Seperate Circuits Grounds And Neutrals - Electrical - Contractor Talk

Seperate Circuits Grounds And Neutrals

 
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Old 08-10-2007, 08:56 AM   #1
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Seperate Circuits Grounds And Neutrals


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?

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Old 08-10-2007, 09:46 AM   #2
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Re: Seperate Circuits Grounds And Neutrals


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.

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Old 08-10-2007, 05:24 PM   #3
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Re: Seperate Circuits Grounds And Neutrals


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.
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Old 08-10-2007, 07:30 PM   #4
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Re: Seperate Circuits Grounds And Neutrals


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?
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Old 08-10-2007, 07:35 PM   #5
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Re: Seperate Circuits Grounds And Neutrals


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.
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Old 08-10-2007, 07:36 PM   #6
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Re: Seperate Circuits Grounds And Neutrals


Quote:
Originally Posted by 72chevy4x4 View Post
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.
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Old 08-10-2007, 11:02 PM   #7
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Re: Seperate Circuits Grounds And Neutrals


Quote:
Originally Posted by 72chevy4x4 View Post
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.
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Old 08-17-2007, 06:08 PM   #8
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Re: Seperate Circuits Grounds And Neutrals


Quote:
Originally Posted by Speedy Petey View Post
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.
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Old 08-17-2007, 07:12 PM   #9
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Re: Seperate Circuits Grounds And Neutrals


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Originally Posted by RobertWilber View Post
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.
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Old 08-17-2007, 07:17 PM   #10
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Re: Seperate Circuits Grounds And Neutrals


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.
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Old 08-17-2007, 07:35 PM   #11
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Re: Seperate Circuits Grounds And Neutrals


Robert, I posed this question over at Electricantalk. Let's see how it plays out.
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Old 08-27-2007, 06:27 AM   #12
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Re: Seperate Circuits Grounds And Neutrals


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.
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Old 08-27-2007, 03:46 PM   #13
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Re: Seperate Circuits Grounds And Neutrals


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.
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Old 08-27-2007, 07:33 PM   #14
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Re: Seperate Circuits Grounds And Neutrals


At one point in time, every great scientific mind knew for a fact that the earth was flat...
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Old 08-27-2007, 08:11 PM   #15
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Re: Seperate Circuits Grounds And Neutrals


Quote:
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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?
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Old 08-27-2007, 08:19 PM   #16
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Re: Seperate Circuits Grounds And Neutrals


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
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Old 08-27-2007, 09:34 PM   #17
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Re: Seperate Circuits Grounds And Neutrals


Quote:
Originally Posted by Speedy Petey View Post
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."
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Old 08-27-2007, 10:52 PM   #18
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Re: Seperate Circuits Grounds And Neutrals


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.
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Old 08-28-2007, 06:13 AM   #19
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Re: Seperate Circuits Grounds And Neutrals


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?
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Old 08-28-2007, 04:20 PM   #20
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Re: Seperate Circuits Grounds And Neutrals


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.

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