: face?


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## MDShunk (Jan 7, 2007)

sparky723 said:


> CU...why the :laughing: face?


I think he was trying to see if he could drag this out a little more. :thumbsup:


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## sparky723 (Jul 22, 2008)

oh...ok. I say we kill it.


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## MDShunk (Jan 7, 2007)

Beating a dead horse is somewhat of a past time on this site, you'll find- for better or for worse.


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## sparky723 (Jul 22, 2008)

yea I know...they do it over on MH's forum , too.


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## Magnettica (Jan 23, 2007)

723, haven't you seen all the Scotchkote and j-box map jokes? :batman:


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## acrwc10 (Jan 28, 2007)

MDShunk said:


> Beating a dead horse is somewhat of a past time on this site, you'll find- for better or for worse.


 
I don't know about that, "Beating horses" dead or alive, just sounds wrong. But what ever floats your boat.


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## sparky723 (Jul 22, 2008)

Havent heard any j-box map jokes and whats the joke about Scotchkote?:icon_confused::icon_confused:


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## frenchelectrican (Mar 15, 2007)

sparky723 said:


> Havent heard any j-box map jokes and whats the joke about Scotchkote?:icon_confused::icon_confused:


 
Humm., just sit down and enjoy the ride in the fourm one way or other you will find it we all get it one way or other.

Merci.
Marc 

psst.,, this is not a local item around here.


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## Shorty Circuit (Jun 26, 2010)

sparky723 said:


> Wow, this op got a lot of response overnight.
> 
> The building is a metal building, like a barn. The HO has stated that in the future there MAY be a washer/dryer and a bed out there.
> 
> ...


I'm a little puzzled about this? So in this jurisdiction there is no building department, no fire department, no AHJ? No permits required? No stamped sealed drawings for a plan check? They just let you wing-ding it in the field? Where is this anyway, Zimbabwe? BTW, do they also mount a posse and have public mob lynchings in this place too? :laughing:


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## sparky723 (Jul 22, 2008)

Shorty Circuit said:


> I'm a little puzzled about this? So in this jurisdiction there is no building department, no fire department, no AHJ? No permits required? No stamped sealed drawings for a plan check? They just let you wing-ding it in the field? Where is this anyway, Zimbabwe? BTW, do they also mount a posse and have public mob lynchings in this place too? :laughing:


no.yes.no.no.no.no.Rule.no,they have a p.d.


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## electrictim510 (Sep 9, 2008)

Every time I went smaller than a 3/0 on a 200 amp service (except when I had a really cool inspector that knows my work) I have been asked for a load calc.


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## sparky723 (Jul 22, 2008)

electrictim510 said:


> Every time I went smaller than a 3/0 on a 200 amp service (except when I had a really cool inspector that knows my work) I have been asked for a load calc.


See post #27 

510, you're a little late with advice I dont need, but thanks anyway.


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## electrictim510 (Sep 9, 2008)

sparky723 said:


> See post #27
> 
> 510, you're a little late with advice I dont need, but thanks anyway.


It was more of a general comment, not advice. Wasn't meaning to offend you, 723.


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## doubleoh7 (Dec 5, 2009)

Shorty Circuit said:


> I'm a little puzzled about this? So in this jurisdiction there is no building department, no fire department, no AHJ? No permits required? No stamped sealed drawings for a plan check? They just let you wing-ding it in the field? Where is this anyway, Zimbabwe? BTW, do they also mount a posse and have public mob lynchings in this place too? :laughing:


Most of the United States, if looked at in square miles, has no inspections for electrical work. The only thing I HAD to do to be an electrician is print some business cards.


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## Shorty Circuit (Jun 26, 2010)

electrictim510 said:


> Every time I went smaller than a 3/0 on a 200 amp service (except when I had a really cool inspector that knows my work) I have been asked for a load calc.


:no: You got it backwards. It was the the "cool inspectors" who asked for your load calculations. It was the dodos who didn't. :laughing: Kabooom!:happybday:


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## electrictim510 (Sep 9, 2008)

Shorty Circuit said:


> :no: You got it backwards. It was the the "cool inspectors" who asked for your load calculations. It was the dodos who didn't. :laughing: Kabooom!:happybday:


When you have a reputation for genuinely giving a damn rather than just trying to get the work to pass you get inspectors that take your word for it because of it. If you have been an electrician for any length of time I'm sure you have had inspectors take your word for things here and there. I don't think he is a dodo for not asking I think he is being realistic in not asking for a calc when knowing damn good and well most noone ever gets anywhere near 50% of their upgraded service breaker size.


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## sparky723 (Jul 22, 2008)

electrictim510 said:


> It was more of a general comment, not advice. Wasn't meaning to offend you, 723.


you didnt


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