# Outside breaker, inside main breaker panel, so is it a sub?



## CPF (Nov 29, 2011)

Hi everyone! I was doing some work outside my house today, and this thought occurred to me. On the outside of my house, directly below the meter, is a 100amp breaker. There are no smaller breakers or circuits branching off of this box, it just goes directly from there to my 200amp indoor breaker box (which I believe is acceptable even though the outside switch is only 100amp). I've never opened up that outdoor breaker to see how it is wired, but it appears to only have space for that one 100amp breaker, and there isn't any space for any other breakers to ever be added.

*My question is, since I have that first breaker on the outside, is that actually my main, and my inside breaker box is then a sub panel?* There are currently only 3 wires (two insulated, one bare 4 awg copper all jacketed together as SE-U) coming from that outdoor breaker into my indoor breaker box. I was just thinking that maybe that outdoor breaker could be making my indoor breaker box a sub panel, in which case it would really need 4 wires and a split ground and neutral, right?

Hopefully I'm just being paranoid, and the outdoor breaker isn't automatically making my indoor box a sub. I'm looking to sell my house and I want everything to be up to snuff beforehand. 

I really appreciate your thoughts! I'm a rare poster, but a frequent reader!


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## Julius793 (Dec 13, 2011)

1. Where is the grounding electrode conductor connected to?

2. When you say the wire is 4awg copper is the all or just the bare one?


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## plummen (Jan 10, 2010)

Shut off the outside breaker and see if it kills power to your indoor panel,then youll know if its a sub or not


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## CPF (Nov 29, 2011)

1) I apologize if I'm not using the correct terminology, is the "grounding electrode" the copper ground rod? If so, I'm not sure exactly where it is connected, either to the meter socket or that outside box (again, I haven't opened it). It definitely isn't wired to the panel in the house.

2) If I read the jacket of the wire correctly, all 3 are 4awg. I find that to be rather small, but it looked like that might be ok based on a google search of table 310.15(B)(6)?? Please correct me if I'm misunderstanding that!

I should note that I didn't do any of this wiring, it was like that when I bought the place several years ago. I live in a rural community that had absolutely no licensing or inspections until a few years ago, so who knows if anything was ever right!

And yes, this outdoor breaker shuts off the indoor power, that is its sole purpose. So - if that makes the indoor panel a sub panel, how do I fix the issue?


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## plummen (Jan 10, 2010)

Well it sounds like youve basically got a 100a service/disconnect feeding a 200a panel.
Do you have a picture of the inside of the panels,what made you start worrying about them?


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## Julius793 (Dec 13, 2011)

CPF said:


> 1) I apologize if I'm not using the correct terminology, is the "grounding electrode" the copper ground rod? If so, I'm not sure exactly where it is connected, either to the meter socket or that outside box (again, I haven't opened it). It definitely isn't wired to the panel in the house.
> 
> 2) If I read the jacket of the wire correctly, all 3 are 4awg. I find that to be rather small, but it looked like that might be ok based on a google search of table 310.15(B)(6)?? Please correct me if I'm misunderstanding that!
> 
> ...


Indoor panel is a sub and the neutral and ground must be separate 

*edit


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## plummen (Jan 10, 2010)

What kind of wire is it?


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## Julius793 (Dec 13, 2011)

plummen said:


> What kind of wire is it?


Doesn't really make a difference :wink:


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## CPF (Nov 29, 2011)

Well, I'm having trouble sleeping so I just got out of bed and saw your posts. After this one, I'm trying to go back to sleep so don't expect any replies till tomorrow 

Plummen: Nothing really made me worry I guess, I just have done a lot of studying of the electrical forums for a garage subpanel project I've been planning at another property, and I got all the info about separating the ground and neutrals on sub panels. Then today out of the blue, I just happened to think about my house electric and how that indoor panel maybe needs another wire. And sorry, I don't have any pictures, I've never even opened up that outdoor box (I'm a little nervous around power I can't shut off). The indoor panel can be safely shutoff outside, but the outside panel can't be shut off without having someone pull the meter. You wanted to know, it is copper 4awg, it says THHN or THWN SE Style U.

Julius: I'm just trying to learn, I'm not questioning your experience, but why does table 310.15(B)(6) indicate that the 4awg copper is acceptable? What I found was 2008 NEC. Am I not understanding correctly when that table should be used?

Apparently I've got a couple of issues at play here - typical! Thanks for the responses so far!


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## plummen (Jan 10, 2010)

CPF said:


> Well, I'm having trouble sleeping so I just got out of bed and saw your posts. After this one, I'm trying to go back to sleep so don't expect any replies till tomorrow
> 
> Plummen: Nothing really made me worry I guess, I just have done a lot of studying of the electrical forums for a garage subpanel project I've been planning at another property, and I got all the info about separating the ground and neutrals on sub panels. Then today out of the blue, I just happened to think about my house electric and how that indoor panel maybe needs another wire. And sorry, I don't have any pictures, I've never even opened up that outdoor box (I'm a little nervous around power I can't shut off). The indoor panel can be safely shutoff outside, but the outside panel can't be shut off without having someone pull the meter. You wanted to know, it is copper 4awg, it says THHN or THWN SE Style U.
> 
> ...


Thank you,saved me a lot of looking for my book


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## Julius793 (Dec 13, 2011)

CPF said:


> Julius: I'm just trying to learn, I'm not questioning your experience, but why does table 310.15(B)(6) indicate that the 4awg copper is acceptable? What I found was 2008 NEC. Am I not understanding correctly when that table should be used?
> 
> Apparently I've got a couple of issues at play here - typical! Thanks for the responses so far!


*Edit


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## zappa (Nov 25, 2011)

To answer your main question, since it is old work they shouldn't require you to change your bonding scheme to the newer 4 wire.


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## brric (Mar 5, 2010)

Julius793 said:


> Very good question and the answer is like this. Even though thhn is rated for 90 degrees it can't be used for it in most situation. The reason for that is being that the lugs, circuit breakers Ect.. Are only rated for 75 degrees. Therefore you will be limited to the 75 degree column. Now when using romex you will be limited to the 60 degree column.


 #4 Cu is perfectly acceptable for a 100 amp dwelling unit service.


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## Julius793 (Dec 13, 2011)

brric said:


> #4 Cu is perfectly acceptable for a 100 amp dwelling unit service.


I do stand corrected I was using 310.15 (b) (16).


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## md2lgyk (Jan 6, 2009)

Are some of you saying that because I have a meter main, that makes my breaker panel a subpanel? I've never heard that before. My house is only three years old, and I'm pretty sure there aren't four wires feeding the breaker panel. When did that become a requirement? My county was using NEC 2005 when the house was built.


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## zappa (Nov 25, 2011)

md2lgyk said:


> Are some of you saying that because I have a meter main, that makes my breaker panel a subpanel? I've never heard that before. My house is only three years old, and I'm pretty sure there aren't four wires feeding the breaker panel. When did that become a requirement? My county was using NEC 2005 when the house was built.


Yes on the subpanel. I believe it was 2008 but not 100% sure.


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## plummen (Jan 10, 2010)

Yes if your house has an outdoor disconnect before the panel(normally done because of distance between meter and panel)the outdoor disconnect is considered the service mains and your panel is considered a sub panel.
If thats the way the house was wired origionally and signed off by city or cty inspector youve got nothing to worry about


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## Daniel Holzman (Mar 10, 2009)

Part of the trouble attempting to decipher your situation is the unfortunate fact that the term subpanel is NOT USED in NEC, nor is it defined. For an authoritative discussion about what a subpanel is, and how to spell the term, see http://www.ashireporter.org/articles/articles.aspx?id=1649

While this may be simply an awkward fact of life, the primary issue is that almost everyone in the business seems to think that NEC requires that 4 wire service be extended to subpanels, while three wire service is acceptable for the service disconnect. Of course, NEC does not say this, as NEC does not define subpanel, it clearly cannot specify wire configuration for something that does not exist.

Under article 100, the term panelboard is defined. I think it is relatively clear, or at least as clear as anything in NEC, that a single outside breaker is not a panelboard under the meaning of article 100. Article 408.34 classifies panelboards into Lighting and Appliance Branch-Circuit Panelboards and power panelboards.Your primary panelboard is probably a lighting and applicance branch circuit panelboard under NEC (more than 10% of the overcurrent devices protect lighting and applicance circuits). As such, I believe it requires 4 wire service, since it is not service entrance equipment, however I leave it to the professional electricians to weigh in on this confusing matter.


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## md2lgyk (Jan 6, 2009)

plummen said:


> Yes if your house has an outdoor disconnect before the panel(normally done because of distance between meter and panel)the outdoor disconnect is considered the service mains and your panel is considered a sub panel.
> If thats the way the house was wired origionally and signed off by city or cty inspector youve got nothing to worry about


OK, so does that mean I can't put a subpanel in my detached shed and power it from the house's breaker panel?


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## Julius793 (Dec 13, 2011)

md2lgyk said:


> OK, so does that mean I can't put a subpanel in my detached shed and power it from the house's breaker panel?


You can have multiple subs that is not an issue. However being that it's detached it's a little more complex.


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## md2lgyk (Jan 6, 2009)

OK, my house was wired to NEC 2005, which is still the applicable code here. Assuming the service disconnect is 3-wire, is it necessary to run 4 wires to a subpanel in a detached building? If I do, will it hurt anything to connect them all?


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## frenchelectrican (Apr 12, 2006)

md2lgyk said:


> Are some of you saying that because I have a meter main, that makes my breaker panel a subpanel? I've never heard that before. My house is only three years old, and I'm pretty sure there aren't four wires feeding the breaker panel. When did that become a requirement? My county was using NEC 2005 when the house was built.


You will have to take a look at the date of the permit when it was pulled some case if they took a permit before the code actaually changed then they can use the old code verison.



zappa said:


> Yes on the subpanel. I believe it was 2008 but not 100% sure.


For NEC codewise they did change that way back 1999 NEC related to both 3 et 4 conductors and that clear up a bit.



md2lgyk said:


> OK, my house was wired to NEC 2005, which is still the applicable code here. Assuming the service disconnect is 3-wire, is it necessary to run 4 wires to a subpanel in a detached building? If I do, will it hurt anything to connect them all?


If you have main breaker at the main panel that can stay 3 conductors but once you go to subpanels it have to be changed over to 4 conductors ( the neutral et ground have to be sperated ) it don't matter if this building is attached or detached ( there is addtional code related to detached building I will address a second ) 

The reason why changed to 4 conductor to improve the safety of electrique code.

Now for detached building the code requirement will varies a bit depending on how the subpanel will be set up but will required a disconnect switch so a main breaker on subpanel will serve this purpose very easy due you will run into more than 6 throw anyway ( under 6 throw that get iffy depending on the local inspector have to say ) 

Hope that help a bit but if need more question just holler one of us will help ya and by the way Stubbie have a good drawing on it so it don't hurt to ask him if he can posted otherwise search it there are few around are posted in the Electrical section of this fourm.

Merci,
Marc


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## md2lgyk (Jan 6, 2009)

Thanks, but that's clear as mud. I have already buried the conduit and run four conductors. Will it hurt anything to hook them all up? There is no permit or inspection for this.


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## frenchelectrican (Apr 12, 2006)

md2lgyk said:


> Thanks, but that's clear as mud. I have already buried the conduit and run four conductors. Will it hurt anything to hook them all up? There is no permit or inspection for this.


Nope and keep the neutral et ground seperated you may end up buy a ground bussbar for few Euros ( Dollars ) and then you are golden plus sink two ground rods ( if this is a detached building ) 

Merci,
Marc


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## CPF (Nov 29, 2011)

Wow, thanks for all the great responses! So it sounds like as long as I leave it alone, I should be grandfathered in on the 3 wire installation, and the 4awg copper is fine.

Now, just for the sake of learning, if I ever were to ever replace this with 4 wire, I understand how to have the breaker panel set up indoors, with the ground and neutral separated. Also, I understand that in the breaker outside, the neutral would come off the lug it has always come off of. My question is, where would I attach the new ground (the 4th wire) at the outside box? I assume there is a small lug of some kind in that outdoor box that the wire attaches to that goes to the ground rod, so would I splice into that wire somehow? What is the method for this, or am I not giving enough details to answer that question?

Again, thank you for all the great posts. It seems like this question may have helped some others besides me!


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## Stubbie (Jan 7, 2007)

CPF said:


> Wow, thanks for all the great responses! So it sounds like as long as I leave it alone, I should be grandfathered in on the 3 wire installation, and the 4awg copper is fine.
> 
> Now, just for the sake of learning, if I ever were to ever replace this with 4 wire, I understand how to have the breaker panel set up indoors, with the ground and neutral separated. Also, I understand that in the breaker outside, the neutral would come off the lug it has always come off of. My question is, where would I attach the new ground (the 4th wire) at the outside box? I assume there is a small lug of some kind in that outdoor box that the wire attaches to that goes to the ground rod, so would I splice into that wire somehow? What is the method for this, or am I not giving enough details to answer that question?
> 
> Again, thank you for all the great posts. It seems like this question may have helped some others besides me!



Dan Holzman was correct in post 18 .... you need a 4 wire feeder from the service disconnect enclosure outside by the meter to the interior 200 amp panel. The one question that still needs to be answered is was the short length of SEU from service equipment to the interior panel inside metal conduit ? Normally the answer is no but .... maybe it is .. ?

NEC 250.24(A)(5) requires separation of neutral and ground load side of the service equipment unless specifically allowed under exceptions in 250.32 and few other areas in the NEC. In your situation they do not apply you need 4 wires or 3 insulated wires and a listed metal conduit between service equipment and the interior panel.

This graphic from mike holt enterprises pretty much sums up what you need
3 wires from the meter to the service equipment .... 4 wires to the downstream panel or if you prefer sub-panel which is not shown.


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## zappa (Nov 25, 2011)

Thanks Stubbie. I was just getting ready to post a link to that long arse thread about a month ago where you posted all of those really nice diagrams on bonding.


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## Stubbie (Jan 7, 2007)

zappa said:


> Thanks Stubbie. I was just getting ready to post a link to that long arse thread about a month ago where you posted all of those really nice diagrams on bonding.


A good graphic saves paragraphs of typing....


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## CPF (Nov 29, 2011)

No, it wasn't in metal conduit, but that's a good point I hadn't thought of. Thank you for the diagram! 

You have all been great, thanks so much for clearing everything up for me!


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## Stubbie (Jan 7, 2007)

CPF said:


> No, it wasn't in metal conduit, but that's a good point I hadn't thought of. Thank you for the diagram!
> 
> You have all been great, thanks so much for clearing everything up for me!


I wouldn't lose sleep over your installation. I've come across several installs like yours that were signed off by inspectors. Most recently was a manufactured home. In your case the neutral in the SEU is carrying both the systems unbalanced current and will also be the effective ground fault path in the event of a ground fault. There is almost no chance of human contact with any objectionable current in your case as there is no parallel path. That usually only occurs when 4 wires are ran and N/G are not separated at the interior panel.


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