NM cable through a plastic box.

[fireryan]

Maybe it was installed by the same guy who did this:

​

What in the world

 

[Conduit Phil]

110.12 I would have used a nail-on box

 

[stevenje]

Maybe it was installed by the same guy who did this:

​

Let me guess. The "PULL-THOUGH BOX COUPLING" for the lack of a better term to describe this unique installation, was in an un-accessible location.

 

[Split Bolt]

Let me guess. The "PULL-THOUGH BOX COUPLING" for the lack of a better term to describe this unique installation, was in an un-accessible location.

That's my guess. It was originally run in a space that was going to be accessible. (or so the installer thought) After he found out he screwed-up, he had to make it pass through?!? Who knows? Somebody went through an awful lot of trouble to make this rig! Notice the EMT connectors inside the box are cast and the originals are steel. Is that a Rigid coupling cut in half? It does serve as a VERY fancy EMT strap!

 

[Split Bolt]

That's my guess. It was originally run in a space that was going to be accessible. (or so the installer thought) After he found out he screwed-up, he had to make it pass through?!? Who knows? Somebody went through an awful lot of trouble to make this rig! Notice the EMT connectors inside the box are cast and the originals are steel. Is that a Rigid coupling cut in half? It does serve as a VERY fancy EMT strap!

Just as an afterthought: Should there be a cover on the box?:grin:

 

[Jim W in Tampa]

Only thing you could push is the unused opening needs sealed. Other than that it is stupid but ok

 

[KP2]

I also dont know the exact cu." but the the two conductors count as one each and the ground would not count, well only one would so it should be ok as is for box fill. What I am trying to say is I dont see any violation, but would be interesting to find out for sure.

How would the example be any different than Exhibit 314.1 Handbook?

This is a class project on box fill that one of my students built to stump their classmates. We don't see any code violations, however when counting box fill I feel the ground in the NM cable needs to be counted if it is not connected to the EGC that is in the box.
While we are all aware that the job is bizarre and will not be done in the field the project was to design challenging box fill calculations. {mission accomplished }.
Just like in Exhibit 314.1 count all wires that go straight through the box as one, or think of it as an isolated ground.

What do you guy's think????:-?:-?

 

[Jim W in Tampa]

Grounds count as 1

 

[KP2]

Grounds count as 1

The way I see it, we are talking about Equipment Grounding Conductors. in order for a ground wire to be considered an EGC it must be connected to all EGC's in the box and to the equipment. The ground wire inside the NM is not an EGC and must be counted seperatly.
I understand we say " All grounds count as one", however what we mean is All Equipment Grounding Conductors Count as one.
Do you see my point.???

 

[KP2]

Take a look at this example with a separate ground wire. According to 314.16(B)(5), we count them separately.

Any thoughts???

 

[wireguy8169]

This applies

This applies

314.16 (B)(1)

(B) Box Fill Calculations. The volumes in paragraphs

(1) Conductor Fill. Each conductor that originates outside
the box and terminates or is spliced within the box shall be
counted once, and

each conductor that passes through the
box without splice or termination shall be counted once


So you would count the EGC that passes through the box per this NEC section.

 

[eprice]

...in order for a ground wire to be considered an EGC it must be connected to all EGC's in the box and to the equipment.

I don't think anything in the code says that

The ground wire inside the NM is not an EGC and must be counted seperatly.
I understand we say " All grounds count as one", however what we mean is All Equipment Grounding Conductors Count as one.
Do you see my point.???

The ground in the continuous NM is still an equipment ground even though it isn't grounding equipment at this box. It would presumably ground equipment somewhere else.

 

[wireguy8169]

It has to terminate in the box

It has to terminate in the box

To only be counted once by the largest equipment grounding conductor it must terminate in the box. So, since it passes through it must me counted, I posted the code reference I believe supports this, excellent discussion though.

 

[eprice]

Take a look at this example with a separate ground wire. According to 314.16(B)(5), we count them separately.

Any thoughts???

I think it would be a stretch to say that the equipment ground in the continuous NM in the opening post is there to provide an isolated ground.

 

[eprice]

314.16 (B)(1)

(B) Box Fill Calculations. The volumes in paragraphs

(1) Conductor Fill. Each conductor that originates outside
the box and terminates or is spliced within the box shall be
counted once, and

each conductor that passes through the
box without splice or termination shall be counted once


So you would count the EGC that passes through the box per this NEC section.

314.16 (B)(1) and (5) conflict with one another as to how to do the calculation. Since (1) is general to all conductors and (5) is specific to equipment grounds, I think (5) trumps (1) for the equipment grounds.

 

[wireguy8169]

Just the way I read it

Just the way I read it

Each conductor that originates outside
the box and terminates or is spliced within the box shall be
counted once, and each conductor that passes through the
box without splice or termination shall be counted once.

When I read this I don't see where it designates the use of the conductor i.e. grounded, undgrounded, grounding.

I definitly see where there can be a case made for both, I think I would erre on the side of either putting in a larger box so as not to have to change it later, or checking with the AHJ.

If there is a definitive code reference I would like to know..

 

[eprice]

Each conductor that originates outside
the box and terminates or is spliced within the box shall be
counted once, and each conductor that passes through the
box without splice or termination shall be counted once.

When I read this I don't see where it designates the use of the conductor i.e. grounded, undgrounded, grounding.

I definitly see where there can be a case made for both, I think I would erre on the side of either putting in a larger box so as not to have to change it later, or checking with the AHJ.

If there is a definitive code reference I would like to know..

I agree. 314.16 (B)(1) doesn't specify what type of conductors it is talking about. That is why I said above, that it is general for all conductors. I contend that since (5) is specific to equipment grounds, it trumps (1) when calculating equipment ground fill.

If (5) doesn't trump (1) then most if not all electricians have been doing it wrong for a long time. Suppose we have a box with three NM cable entering. Each of those NM cable have an equipment ground. If (1) applies to equipment grounds, then we have to make 3 conductor allowances for the equipment grounds. Since (5) applies to equipment grounds as well, we have to take one more allowance for a total of 4 conductor allowances for the 3 equipment grounds.

 

[Jim W in Tampa]

We are stuck with what nec says and that is they count as 1. I have no idea why or how they arrived at this. They also rate a device based on wire size and a cheap single pole switch counts for same as a GFCI receptacle.
So if this was a test question i would call the grounds 1
Note it did not say terminate or spliced.

 

[macmikeman]

Take a look at this example with a separate ground wire. According to 314.16(B)(5), we count them separately.

Any thoughts???

Did you run out of good 4" square boxes and end up using that beat up one with the 4 extra ko's removed just to save a trip back to the shop?

By the way, it looks like you forgot one ko seal in the bottom of the box....

Not that it has anything to do with the thread.

 

[KP2]

I think it would be a stretch to say that the equipment ground in the continuous NM in the opening post is there to provide an isolated ground.

I changed my wording later in the thread, I rhetorically mentioned Isolated ::grin:, because in 314.16(B)(5) it states " additional set of equipment grounding conductors ..."

I don't think anything in the code says that


The ground in the continuous NM is still an equipment ground even though it isn't grounding equipment at this box. It would presumably ground equipment somewhere else.

To Quote you literally the EGC inside the NM cable is separate because it doesn't stop at this box and equipment in this box can not be connected to it. Therefore making it a separate set.

In conclusion it must be added to the box fill calculation.