# Grounding Large Junction Boxes



## TGGT (Oct 28, 2012)

If you have a junction box with several runs, some of which are spliced, and other that are "pass-through" with their own grounds, does every grounding wire that passes through that box need to be broken and spliced?

I read 314.4 which was relatively vague, and 314.40 (D) which also was not specific.


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## tkb (Jan 21, 2009)

250.148


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## TGGT (Oct 28, 2012)

So basically, if you have 8 conduits coming from a box and you splice 1 of those circuits, the grounds in all the other conduits then need to be broken and grounded to the box?

"any equipment grounding conductor(s) associated with those circuits conductors shall be connected within the box"


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## wendon (Sep 27, 2010)

TGGT said:


> So basically, if you have 8 conduits coming from a box and you splice 1 of those circuits, the grounds in all the other conduits then need to be broken and grounded to the box?
> 
> "any equipment grounding conductor(s) associated with those circuits conductors shall be connected within the box"


I think it's speaking of the circuit conductors that are spliced. I might be wrong but I'd say you only need to connect the grounding conductor associated with the conductors that you spliced.


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## 360max (Jun 10, 2011)

read where it states, '...any equipment grounding conductor(s) associated with *those* circuit conductors...'.

* 'Those'* is the key word to zone in on, it refers to the conductors that are spliced.


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## TGGT (Oct 28, 2012)

That's what I thought, but I got in a dispute over it with a guy at work.

I'm sure extra grounding doesn't hurt, but it sure makes a difference as far as production is concerned.


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## icefalkon (Dec 16, 2007)

Yup, I agree with Wendon and 360, it's only the broken/spliced conductors that are associated with the circuit. Only that relative ground needs to be spliced as well.


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## Adam12 (May 28, 2008)

If your coworker won't buy the wording, here's a photo he can't argue with. Make him buy you lunch for teaching him something.


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## wireman64 (Feb 2, 2012)

Adam12 said:


> If your coworker won't buy the wording, here's a photo he can't argue with. Make him buy you lunch for teaching him something.



Stupid question .............… never mind


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## Speedskater (Oct 2, 2009)

What about "Isolated Ground" circuits?


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## Adam12 (May 28, 2008)

Speedskater said:


> What about "Isolated Ground" circuits?


You don't terminate isolated grounds to the box.


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## Dennis Alwon (May 9, 2009)

Be careful here as the metal box needs to be bonded by the largest egc that enters the box. I don't believe you can #6 egc pass thru and have a #12 connected to the box because if the #6 egc circuit shorts to the box it could need the impedance of the #6 not #12 to clear the fault


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## Dennis Alwon (May 9, 2009)

BTW I am assuming plastic conduit. With metal conduit then there may not be a need for the larger egc to be used if it is not spliced


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## Speedskater (Oct 2, 2009)

Adam12 said:


> You don't terminate isolated grounds to the box.


Of course!

But if I were to run two (or more) isolated ground circuits through a J box would I also have to run a Plan-Jane EGC for each IG circuit or can they (the outlet & J boxes share a EGC?


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## Dennis Alwon (May 9, 2009)

Speedskater said:


> Of course!
> 
> But if I were to run two (or more) isolated ground circuits through a J box would I also have to run a plane-jane EGC for each IG circuit or can they (the outlet & J boxes share a EGC?


If you are running metal conduit then the conuit can be the egc and the insulated egc would be for the isolated ground. They cannot be connected together except at the main panel.


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## D-Bo (Apr 15, 2012)

Dennis Alwon said:


> If you are running metal conduit then the conuit can be the egc and the insulated egc would be for the isolated ground. They cannot be connected together except at the main panel.


Is there a specific code reference for this or is it mostly implied? I've had one inspector ask me to break a ground in a pull box to bond it. Seemed pointless to me to do that in a perfectly good all metal conduit system


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## Elephante (Nov 16, 2011)

Adam12 said:


> If your coworker won't buy the wording, here's a photo he can't argue with. Make him buy you lunch for teaching him something.
> 
> View attachment 19149


What if none of the circuits are terminated and spliced and the splice box is PVC with metal conduit, do you have to ground it?If so, what article does that fall under?


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## Adam12 (May 28, 2008)

Elephante said:


> What if none of the circuits are terminated and spliced and the splice box is PVC with metal conduit, do you have to ground it?If so, what article does that fall under?


Are you seriously asking about terminating a EGC to a plastic box?


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## chicken steve (Mar 22, 2011)

they do come with a big 'ol grounding terminal.....~CS~


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## Elephante (Nov 16, 2011)

Adam12 said:


> Are you seriously asking about terminating a EGC to a plastic box?


Do you need grounding bushing if the splice box is PVC?


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## chicken steve (Mar 22, 2011)

D-Bo said:


> Is there a specific code reference for this or is it mostly implied? I've had one inspector ask me to break a ground in a pull box to bond it. Seemed pointless to me to do that in a perfectly good all metal conduit system


HB commentary after 250.148 claims we are allowed to treat it as an L or T.....~CS~


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## 360max (Jun 10, 2011)

Dennis Alwon said:


> Be careful here as the metal box needs to be bonded by the largest egc that enters the box. I don't believe you can #6 egc pass thru and have a #12 connected to the box because if the #6 egc circuit shorts to the box it could need the impedance of the #6 not #12 to clear the fault


...so what if the #6 passes through the box with all conductors and a short occurs?

edit; just read your comment about the conduits, thats were I was going with the question


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## chicken steve (Mar 22, 2011)

either you have a single. or dual fault path 360....~CS~


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## Adam12 (May 28, 2008)

Elephante said:


> Do you need grounding bushing if the splice box is PVC?


If you were going in and out of the PVC box with a metallic raceway I'd use bond bushings to bond the conduits together.


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## Adam12 (May 28, 2008)

d-bo said:


> is there a specific code reference for this or is it mostly implied? I've had one inspector ask me to break a ground in a pull box to bond it. Seemed pointless to me to do that in a perfectly good all metal conduit system


250.92 b 2&3
250.118 2,3,4 & 5


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