NM-B panel entry question

[RD35]

So I've come a cross a simple little thing that has me scratching my head. Guy has his house panel in his garage. Since he has installed a surface mounted manual transfer switch ahead of the panel, he decided to install the panel on the surface rather than flush (recessed between the studs). He's still at the rough-in stage. So, in order to install all of his romex branch circuits he has removed a 2" knockout from the rear of the panel and installed a PVC box adapter and bushing fitting that opens up into the wall cavity directly behind the panel. As I look at the panel I can look into that wall cavity through that big 2" opening in the rear of the panel. Do any of you see a code violation here. I can't find one...but it sure looks strange to me....never seen it done this way before.

 

[infinity]

Not a code compliant installation. Each cable needs to be in a connector or if the connector is listed for multiple cables that is acceptable also. I don't have the NEC handy but someone will provide the reference.

 

[petersonra]

is there a requirement for a clamp where the NM enters a box? or is the requirement that it be secured within 12 inches of the box.

 

[jap]

is there a requirement for a clamp where the NM enters a box? or is the requirement that it be secured within 12 inches of the box.

That's what I was thinking.

JAP>

 

[ActionDave]

I think it would be legal if the Romex is secured within 12" of the panel.

 

[curt swartz]

How about 312.5(C) and 314.17(B)

 

[winnie]

Yes, this sounds like an 'almost' of something that is specifically permitted, and now you end up scratching your head about what the actual safety difference is.

If you go through a big hole in the top of the panel, and have 18" of PVC conduit (as a sleeve), then you can take a bunch of loose romex and bring it into the panel. There are lots of requirements (eg. fastening the cable near where it enters the sleeve, etc.

If instead you go through a hole in the back of the panel through a short sleeve...not compliant but IMHO very similar.

If you go through a hole in the back of the panel to another box with the cable entering through proper cable clamps? IMHO compliant.

-Jon

 

[RD35]

Thanks for the replies! Article 334 leads me to believe this is okay so long as the cables are attached (stapled) within 12 inches. But 312.5 and 314.17 both talk about properly closing the opening (like, say, with a clamp) and that will not happen here although the wall cavity behind the panel is will not be accessible once the rough-in is complete. Hmmm. Guess the AHJ will have to make that call. I suppose he could do as winnie suggests and install a box in the cavity with knockouts and clamps if it gets dinged. Hmmmm :?

 

[PaulMmn]

Thanks for the replies! Article 334 leads me to believe this is okay so long as the cables are attached (stapled) within 12 inches. But 312.5 and 314.17 both talk about properly closing the opening (like, say, with a clamp) and that will not happen here although the wall cavity behind the panel is will not be accessible once the rough-in is complete. Hmmm. Guess the AHJ will have to make that call. I suppose he could do as winnie suggests and install a box in the cavity with knockouts and clamps if it gets dinged. Hmmmm :?

Get the AHJ to make a decision -before- he starts threading wires through it!!

 

[jap]

Thanks for the replies! Article 334 leads me to believe this is okay so long as the cables are attached (stapled) within 12 inches. But 312.5 and 314.17 both talk about properly closing the opening (like, say, with a clamp) and that will not happen here although the wall cavity behind the panel is will not be accessible once the rough-in is complete. Hmmm. Guess the AHJ will have to make that call. I suppose he could do as winnie suggests and install a box in the cavity with knockouts and clamps if it gets dinged. Hmmmm :?

Does a romex connector actually close an opening?

I think not, and, I hope he doesn't have to resort to installing a box in the cavity with KO"s and clamps recessed behind the panel.

That would be worse than what I'm picturing this as already.

JAP>

 

[Dennis Alwon]

That install is done around here a lot but technical it is a violation. 312 allows a conduit installed at the top of the panel. It must be 18' long minimum and it must not penetrate a structural ceiling & then you can use staples within 12". There is nothing about entering from the back of the panel.

 

[infinity]

A panel enclosure is a cabinet so 312.5 applies. There is nothing in the exception that would permit what is outlined in the OP. Other rules that would apply to NM cable entering plastic boxes with no clamps and secured within 8" of the box do not apply to cabinets.

312.5 Cabinets, Cutout Boxes, and Meter Socket Enclosures.
Conductors entering enclosures within the scope of this article
shall be protected from abrasion and shall comply with
312.5(A) through (C).
(A) Openings to Be Closed. Openings through which
conductors enter shall be closed in an approved manner.
(B) Metal Cabinets, Cutout Boxes, and Meter Socket Enclo‐
sures. Where metal enclosures within the scope of this article
are installed with messenger-supported wiring, open wiring on
insulators, or concealed knob-and-tube wiring, conductors shall
enter through insulating bushings or, in dry locations, through
flexible tubing extending from the last insulating support and
firmly secured to the enclosure.
(C) Cables. Where cable is used, each cable shall be secured
to the cabinet, cutout box, or meter socket enclosure.

 

[Dennis Alwon]

I tried to re write this section but I am not sure if this change in the NEC 2020 was supposed to answer my proposal-- exception 2 is the new part. I can't seem to make heads or tail of how that fits in with 312.5

312.5(C) Cables.

Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure.

Exception No. 1: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met: (1)

Each cable is fastened within 300 mm (12 in.), measured along the sheath, of the outer end of the raceway.
(2)

The raceway extends directly above the enclosure and does not penetrate a structural ceiling.
(3)

A fitting is provided on each end of the raceway to protect the cable(s) from abrasion and the fittings remain accessible after installation.
(4)

The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway.
(5)

The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than 6 mm (1∕ 4 in.).
(6)

The raceway is fastened at its outer end and at other points in accordance with the applicable article.
(7)

Where installed as conduit or tubing, the cable fill does not exceed the amount that would be permitted for complete conduit or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto. Note 2 to the tables in Chapter 9 does not apply to this condition.



Informational Note: See Table 1 in Chapter 9, including Note 9, for allowable cable fill in circular raceways. See 310.15(C)(1) for required ampacity reductions for multiple cables installed in a common raceway.

Exception No. 2: Single conductors and multiconductor cables shall be permitted to enter enclosures in accordance with 392.46(A) or (B).

392.46 Bushed Conduit and Tubing.

A box shall not be required where cables or conductors are installed in bushed conduit and tubing used for support or for protection against physical damage or where conductors or cables transition to a raceway wiring method from the cable tray. Conductors shall be permitted to enter equipment in accordance with 392.46(A) or (B).

392.46(A) Through Bushed Conduit or Tubing.

Individual conductors or multiconductor cables with entirely nonmetallic sheaths shall be permitted to enter enclosures where they are terminated through nonflexible bushed conduit or tubing installed for their protection provided they are secured at the point of transition from the cable tray and the conduit or tubing is sealed at the outer end using an approved means so as to prevent debris from entering the equipment through the conduit or tubing.

392.46(B) Flanged Connections.

Individual conductors or multiconductor cables with entirely nonmetallic sheaths shall be permitted to enter enclosures through openings associated with flanges from cable trays where the cable tray is attached to the flange and the flange is mounted directly to the equipment. The openings shall be made such that the conductors are protected from abrasion and the opening shall be sealed or covered to prevent debris from entering the enclosure through the opening.

Informational Note: One method of preventing debris from entering the enclosure is to seal the outer end of the raceway or the opening with duct seal.

 

[jap]

A panel enclosure is a cabinet so 312.5 applies. There is nothing in the exception that would permit what is outlined in the OP. Other rules that would apply to NM cable entering plastic boxes with no clamps and secured within 8" of the box do not apply to cabinets.

312.5 seems to indicate the cable needs to be secured to the cabinet, but, if that's the last sentence, it doesn't indicate how.

Can the installer zip tie the NM to the back of the Panel or "Cabinet" prior to surface mounting it to the wall and get away with using the 2" chase nipple?

Other than keeping debris out the panel, which I totally agree with, not allowing a bushed opening to serve as the entry into the back of the panel if proper fastening of the cable is made prior to,
just seems silly to me.

JAP>

 

[RD35]

Wow this has been an awesome discussion! Thanks everybody for your replies! I don't often deal much with residential stuff. Usually commercial and industrial design work. Very good information here! Much appreciated!!! Based on what you all have discussed, I'm going to suggest he call the inspectors office and talk it over with them before he lands any of his cables in the panel. Also going to suggest he consider just building a chase floor to ceiling around that panel. It will remove the confusion about compliance and will also give him a surface for his flush panel cover to sit on.

 

[kwired]

Wow this has been an awesome discussion! Thanks everybody for your replies! I don't often deal much with residential stuff. Usually commercial and industrial design work. Very good information here! Much appreciated!!! Based on what you all have discussed, I'm going to suggest he call the inspectors office and talk it over with them before he lands any of his cables in the panel. Also going to suggest he consider just building a chase floor to ceiling around that panel. It will remove the confusion about compliance and will also give him a surface for his flush panel cover to sit on.

Chase or other thing I have done is to use a deep box and mount it so back of it is recessed in the wall, but deep enough box that there is still enough protruding to nipple into a surface mounted panel box. Done this with both NM cable installs as well as MC/AC cable installs. One more similar option is surface mounted box or gutter right up to the ceiling to enter cables into the top and then nipple down to the panel, just make sure not to do this in high enough ceiling that you end up with more than 24 inch nipple or you will need to derate conductors in the nipple.