# Sub panel question



## tranza (Aug 19, 2018)

Hi, im a residential guy from NC, this question have probably been answer here before, i have asked tons of ppl why the neutral and the ground have to be separated in the breaker panel but then they are bounded together at the meter base?, i dont see the logic behind this, they are separed at the panel them tie together at the meter base.


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## telsa (May 22, 2015)

I can't even follow your post.


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## wildleg (Apr 12, 2009)

if the neutral and ground are bonded together in more than one place in a premises, then unwanted current could be flowing on grounded surfaces, pipes, or equipment due to the parallel path now being available by the second (or more) connection, whereas with the one and only one connection allowed by NEC the current on grounding and bonding conductors is supposed to return to the source. This is especially true with something like a subpanel, where an improperly bonded can would definitely allow neutral current to use the grounding conductor as a parallel path back to the main (a violation, and not something you want to have).


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## tranza (Aug 19, 2018)

im sorry, english not my native language,







this is one of my sub panel or what i know as a sub panel. My question is why do i need to separate the ground and neutral cable? if they end up together in the main panel/meter base (in the same lug)


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## joebanana (Dec 21, 2010)

Because at the panel one becomes the grounded conductor, and the other one is the grounding conductor. Same thing, different purposes.


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## eddy current (Feb 28, 2009)

tranza said:


> im sorry, english not my native language,
> 
> 
> 
> ...


If they were not separated, it would be like running parallel neutrals. The current would be running on both. You should not have current running on your ground wires. 

The more important question, are all those branch circuit ground wires terminating on the neutral bar? :surprise: Is that allowed as per the NEC?


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## matt1124 (Aug 23, 2011)

Are you even an electrician? Who are the tons of people you asked, every orange apron in the store?


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## John Valdes (May 17, 2007)

Tranza. Please fill out your profile and tell us a little about yourself.



https://www.electriciantalk.com/f22/announcements/


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## 99cents (Aug 20, 2012)

tranza said:


> im sorry, english not my native language,
> 
> 
> 
> ...


Your post isn't difficult to understand. Telsa's problem, not your's.


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## lighterup (Jun 14, 2013)

Put it this way.

In NM cable the EGC does not have thhn sheathing and the neutral does.
Do you want the return path traveling on a copper conductor that does
not have sheathing on it? The answer should be no. 

The unsheathed copper conductor is for equipment grounding only
and is not intended to be used for the regular return path...

The neutral is sheathed and is carrying the imbalance on the circuit...
(a steady measurable voltage.)

Once it returns on the neutral at the main breaker panel it should
follow POCO's neutral path back through their electrical grid.
If it does not , then POCO has a floating neutral. Because the EGC 
and neutral are bonded together at the main , that return path will
take the path to ground through the ground rods / city water line.

That's not what those are intended for , but that's what will happen.
If that does happen , you don't want that starting down range from 
your main. If you bond the EGC and neutral together down range 
then this could happen .


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## tranza (Aug 19, 2018)

matt1124 said:


> Are you even an electrician? Who are the tons of people you asked, every orange apron in the store?


Why being disrespectful?, i have asked this question to every inspector i have met and none of them have a clear answer.


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## tranza (Aug 19, 2018)

eddy current said:


> The more important question, are all those branch circuit ground wires terminating on the neutral bar? :surprise: Is that allowed as per the NEC?


What do you mean with this?, both bar are separated, one for the ground wires and one for the neutral, they are not bounded.


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## tranza (Aug 19, 2018)

lighterup said:


> Put it this way.
> 
> In NM cable the EGC does not have thhn sheathing and the neutral does.
> Do you want the return path traveling on a copper conductor that does
> ...


Thanks for the answer


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## tranza (Aug 19, 2018)

eddy current said:


> If they were not separated, it would be like running parallel neutrals. The current would be running on both. You should not have current running on your ground wires.


Back to back services have ground and neutral bounded, so in back to back service the remaining current travels in the ground wires too, why is that even allow by NEC?.


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## sbrn33 (Mar 15, 2007)

I have a question also. Why did we have to change the wiring for an outbuilding from 3 wire to 4 wire? Was there really any trouble?


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## macmikeman (Jan 23, 2007)

sbrn33 said:


> I have a question also. Why did we have to change the wiring for an outbuilding from 3 wire to 4 wire? Was there really any trouble?


Don't get Denny upset, the code book allows anyone to present a code change proposal and thereby become one of the members of the Code Club at Mike Holt.
There doesn't have to be reasons, just so long as you can be "in".


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## macmikeman (Jan 23, 2007)

tranza said:


> Hi, im a residential guy from NC, this question have probably been answer here before, i have asked tons of ppl why the neutral and the ground have to be separated in the breaker panel but then they are bounded together at the meter base?, i dont see the logic behind this, they are separed at the panel them tie together at the meter base.



I like this guy already. This reminds me of how Hax used to present many very good electrical questions under many good user names during periods when he was banned. The forum needs these kinds of electrical inquiries to keep the edge of the knife sharpened. The user names were much better though.


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## KnightPower (Nov 5, 2016)

If the two bars are not bonded the only thing I don't see (may be me though).. is the bond from the ground bar to the can. As for the theory this changed sometime back to separate the neutral and ground for what is called "objectionable current" as the others have explained. But it's acceptable to wait and separate the bond at the first means of disconnect. It doesn't have to be at the meter. 250.30 (A)(1).


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## A Little Short (Nov 11, 2010)

KnightPower said:


> If the two bars are not bonded the only thing I don't see (may be me though).. is the bond from the ground bar to the can. As for the theory this changed sometime back to separate the neutral and ground for what is called "objectionable current" as the others have explained. But it's acceptable to wait and separate the bond at the first means of disconnect. It doesn't have to be at the meter. 250.30 (A)(1).



There's nothing to separate at the meter.


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## tranza (Aug 19, 2018)

A Little Short said:


> There's nothing to separate at the meter.


Thats what i mean, we need to separate the neutral and grounding cables at the sub panel (breakers panel) but then the neutral/ground cable end up in the same lug at the main panel (meter base), this make the hole thing bounded again ?, i dont see the logic of separating the ground/neutrals at the breaker panel if they end up bounded in the meter base anyway.

Anyway the answer to this is what @lighterup posted i believe.


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## KnightPower (Nov 5, 2016)

A Little Short said:


> There's nothing to separate at the meter.


Yes I see I mistyped. What I meant is you DON'T have to bond at meter.. not "separate".


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## SISYPHUS (Aug 13, 2018)

sbrn33 said:


> I have a question also. Why did we have to change the wiring for an outbuilding from 3 wire to 4 wire? Was there really any trouble?


Because the old 250.32 only worked *IF* no other return paths existed. 

Time proved that most communication wiring _introduced_ it

And yes, the very same thing happens in our predominant TN-C-S system.


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## SISYPHUS (Aug 13, 2018)

tranza said:


> Why being disrespectful?, i have asked this question to every inspector i have met and none of them have a clear answer.


Then they need to retire, or need a kick in the butt

What is being described is an *MBJ* (Main bonding jumper)

*250.28 Main Bonding Jumper and System Bonding Jumper.*


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## eddy current (Feb 28, 2009)

tranza said:


> What do you mean with this?, both bar are separated, one for the ground wires and one for the neutral, they are not bounded.


First, it’s “bonded” not “bounded”

Second, are you sure they are not connected? Usually they have one on each side for convenience and they are *bonded* together.


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## lighterup (Jun 14, 2013)

eddy current said:


> First, it’s “bonded” not “bounded”
> 
> Second, are you sure they are not connected? Usually they have one on each side for convenience and they are *bonded* together.


In first post , OP sounds like he was talking about the Main.

Then in post #4 he shows a picture of a main lug where the
bonding jumper has been removed .

Note to OP: Bond the casing if you haven't done so yet.
( if you do not know what this means , let us know)


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## tranza (Aug 19, 2018)

lighterup said:


> In first post , OP sounds like he was talking about the Main.
> 
> Then in post #4 he shows a picture of a main lug where the
> bonding jumper has been removed .
> ...


Is already bonded, panel was unfinished at the time i took that picture. That house passed CO inspection already.


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