Ampacity

[Bogiedown170]

Hi, was recently a job and saw a 2 inch PVC pipe about 7” long coming out of top panel. At least 20 circuits passed through PVC of 7 inches into panel. I’m trying to familiarize with NEC and read 310.C.1 Conductor Bundle Adjustment) (Four or more Current Carrying conductors). It states “where four or more current carrying conductors are contained in a raceway that is longer than 24”.
What is the NEC rule for the 7” PVC pipe with 20+ conductors going through it? Appreciate any insight and feedback. Thanks.

 

[acin]

Missed a couple nail plates at top plate

 

[Bogiedown170]

Missed a couple nail plates at top plate

Yes for sure, but does ampacity factor have to take place for the 20+ circuits that are going in through 7 inch pvc?

 

[JGinIndy]

Looks like a violation of 312.5

 

[chrismarcellino]

312.5(c) exception requires a minimum of an 18” pipe, but based on the nail plates I assume this is going to have a wall covering, which would make it non-compliant. Oval cable fill rules apply but derating does not until 24”. Looks overfilled.

 

[Fred B]

This is a violation of 312.5(C)(exception) that would allow use of nonflexable conduit to have NM enter an enclosure, violation on the following accounts:
1) raceway must be atleast 18 inches but not more than 10ft. [7 inches is not 18]
2) panelbox or enclosure is to be surface mount not recessed [ Flushmount is not surface mount]
3) not sure but is raceway sealed or plugged at outer end? 312.5(C) exception (4) [can't see from image but likely not]
4) exception (3) fitting is provided on each end of raceway to prevent abrasion [ no fittings in picture]
5) exception (6) raceway fastened at outer ends and other points per applicable articles [no fasteners]
6) exception contingent on conduit fill restrictions in table1 of chapter 9

 

[don_resqcapt19]

Take a look at the exception to 310.15(A)(2) in the 2017 code or 310.14(A)(2) in the 2020.

 

[david]

What you have is a sleeve less than 24 in’s. derating becomes a non-issue for the length of the sleeve

The clips supporting the NMC would by most deal with the bundling issue. The clips should allow free air movement around the cables

It becomes up to the individual inspector if he will also except those clips as a means of securing the cables verses supporting the cables a they enter the sleeve

I have seen electricians for that reason add a stapling board as a securing method before the cables enter the sleeve

Last sealing the sleeve may need to be addressed when the cable runs are completed

This is not facebook so I’ll leave personal preference to myself

edit: This could be a garage or an unfinished basement so i will make no comment as to the sleeve or panel rather being surface mounted

 

[LarryFine]

Not as a nipple, but that is not a compliant way to enter an enclosure.

 

[chrismarcellino]

To answer your question, you need to treat this as one cable according to note 9 table 1:

“(9) A multiconductor cable of two or more conductors shall be treated as a single conductor for calculating percentage conduit fill area. For cables that have elliptical cross sections, the cross-sectional area calculation shall be based on using the major diameter of the ellipse as a circle diameter.”

and would need duct seal, and as mentioned, arguably securement.

 

[kwired]

Yes for sure, but does ampacity factor have to take place for the 20+ circuits that are going in through 7 inch pvc?

Short enough no adjustment needed, but also violates

Looks like a violation of 312.5

Particularly 312.5(C) exception and all the conditions that go with it.
Needs to be minimum 18 inches, would also need to be a surface mounted enclosure per the details. some other details may or may not be in compliance.

 

[david]

Chapter 9 table one kicks in where installed as a conduit or tubing, would it not have to exceed 24 in (sleeve) since this method is allowed up to 10 ft. for this to be considered installing a conduit or tubbing. The wording seems to indicate there is a point that this method is not subject to chapter 9 table one

 

[Fred B]

Chapter 9 table one kicks in where installed as a conduit or tubing, would it not have to exceed 24 in (sleeve) since this method is allowed up to 10 ft. for this to be considered installing a conduit or tubbing. The wording seems to indicate there is a point that this method is not subject to chapter 9 table one

Not in that this article 312.5(C) specifically makes reference to compliance with chapter 9 table 1, in this particular application.

 

[Dsg319]

Hi, was recently a job and saw a 2 inch PVC pipe about 7” long coming out of top panel. At least 20 circuits passed through PVC of 7 inches into panel. I’m trying to familiarize with NEC and read 310.C.1 Conductor Bundle Adjustment) (Four or more Current Carrying conductors). It states “where four or more current carrying conductors are contained in a raceway that is longer than 24”.
What is the NEC rule for the 7” PVC pipe with 20+ conductors going through it? Appreciate any insight and feedback. Thanks.
View attachment 2555827

Hope this helps. Touches on most everything everybody mentioned.

 

[david]

Not in that this article 312.5(C) specifically makes reference to compliance with chapter 9 table 1, in this particular application.

Agreed

Though uncommon to see the distinction would be other raceways that are not tubbing or conduit being used in this type of application

 

[jap]

As it is right now without the wall covering on, if they screwed through the back of the panel to mount it, and not through the sides, it is a "surface" mount panel.

It's mounted to the "surface" of the plywood.

JAP>

 

[Dennis Alwon]

As it is right now without the wall covering on, if they screwed through the back of the panel to mount it, and not through the sides, it is a "surface" mount panel.

It's mounted to the "surface" of the plywood.

JAP>

I realize you are being facetious but that still would not be compliant

 

[jap]

I just feel this whole stub up thing is over rated.

To put a stub up out of a flush mount panel for future access makes perfect sense, but, for a surface mount panel?

To me, the rules are trying to talk you out of it to begin with anyway.

Once you get into the whole "It must be at least 18" but not more than 10 feet", "It must be a surface mount panel", "It must be sealed and plugged after the fact", "provide a fitting on each end", "make sure and fasten the cables close to where the come out of the raceway" etc....

It a stub up out of a surface mount panel guys, not the space shuttle.

JAP>

 

[wwhitney]

Devil's advocate: As a modification to the pictured installation, which if any of the following methods would comply with 312.5(C) "Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure."

1) Screw a metal backplane to the back of the cabinet, extending up above the top of the conduit stub; this is now part of the cabinet. Secure each cable to the metal backplane.

2) Where the grouped cables emerge from the conduit stub inside the enclosure, wrap them all with a single cable tie with eye, screwed to the back of the enclosure.

3) After the cables emerge from the conduit stub inside the enclosure and fan out, secure them in ones or twos to the back of the enclosure with cable ties with eyes.

4) Find a locknut-type NM clamp listed for securing 20 #14 or #12 NM cables (if it exists). Put the clamp inside the cabinet, screw a female adapter onto it instead of a locknut, and then your short piece of PVC conduit.

Cheers, Wayne

 

[Bogiedown170]

Thank you all for the comments and insight. Very helpful.