Art.312

[rome44]

Understanding NEC Vol. 1. Page 322 states; 312.5(C)Ex. (g) Conductor fill is limited to 60%, wording of the text book.

However, in the N.E.Code book (g) doesn't say that at all. the complete text of (g) is; Where installed as a conduit or tubing, the allowable cable fill does not exceed that permitted for complete conduct or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto.

The way I read this is Chap. 9, Table 1 Note: 4 applies the 60% to nipples not longer than 24inches.

In the Code 312.12(C)Ex. says (in part) raceways not less than 18 inches and not more than 10 ft. in length, (g) says to treat it as a complete raceway not as a nipple.

Fellas, either the book is in error or I'm missing something in my interpretation.

Will someone please expand on the subject. :ashamed1:

 

[Dennis Alwon]

I don't see 312.5(C) saying to consider sleeves 18" as a raceway. It s stating that the sleeve must be 18". IMO the 18" sleeve does not get considered in the 60% unless it is a complete raceway

 

[rome44]

Art. 312

Art. 312

312.12(C)EX. says in part; nonflexible raceways not less than 18" and not more than 10ft. in length, provided all of the following conditions are met: (a) thru (g).

It's (g) I'm having trouble with, because it says in part "cable fill does not exceed that permitted for complete conduit or tubing systems by Table 1 of Chap. 9 and applicable notes thereto.

What I read is I'm to treat the 18" to 10ft. length of raceway as a complete system subject to Table 1 of Chap. 9 and notes.
Mike's book Figure 312-6 g. conductor fill is limited to 60%. The only 60% I see is in Note 4 applicable only to nipples having a maximum length not to exceed 24".

Dennis, I don't know what IMO means, but 60% applies only to sleeves not more than 24" not complete systems.

Also, if treated as a complete system seems to me it is subject to Table 310.15(3)(a). What do you think ? Thanks

 

[infinity]

The question is if using the 18"-120" sleeve is it a complete raceway or not.

 

[Smart $]

The question is if using the 18"-120" sleeve is it a complete raceway or not.

IMO, a conduit or other type of raceway cannot be used as a sleeve and as a raceway. Has to be one or the other.

 

[infinity]

IMO, a conduit or other type of raceway cannot be used as a sleeve and as a raceway. Has to be one or the other.

I agree, so for this type of installation, a piece of conduit sticking out of the top of panel with NM cable stuffed into it, which is it?

 

[Smart $]

I agree, so for this type of installation, a piece of conduit sticking out of the top of penal with NM cable stuffed into it, which is it?

Sleeve.

 

[don_resqcapt19]

The way I read the exception is that there is no fill limit for the sleeve as long as it is not installed as conduit or tubing. If it terminates at the top end in an enclosure, it was installed as conduit or tubing. If it does not terminate in an enclosure it is a sleeve.

 

[infinity]

Sleeve.

The way I read the exception is that there is no fill limit for the sleeve as long as it is not installed as conduit or tubing. If it terminates at the top end in an enclosure, it was installed as conduit or tubing. If it does not terminate in an enclosure it is a sleeve.

My interpretation also.

 

[Dennis Alwon]

IMO, in my opinion---

 

[rome44]

Art 312

Art 312

Thanks guys but I"m not any closer to an answer than before, perhaps what's needed is Mike's book "Understanding the NEC Vol. 1 Figure 312-6 on page 322 look at (g) Conductor fill limited to 60%.


Now look in the Code Book (2011) look up 312.5 Exception (g) read text and compare to Mike's book. There's no mention of 60% limit it refers you to Table 1 Chap. 9 and view it as a complete raceway system. There's a conflict here.

 

[Dennis Alwon]

We don't necessarily all have Mike Holt books. You can post the info but realize that we may not agree with Mike Holt either.

 

[don_resqcapt19]

Thanks guys but I"m not any closer to an answer than before, perhaps what's needed is Mike's book "Understanding the NEC Vol. 1 Figure 312-6 on page 322 look at (g) Conductor fill limited to 60%.


Now look in the Code Book (2011) look up 312.5 Exception (g) read text and compare to Mike's book. There's no mention of 60% limit it refers you to Table 1 Chap. 9 and view it as a complete raceway system. There's a conflict here.

The exception does not say that the installation is a complete raceway system. It says "where installed as conduit or tubing" that the fill rules apply. If you do not terminate the sleeve at an enclosure at the top end, it has not been installed as "conduit or tubing". That makes the sleeve a "section of conduit or tubing used to protect exposed wiring from physical damage". Note 2 to Table 1 in Chapter 9 says that the fill rules do not apply to those sections of conduit or tubing.

The code itself is the actual rule, anything else published in the handbook or Mike's book or anywhere else or posted here is just opinion as to what the actual rule means.

 

[kwired]

The way I read the exception is that there is no fill limit for the sleeve as long as it is not installed as conduit or tubing. If it terminates at the top end in an enclosure, it was installed as conduit or tubing. If it does not terminate in an enclosure it is a sleeve.

We don't necessarily all have Mike Holt books. You can post the info but realize that we may not agree with Mike Holt either.

The exception does not say that the installation is a complete raceway system. It says "where installed as conduit or tubing" that the fill rules apply. If you do not terminate the sleeve at an enclosure at the top end, it has not been installed as "conduit or tubing". That makes the sleeve a "section of conduit or tubing used to protect exposed wiring from physical damage". Note 2 to Table 1 in Chapter 9 says that the fill rules do not apply to those sections of conduit or tubing.

The code itself is the actual rule, anything else published in the handbook or Mike's book or anywhere else or posted here is just opinion as to what the actual rule means.

Don kind of summed up in that last post what I was going to say . The exception G is talking about when the conduit or tubing is installed as a raceway then the usual chapter 9 fill tables apply, otherwise all the other parts of the exception are all about when it is used as a sleeve and not a complete raceway.

And yes, even though MH is well respected by many electrical professionals, all his published material is nothing more than his opinion and not an official representation of the NEC or NFPA. He does spend a lot of time on what he does and is very good at it, but probably has had some things that some will not necessarily agree with also.

 

[Smart $]

... The exception G is talking about when the conduit or tubing is installed as a raceway then the usual chapter 9 fill tables apply, ...

What (g) does is allows one to install a box, trough, or other enclosure at the top end and use cable connectors to meet (a), would be sealed or plugged when cover is installed to meet (d), and the sheath does not have to be removed to meet (e).

As I see it, the only difference even having (g) in there is (e). Otherwise, you'd have to remove the sheath upon entry to the box at top, and bring just the wires down through the raceway. However, the fill would be considerably reduced when using flat cable.

 

[kwired]

What (g) does is allows one to install a box, trough, or other enclosure at the top end and use cable connectors to meet (a), would be sealed or plugged when cover is installed to meet (d), and the sheath does not have to be removed to meet (e).

As I see it, the only difference even having (g) in there is (e). Otherwise, you'd have to remove the sheath upon entry to the box at top, and bring just the wires down through the raceway. However, the fill would be considerably reduced when using flat cable.

Fill is reduced even more if you put an equipment grounding bar in the box and land all the EGC's there:happyyes: