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Maximum wires in a 2 1/2" nipple

16K views 29 replies 10 participants last post by  rjniles 
#1 ·
My main service panel is mounted on an exterior wall. I have a 2 1/2" x 10" nipple connected to the back of the panel going through to the interior of a sheetrock wall. I am doing some rewire and adding new circuits. Is there a maximum number of wires allowed in the nipple?
 
#4 · (Edited)
I am seeing 60% fill and no derating here. No?

Chapter 9, T1, Note(4) Where conduit or tubing nipples having a maximum
length not to exceed 600 mm (24 in.) are installed between
boxes, cabinets, and similar enclosures, the
nipples shall be permitted to be filled to 60 percent of
their total cross-sectional area, and 310.15(B)(3)(a) adjustment
factors need not apply to this condition.
 
#11 ·
To figure the 60% you would need to compute the area of the conductors to be installed vs 60% of the cross sectional area of the 2" nipple.

These values are computed for you in the Chapter 9 Tables of the NEC.
 
#19 · (Edited)
My main service panel is mounted on an exterior wall. I have a 2 1/2" x 10" nipple connected to the back of the panel going through to the interior of a sheetrock wal

Eh, I think this could be a problem,


NEC 312.5(C) requires that where cable is used, each cable must be secured to the cabinet, cutout box or meter enclosure. Because installers repeatedly violated this rule and jammed in multiple nonmetallic cables through a large PVC connector, a new requirement was added to the 2002 NEC that appears now in NEC 312.5(C) Exception. This exception permits cables with entirely nonmetallic sheaths to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 18 in. and not more than 10 ft. in length, provided the following conditions are met:

(a) Each cable is fastened within 12 in.—measured along the sheath—of the outer end of the raceway.

(b) The raceway extends directly above the enclosure and does not penetrate a structural ceiling.

(c) A fitting is provided on each end of the raceway to protect the cables from abrasion, and the fittings remain accessible after installation.

(d) The raceway is sealed at the outer end using approved means in order to prevent access to the enclosure through the raceway.

(e) The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than ¼ in.

(f) The raceway is fastened at its outer end and at other points in accordance with the applicable article.

(g) Where installed as conduit or tubing, the allowable cable fill does not exceed that permitted for complete conduit systems by Table 1 of Chapter 9 of the NEC and all applicable notes thereto.

Remember, this exception can be used only with surface-mounted enclosures and using nonflexible raceways.



IMO, the only code compliant way for you to do this install is to have a junction box on the end of that nipple and terminate your wires in that box and use THHN into the panel enclosure.
 
#21 ·
Don't forget note 9 to table1 chapter 9. The OP should check with the local EI and find out if the nipple is acceptable on his area. Where does the OP live?
 
#22 ·
Tucson,AZ. I believe in one phone discussion I had with a plans examiner I mentioned the nipple. What would be the issue with it? I figure it to be the correct way to go to protect the wires going through the brick wall. I should probably consult a local licensed electrician to iron out all the details.
 
#23 ·
elmaur said:
Tucson,AZ. I believe in one phone discussion I had with a plans examiner I mentioned the nipple. What would be the issue with it? I figure it to be the correct way to go to protect the wires going through the brick wall. I should probably consult a local licensed electrician to iron out all the details.
I know in some states out there it is common practice to run all the wired through one large bushing. Here in new jersey it is not acceptable. Consult with a local electrician and get his thoughts on the matter.
 
#29 · (Edited)

I don't understand the question... If your wires are coming through a ceiling chase (by this do you mean like a soffit?) Into an interior (sheet rocked on both sides) wall then how are you running a 24" nipple out the back of the panel into that wall? Most panels anymore are mounted on an exterior wall and are recessed into that wall which leaves very little, if any, space between the back of the panel & the sheetrock on the inside of the exterior wall so how are you attaching a nipple to the back of the panel for one thing? And secondly, how is that nipple then going from the back of the panel into an interior wall? Also, why are you needing to use a nipple at all? Is it for protection for the wires? If so, just use a piece of conduit, 18" to 10' long, secure it in two places (meeting NEC distance requirements for securing conduit or exceeding them if the conduit is shorter than the distance requirements) and don't connect it to the panel, just put the wires into snap in plastic connectors (called Push Snaps or Nu Tech's etc.. two flat, same size NMB/Romex per connector is two 14awg, two 12awg etc.. ) that covers your securing the wires going into the panel requirement, you don't have to seal the ends of the conduit because it doesn't enter an enclosure, and then use a product called StackIts on the studs of the interior wall to secure the Romex there. There's usually 4 slots on each StackIt that you can put two same size NMB/Romex in each slot so if you stagger them you can actually get 16 - 14awg, 12awg, or 10awg wires up each stud or a total of 32 NMB/Romex in each stud bay (that's overkill but it is possible). If you just need the nipple for protection, don't connect it to the panel and then you can also put as many as you can fit inside the conduit in there. Just a thought...
 
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