# Seperate circuits grounds and neutrals



## davidchomes (Jun 22, 2007)

Hello.

If you have more than one circuit going to a switch box do all the grounds of both and all the neutrals of both have to get tied together? Such as there is one 20 amp and one 15 amp circuit in a box together or two seperate 15 amp circuits in a box together. Can you or should you tie each circuits grounds/neutrals together seperately?

Thanks

Dave


----------



## RobertWilber (Mar 5, 2006)

I take it you are talking about plastic boxes. The point is moot in metal boxes.
There is no reason to tie grounds of different circuits together.
It would be a violation to join the neutrals. 
If you had a 20 amp circuit and 15 amp circuit, the 15 amp neutral could be carrying 17 amps - unacceptable. 
... and if one of the neutrals opened upstream towards the panel, the 14 gauge could be carrying 30 amps and more, 45 amps if there were three circuits with 2 open, and so on.


----------



## JohnJ0906 (Jan 7, 2007)

As Robert said, it is a violation to put the grounded circuit conductors (neutrals) of different circuits together.

I splice all Equipment grounding conductors of the same size together. If I have, say, #14 and #12 in the same box, I splice each separately, with the appropriate device tails, and add a #12 jumper between splices. I prefer all metal in that box to be bonded.


----------



## AustinDB (Sep 11, 2006)

what about running two circuits w/ a 12/3-is that up to code? based on the discussion, it sounds not to be so, but I've seen it done. I've observed this done in commercial settings with wires run in electrical conduit where there was one neurtral for two hots-is ok then?


----------



## Speedy Petey (Sep 30, 2003)

All grounds that are spliced or terminated in a box must be tied together.
See 250.148. 
There is even an FPN stating that a separate ground for an IG need not be included in this requirement.


----------



## Speedy Petey (Sep 30, 2003)

72chevy4x4 said:


> what about running two circuits w/ a 12/3-is that up to code? based on the discussion, it sounds not to be so, but I've seen it done. I've observed this done in commercial settings with wires run in electrical conduit where there was one neurtral for two hots-is ok then?


This is a perfectly normal and legal installation.


----------



## Magnettica (Dec 19, 2006)

72chevy4x4 said:


> what about running two circuits w/ a 12/3-is that up to code? based on the discussion, it sounds not to be so, but I've seen it done. I've observed this done in commercial settings with wires run in electrical conduit where there was one neurtral for two hots-is ok then?


That's how the power company delivers it's electrical energy to the end user. There's 3 wires, 2 of them are ungrounded, the other grounded, and this grounded conductor gets bonded to a grounding electrode system at the main disconnect. 12/3 and 14/3 homeruns are the same as this set up but with a fancy equipment grounding conductor.


----------



## RobertWilber (Mar 5, 2006)

Speedy Petey said:


> All grounds that are spliced or terminated in a box must be tied together.
> See 250.148.


That isn't what I read.
"Where circuit conductors are spliced within a box, or terminated on equipment ..... , any equipment grounding conductors ASSOCIATED WITH those circuit conductors shall be joined within the box or to the box with devices suitable for the use ...."
Are you suggesting that if I bring two circuits into a plastic box on two cables of two-conductor cable with ground, and each cable terminates on an individual receptacle device, that this section suggests it is required to join the ground wires and install tails to provide a conductor for grounding the device and yoke?
That is not written anywhere here. Nor do I believe it is intended.
I can see where it says if you feed in and out, that the grounding conductors must be joined [obvious], but nothing about joining grounds from separate circuits.


----------



## Speedy Petey (Sep 30, 2003)

RobertWilber said:


> Are you suggesting that if I bring two circuits into a plastic box on two cables of two-conductor cable with ground, and each cable terminates on an individual receptacle device, that this section suggests it is required to join the ground wires and install tails to provide a conductor for grounding the device and yoke?


I absolutely 100% am.

Robert, I'll admit I can see how you are interpreting it that way, but in my opinion (and most other electrician's) I feel you are dramatically incorrect in this interpretation. 

Basically, it says if a ground wire is spliced or terminated, such as with any form of cable (and as opposed to a continuous unbroken ground in raceways) it must be spliced with any other similar grounds in a box. 
The "associated with" applies to ANY and ALL of the the spliced circuit conductors, again, such as with any form of cable.


----------



## JohnJ0906 (Jan 7, 2007)

Although I don't think this is written as well as it could be, I interpret this the same as Petey. Even if I have 2 dead-end swich legs, I will splice the 2 EGCs together w/ 2 tails.


----------



## Speedy Petey (Sep 30, 2003)

Robert, I posed this question over at Electricantalk. Let's see how it plays out.


----------



## RobertWilber (Mar 5, 2006)

calling a quorum and seeking consensus sounds ok to me, but one hundred erroneous opinions don't make fact or the one correct answer wrong [granting that mine may not be THE correct answer...]
what is the ELECTRICAL reason for joining all the grounds?
none I can see
there is therefore no defense for requiring it. period.
I think I'll ask Mike Holt, who occasionally condescends to entertain an inquiry.


----------



## Speedy Petey (Sep 30, 2003)

First off, I would not call the interpretations of many of our fellow qualified electricians "erroneous".

Second, I think you'll agree that there are MANY things in the code that don't always make sense or have a distinct reason.


----------



## RobertWilber (Mar 5, 2006)

At one point in time, every great scientific mind knew for a fact that the earth was flat...


----------



## Speedy Petey (Sep 30, 2003)

RobertWilber said:


> At one point in time, every great scientific mind knew for a fact that the earth was flat...


So what are you saying? It's not? :blink:


----------



## MSSI (Mar 25, 2006)

I seperate the grounds of different circuits just as you would seperate the neutrals. I never just tie all the neutrals togeather like I often find. If there are 2 seperate lighting circuits in a box there are 2 seperate grounds and 2 seperate neutrals


----------



## RobertWilber (Mar 5, 2006)

Speedy Petey said:


> Second, I think you'll agree that there are MANY things in the code that don't always make sense or have a distinct reason.


actually, I tend to doubt there is anything in the Code that doesn't have a distinct reason.
whether I always agree with the rationale, well ........ let me quote a missive I sent in response to a question I received:
"Sorry you are having such great problems.
A legal, safe wiring system can be relied on because it has been installed in accordance with practices and standards developed and defined over the past hundred years through the cooperative efforts of hundreds of thousands of skilled, experienced electrical workers with the combined practical knowledge of MILLIONS of years of installation experience.
... but I don't think there is anything I can do to alleviate the effect of your actions.
The first sentence in your question verifies that the wiring you have installed does not meet these standards.
The product you have created is unsafe and non-functional. And now you ask advice from someone knowledgeable in the subject as to how to mitigate the damage you have wrought.
The only guidance possible is to recommend that:
1] ... you need to learn the rules and practices for installing electrical wiring, then remove the improper segments of your installation and replace them. At this point it may be possible to help you fix your existing problem, if it doesn't just get resolved during the correction process; or
2] ... you need to hire someone knowledgeable in the field to do the same thing."


----------



## Magnettica (Dec 19, 2006)

Electrically, there is NO REASON to tie all equipment grounds together IF there are two circuits in the same box. At least none that I can think of.


----------



## CE1 (Dec 30, 2005)

How about tying them all together to save 1 wire nut and not to confuse the electrician that opened that box up sometime in the future. What would you think if you opened an electrical box with four NM cables entering it and the grounds were not all tied together? Wouldn’t it appear that maybe the electrician that did the install FORGOT to tie all the grounds together?


----------



## Speedy Petey (Sep 30, 2003)

I think what is getting me is that I have never, EVER, seen the grounds _not_ tied together. Nor have I ever heard anyone have the interpretation that it is not required.

Robert is a GOOD electrician, he has every right to his interpretation. It's just like I said above.


----------



## Sparky Joe (Apr 29, 2006)

The DIY reference I made was simply because the electricians in here have extensive knowledge of AC theory, or more specific; when you tie neutrals together and when tying neutrals becomes a fire hazard.
Though there are people who post regularly in this forum who do not know the basics of electrical theory; hence the reference "the power company brings in only 3 wires and shares the neutral".

Don't let Mickey's extensive time on his hands for drawing pictures and pasting irrelevant code articles confuse you into thinking he is a professional, for some reason, whether some of us like his piping in or not, he has seemed to earn his keep.
As for the mentioned disagreement, I read it more as someone upset with the codes wording on a subject and the quality electrician that Robert is, I would not expect that he is isolating grounds in a box. Then there's Mickey who just likes stirring the $hit(I'm surprised he ditched my avatar)

Perhaps your question should have been worded differently, like; "I saw my electrical sub tying his neutrals together today and I'm not sure if that's allowed" I think that would have brought a more receptive audience.
As for tying the grounds together, I would second guess anyone's electrical prowess that did not.

Oh and if you don't trust your sub then find a new one, and if you don't understand AC theory and no one's over your shoulder to tell you what to do, then stay away from wiring. And don't be one of these; "if the inspector signs it off then it must be okay" kind of guys.


----------



## mickeyco (May 13, 2006)

Sparky Joe said:


> Don't let Mickey's extensive time on his hands for drawing pictures and pasting irrelevant code articles confuse you into thinking he is a professional, for some reason, whether some of us like his piping in or not, he has seemed to earn his keep.
> As for the mentioned disagreement, I read it more as someone upset with the codes wording on a subject and the quality electrician that Robert is, I would not expect that he is isolating grounds in a box. Then there's Mickey who just likes stirring the $hit(I'm surprised he ditched my avatar)
> 
> As for tying the grounds together, I would second guess anyone's electrical prowess that did not.


I thought this thread was dead but now that you brought it to the top again tell us exactly how you would wire this. Don't wory about the time it takes me to draw pictures, I can assure you it's minimal. If it's splicing the two ground conductors together and running a pigtail to each device, explain why it's necessary to meet code or any other purpose other than a redundant, additional ground path:










I didn't bring up the article citation, I just posted it in its entirety. My interpretation, while I think it's poorly written, is that it's about attaching any spliced ground conductors in a metal box (not ones passing through) to the metal box and preserving ground continuity by not relying on a device for continuity. Tell me how or why I'm wrong.


----------



## davidchomes (Jun 22, 2007)

Sparky Joe said:


> Perhaps your question should have been worded differently, like; "I saw my electrical sub tying his neutrals together today and I'm not sure if that's allowed" I think that would have brought a more receptive audience.
> 
> 
> 
> ...


----------



## Sparky Joe (Apr 29, 2006)

Does it not make sense to you that when you ask "should all neutrals be tied together" I would say go to the DIY forum.
I did read everything posted here and think that you should not take the dispute of how ground wires are handled as pertaining to your initial question. I think that the exception under 250.148 explains very well that all grounds should be tied together. It does not directly say so, but the exception clearly states that the exception of not tying grounds together pertains to an isolated ground system.
I apologize to those who have a difficult time understanding, but those of you should realize that the code is not an instruction book, and I feel I deserve an apology from those of you whose only intentions is to add 10 more pages to the code book.


----------



## davidchomes (Jun 22, 2007)

Sparky Joe said:


> Does it not make sense to you that when you ask "should all neutrals be tied together" I would say go to the DIY forum.


Sorry, but not when the question was already answered and explained in detail why not to tie them. I guess I'm just an easy going guy and don't see the need to make someone feel like they are out of line for posting a question in this forum. I guess I need to lighten up and just accept that after reading hundreds of posts that those kinds of things are part of the forum at times. So if my questions get answered in the future then that is awesome! If they don't then that is too bad for me and if i get told to go to the DIY area then thats what I will do. Doesn't seem to do much good to say anything otherwise. I realize this is your guys home and I'm just a visitor so I need to just accept the way things are and appreciate getting my questions answered.


----------

