Branch circuits entering panel

[bigjohn67]

2 things Id like advise on with Code references.

No. 1
MLO panel mounted in the interior of house, main outside. Does all the MNB's have to be placed in RX connectors and if so what is the max. # of wires per connector? 12/2 rx

Why cant I just use a 2" Male adapter in the top of the panel to bring the wires into the panel?

No. 2
Panel mounted on outside of house. Nipple is permitted with bushing to bring Rx into panel thru the back. If this is allowed by code, why is answer to NO.1 above is that I cant use this same method, why is it allowed outside.

Just asking yall opinion. We use Rx connectors when the panel is on the interior ( because supervisor says we have to, says because of fire hazard to use 2" pvc adapter), but he allows us to use them on exterior panels.

 

[hurk27]

Re: Branch circuits entering panel

I think the only thing in the NEC is when the panel is surface mounted It seems to me a surface mounted panel out side would nolonger be rain tight if there was a 2" chimminy out the top?

Here's what the code says:

312.5(C) Cables. Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure.

Exception: 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.) or more than 3.0 m (10 ft) in length, provided all the following conditions are met:

(a) Each cable is fastened within 300 mm (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 cable(s) from abrasion and the fittings remain accessible after installation.

(d) The raceway is sealed or plugged at the outer end using approved means so as 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 6 mm (? 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 or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto.

FPN: See Table 1 in Chapter 9, including Note 9, for allowable cable fill in circular raceways. See 310.15(B)(2)(a) for required ampacity reductions for multiple cables installed in a common raceway.

[ December 02, 2003, 12:27 AM: Message edited by: hurk27 ]

 

[hurk27]

Re: Branch circuits entering panel

Oh I forgot the other question:
The amount of cables that are allowed in a romex connector is a listing issue not a NEC issue. It will all depend on what a manufacture has there R/C's been listed for. and there are some that do have a 4 14/2 listing.

 

[a.wayne3@verizon.net]

Re: Branch circuits entering panel

Wayne isn`t it 18 to 24 ins. ????Longer than that is no longer a nipple.I don`t have code book with me for refference.

 

[iwire]

Re: Branch circuits entering panel

Originally posted by bigjohn67:
No. 1
MLO panel mounted in the interior of house, main outside. Does all the MNB's have to be placed in RX connectors and if so what is the max. # of wires per connector? 12/2 rx

Why cant I just use a 2" Male adapter in the top of the panel to bring the wires into the panel?

Not allowed by the NEC and the number of NMs per connector is by the listing from the manufacturer.

Originally posted by bigjohn67:
No. 2
Panel mounted on outside of house. Nipple is permitted with bushing to bring Rx into panel thru the back. If this is allowed by code, why is answer to NO.1 above is that I cant use this same method, why is it allowed outside.

None of what you describe here is allowed by the NEC, you may have local amendments that allow this.

Originally posted by bigjohn67:
We use Rx connectors when the panel is on the interior ( because supervisor says we have to, says because of fire hazard to use 2" pvc adapter), but he allows us to use them on exterior panels.

All applications need NM connectors except for the one exception that Hurk posted.

Surface mounted panel with 1 1/2' to 10' of raceway that the cables enter.

Along with all the rest of the requirements Hurk listed.

There is no place in the NEC that allows the use of a male adapter for entering cables into a panel.

 

[iwire]

Re: Branch circuits entering panel

Originally posted by a.wayne3@verizon.net:
isn`t it 18 to 24 ins. ????Longer than that is no longer a nipple.I don`t have code book with me for reference.

No, the exception allows 18" to 120" of raceway.

Yes longer than 24" is not a nipple and you will have to worry about derating.

Wayne's post is word for word right out of the book.

 

[karl riley]

Re: Branch circuits entering panel

The often overlooked points are that the panel must be surface, not flush mounted. And that the NM sheaths must extend through the PVC into the panel at least 1/4". So you can't strip the sheaths off and just run the conductors through the pipe.

Karl

 

[tom baker]

Re: Branch circuits entering panel

In my opinion 312.5(C) only allows one way to run NM cable thru a sleeve into a panel, other methods would be a violation, or have to comply with 321.5(C).

 

[BAHTAH]

Re: Branch circuits entering panel

In my opinion the installation of NMB cable out the back of a N3R panel into the interior wall of a building has long been overlooked by the NEC. While 312.5(C) talks about the use of nonflexible raceway it only applies where the raceway is installed out the top of a panel as typically found where a panel is surface mounted in a basement for example. While the NEC does not as far as I can see direct any attention to the use of a Male adapter (pvc) and a shorther than 18" conduit to run out the back of a N3R panel into a wall where the NMB is secured, I have done so for many years. I fail to see the logic in the 18" minimum length as long as the cable is properly protected and the conduit is able to be sealed at the building penetration. The area behind a N3R panel is outdoors and subject to water traveling down the wall and is a location NMB would not be listed for use.

 

[bigjohn67]

Re: Branch circuits entering panel

The panel I speak of on the interior is recessed in the wall, flush mount.