# NM Cable through back of surface mount panel



## paulgarett

I will be installing a new surface mount load center. The back of the panel has two concentric knock outs. The bottom of the box has multiple knockouts, 1/2" and concentric. I have two options for installing the NM cable into this load center. 
Option 1: Install a 1-1/4 2-screw NM connector on back of panel and run all NM cables through this opening
Option 2: Install conduit from bottom of load center to an LB, where the NM cables will be run into the house.

The first option eliminates the need to install conduit and an LB, saving time and money, but it may result in a cleaner panel make-up. 

Option two would be quicker and simpler. Either option means drilling a large hole in the siding of the home to run the cables through. 

Any comments about drilling multiple holes in the back of the panel for the NM cables are wrong. I will not drill multiple holes in the back of this panel when knock outs are provided. This weakens the box and is not neat.

What are the code requirements for using a large 2-screw NM connector 
(1-1/4 inch) to secure multiple (8 or so) NM cables to the back of a surface mount load center? 

Or is using the conduit down from the bottom of the load center and the LB into the building the right way to do it?


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## macmikeman

paulgarett said:


> I will be installing a new surface mount load center. The back of the panel has two concentric knock outs. The bottom of the box has multiple knockouts, 1/2" and concentric. I have two options for installing the NM cable into this load center.
> Option 1: Install a 1-1/4 2-screw NM connector on back of panel and run all NM cables through this opening
> Option 2: Install conduit from bottom of load center to an LB, where the NM cables will be run into the house.
> 
> The first option eliminates the need to install conduit and an LB, saving time and money, but it may result in a cleaner panel make-up.
> 
> Option two would be quicker and simpler. Either option means drilling a large hole in the siding of the home to run the cables through.
> 
> Any comments about drilling multiple holes in the back of the panel for the NM cables are wrong. I will not drill multiple holes in the back of this panel when knock outs are provided. This weakens the box and is not neat.
> 
> What are the code requirements for using a large 2-screw NM connector
> (1-1/4 inch) to secure multiple (8 or so) NM cables to the back of a surface mount load center?
> 
> Or is using the conduit down from the bottom of the load center and the LB into the building the right way to do it?


I'll even drill knockouts into knockouts.... But Arlington makes romex connectors that can handle multiple cables (ul listed too) . Maybe for you those would be the way to go..


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## backstay

paulgarett said:


> I will be installing a new surface mount load center. The back of the panel has two concentric knock outs. The bottom of the box has multiple knockouts, 1/2" and concentric. I have two options for installing the NM cable into this load center.
> Option 1: Install a 1-1/4 2-screw NM connector on back of panel and run all NM cables through this opening
> Option 2: Install conduit from bottom of load center to an LB, where the NM cables will be run into the house.
> 
> The first option eliminates the need to install conduit and an LB, saving time and money, but it may result in a cleaner panel make-up.
> 
> Option two would be quicker and simpler. Either option means drilling a large hole in the siding of the home to run the cables through.
> 
> Any comments about drilling multiple holes in the back of the panel for the NM cables are wrong. I will not drill multiple holes in the back of this panel when knock outs are provided. This weakens the box and is not neat.
> 
> What are the code requirements for using a large 2-screw NM connector
> (1-1/4 inch) to secure multiple (8 or so) NM cables to the back of a surface mount load center?
> 
> Or is using the conduit down from the bottom of the load center and the LB into the building the right way to do it?


Here the inspectors will fail you if you run all the nm in conduit(derating issues) the single nm is not listed to do what you want either.


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## paulgarett

why would inspectors fail for running wires in conduit, the outer sheath would be stripped and the conductors derated properly. 

I never drill holes inside knock outs; its messy and little "hokey." 

My question is, can I run multiple NM cables through a single ko located on the pack of a load center? I would either use a snap-in bushing, an 1-1/4" 2-screw romex connector, or a chase nipple with a screw-on bushing. 

How else would I get all the branch circuits into the surface mount load center?


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## sbrn33

A conduit and lb would be a wet location, wouldn't it.


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## HackWork

paulgarett said:


> why would inspectors fail for running wires in conduit, the outer sheath would be stripped and the conductors derated properly.
> 
> I never drill holes inside knock outs; its messy and little "hokey."
> 
> My question is, can I run multiple NM cables through a single ko located on the pack of a load center? I would either use a snap-in bushing, an 1-1/4" 2-screw romex connector, or a chase nipple with a screw-on bushing.
> 
> How else would I get all the branch circuits into the surface mount load center?


The inspector could fail you because the wire inside of the romex is not labeled and other than assumption you don't know that it's THHN.

Whether you could bring all the cables in thru a large bushing or connector or not is generally up to your AHJ. In most places it's not allowed but it seems like plenty of areas around the country allow it.


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## HackWork

paulgarett said:


> Any comments about drilling multiple holes in the back of the panel for the NM cables are wrong. I will not drill multiple holes in the back of this panel when knock outs are provided. This weakens the box and is not neat.


I don't know how much weaker a panel would get from drilling out some holes, but if the holes are in the back of the panel and the panel is securely screwed to the wall, the holes shouldn't make any difference at all.


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## macmikeman

OK, the part about drilling a knockout thru a knockout was a joke , but tell me what it is that prevents you from punching your own holes in the back side of your panel? 

You could put a box on the reverse side and run thhn thru a nipple and pretty much not have to worry about de-rating since it is less than 18". 

You could run all the romex's into the back of a long gutter keeping two to a hole and then njpple that up into your panel from below. 

You could look into the Arlington brand nm cable clamps I told you about that allow for something like 8 or 10 in one clamp.


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## backstay

paulgarett said:


> why would inspectors fail for running wires in conduit, the outer sheath would be stripped and the conductors derated properly.
> 
> I never drill holes inside knock outs; its messy and little "hokey."
> 
> My question is, can I run multiple NM cables through a single ko located on the pack of a load center? I would either use a snap-in bushing, an 1-1/4" 2-screw romex connector, or a chase nipple with a screw-on bushing.
> 
> How else would I get all the branch circuits into the surface mount load center?


Stripped romex isn't listed for conduit. How will you secure the nm within 12 in of the panel? How many cables is that 1-1/4 in connector listed for? You can do anything you want. Your AHJ can ok anything you do. That doesn't make it code.


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## BBQ

backstay said:


> Stripped romex isn't listed for conduit. How will you secure the nm within 12 in of the panel? .


The NEC allows cable such as NM in raceways. 


From the EMT article 


> 358.22 Number of Conductors. The number of conduc-tors shall not exceed that permitted by the percentage fill specified in Table 1, Chapter 9.
> 
> *Cables shall be permitted to be installed where such use is not prohibited by the respective cable articles. *The number of cables shall not exceed the allowable percentage fill specified in Table 1, Chapter 9.


There I nothing in the NM article preventing it.


Some inspectors might try to fail stripped NM based on 310.11 which is marking requirements. But if you don't strip the NM that will not be an issue. 

The NEC requires the conduit to be sized based on the full cable size anyway, not the conductors inside it.


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## HackWork

BBQ said:


> The NEC allows cable such as NM in raceways.
> 
> 
> From the EMT article
> 
> 
> There I nothing in the NM article preventing it.
> 
> 
> Some inspectors might try to fail stripped NM based on 310.11 which is marking requirements. But if you don't strip the NM that will not be an issue.
> 
> The NEC requires the conduit to be sized based on the full cable size anyway, not the conductors inside it.


He said that he was going to strip it.



paulgarett said:


> why would inspectors fail for running wires in conduit, *the outer sheath would be stripped and the conductors derated properly.*


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## BBQ

HackWork said:


> He said that he was going to strip it.


I know, I was just covering the bases.


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## Dennis Alwon

I am assuming this is an external panel in which case the LB would not be compliant although many areas allow it.

This is one of those issues that has been done around here forever. Not compliant but panels are installed an a short pvc coupling or piece of pipe is use to sleeve the wires into the panel. 

To be compliant it is necessary to install a jb inside and bring all the wires thru a nipple into the box. I have discussed this with inspectors especially where we have a panel and the only way in is thru an LB into the crawl space. Although NM isn't allowed outside in a raceway the inspectors tend to agree that it is a better job to run the nm thru then to cut the NM cable and splice every homerun. You could run UF for your homeruns but you still have the issue of attaching it to the panel. 

If you can find connectors that will allow many cables in then that would be the way to go.


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## backstay

BBQ said:


> The NEC allows cable such as NM in raceways.
> 
> From the EMT article
> 
> There I nothing in the NM article preventing it.
> 
> Some inspectors might try to fail stripped NM based on 310.11 which is marking requirements. But if you don't strip the NM that will not be an issue.
> 
> The NEC requires the conduit to be sized based on the full cable size anyway, not the conductors inside it.


Stripped nm isn't code in a raceway. Splice it in a JB and switch to THHN or some other single conductor.


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## BBQ

backstay said:


> Stripped nm isn't code in a raceway. .


That is not a code fact, that is an opinion. 




> Splice it in a JB and switch to THHN or some other single conductor


Or don't strip it at all and pull NM in the raceway that is without question code compliant.


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## Dennis Alwon

There really isn't a good legal solution. I wish that there were but I really don't think we will see one. I will say that there are thousands of installs in this state where the nm goes thru a pvc coupling in the back of a wp panel. That is the cleanest and best install, IMO but it is not compliant


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## HackWork

I still don't understand why he doesn't just pop some 1/2" holes in the back of the panel, insert some button connectors, and bring the cables in?


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## Dennis Alwon

HackWork said:


> I still don't understand why he doesn't just pop some 1/2" holes in the back of the panel, insert some button connectors, and bring the cables in?


Because then you have to cut out the entire band or make a huge hole in the wall-- a terrible install. I had an inspector who wanted me to do that years ago so I called the state engineers and they said that was a horrible idea and the way I had done it was much better but technically not compliant-- he made the inspector pass my install.


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## backstay

BBQ said:


> That is not a code fact, that is an opinion.
> 
> Or don't strip it at all and pull NM in the raceway that is without question code compliant.


Well, it's the opinion of the state inspectors here. And I don't see a code article to argue it. I just wired a house where the panel was surface mounted on the shared wall in the garage. HO wanted to run the nm in one two inch PVC from the attic to the panel. Inspector said no. This is slightly different from the OP, but I see the problem with too many CCC in the pipe.


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## BBQ

backstay said:


> Well, it's the opinion of the state inspectors here. And I don't see a code article to argue it.


You lost me, I posted a code section that says we can put cables in raceways. 

Can you show me a code section that prohibits it either striped or unstripped?

There is no question unstripped is allowed under the NEC, stripped and missing its marking is less clear.


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## Dennis Alwon

BBQ said:


> Can you show me a code section that prohibits it either striped or unstripped?


What about 334.15(C)-- I realize is is talking about basement walls but I suspect that should follow thru.




> Nonmetallic-sheathed cable installed on the
> wall of an unfinished basement shall be permitted to be
> installed in a listed conduit or tubing or shall be protected
> in accordance with 300.4. Conduit or tubing shall be provided
> with a suitable insulating bushing or adapter at the
> point the cable enters the raceway. *The sheath of the
> nonmetallic-sheathed cable shall extend through the conduit
> or tubing and into the outlet or device box not less than
> 6 mm (1⁄4 in.).* The cable shall be secured within 300 mm
> (12 in.) of the point where the cable enters the conduit or
> tubing. Metal conduit, tubing, and metal outlet boxes shall
> be connected to an equipment grounding conductor complying
> with the provisions of 250.86 and 250.148.


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## BBQ

Dennis Alwon said:


> What about 334.15(C)-- I realize is is talking about basement walls but I suspect that should follow thru.


I would say that applies to what it applies to and no more. 

We often run MC cable in pipe, do you think we strip it or leave the armor on?


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## backstay

Dennis Alwon said:


> What about 334.15(C)-- I realize is is talking about basement walls but I suspect that should follow thru.


Thank you Dennis. Now how many current carrying conductors dose he have to size the conduit.


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## Dennis Alwon

BBQ said:


> I would say that applies to what it applies to and no more.
> 
> We often run MC cable in pipe, do you think we strip it or leave the armor on?



All I am saying is that applies to a sleeve in a pipe down a basement wall so why would that not apply elsewhere. I can see an inspector use that section.

Normally when I run mc into a conduit I have a fitting at the top but yes it would be stripped. I don't think that is the same as a sleeve.


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## Dennis Alwon

backstay said:


> Thank you Dennis. Now how many current carrying conductors dose he have to size the conduit.


It depends on the length of the sleeve. Over 2' then he would need to count current carrying conductor's.


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## BBQ

backstay said:


> Thank you Dennis. Now how many current carrying conductors dose he have to size the conduit.


What does the number of CCCs have to do with the size of a conduit containing cables?

NEC 358.22 tells us how to size the conduit 



> The number of cables shall not exceed the allowable percentage fill specified in Table 1, Chapter 9.


If we to follow that we would find it is based on the cable dimensions.


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## BBQ

Dennis Alwon said:


> All I am saying is that applies to a sleeve in a pipe down a basement wall so why would that not apply elsewhere. I can see an inspector use that section.
> .


I understood what you were saying.

The section you have quoted is recent, the fact it was written in a way that is not supported elsewhere in the NEC does not surprise me.





> Normally when I run mc into a conduit I have a fitting at the top but yes it would be stripped. I don't think that is the same as a sleeve


If it is a sleeve clearly it must be whole and not stripped. I have not once in this thread said anything about a sleeve.


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## Dennis Alwon

Sorry I thought that was what we were talking about from the op's question


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## BBQ

Dennis Alwon said:


> Sorry I thought that was what we were talking about from the op's question


I went back and read the OP I see nothing about a sleeve.

But that is up to each of us as it is not defined in the NEC.

To me a sleeve is just a section a of pipe on its own and not connected to cables or enclosures. 

What the OP has (IMPO) is a raceway, of course to be compliant the cables need to be entered into it correctly not just stuffed into it.


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## Dennis Alwon

I see a sleeve as any section of raceway that is not complete. As you know section 312.5(C) allows cables to enter incomplete raceways in the top of some panels if they meet all the requirements in the exception. I see that conduit as a sleeve.

So obviously we are looking at it from different directions- as you said it is not defined in the NEC


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## BBQ

Dennis Alwon said:


> I see a sleeve as any section of raceway that is not complete. As you know section 312.5(C) allows cables to enter incomplete raceways in the top of some panels if they meet all the requirements in the exception. I see that conduit as a sleeve.
> 
> So obviously we are looking at it from different directions- as you said it is not defined in the NEC


The exception to 312.5(C) calls them raceways, not incomplete raceways and not sleeves. 



> (C) Cables. Where cable is used, each cable shall be se-cured 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 enclo-sure 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:
> 
> (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 enclo-sure through the raceway.
> 
> (e) The cable sheath is continuous through the race-way and extends into the enclosure beyond the fitting not less than 6 mm (1⁄4 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 con-duit or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto.


Now when I search the NEC for sleeve virtually every instance it is taking about a section of pipe on its own.


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## Dennis Alwon

It really don't see why it matters. The section I first stated has a piece of conduit attached to the box. It is still sleeving the wiring down the conduit. If you don't call it a sleeve that is fine but the result is the nm cannot be stripped. 
Obviously you would not strip it in the middle of a run where the conduit is , what you consider, a sleeve.

The op was basically talking about sleeving the nm thru an LB into a panel. Is that really different then sleeving into a box down a wall? Call it whatever but IMO it would not be compliant in either case into the panel.


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## paulgarett

A lot of replies. I can see how this type of installation is frequently encountered and it varies depending on the circumstances. I do not understand why the NEC has not addressed this issue. There are thousands (if not millions) of surface mount load centers throughout the country where the building's branch circuits enter the back of the box. It would be ideal to have a sub-panel mounted directly behind the main load center, but that does not happen in most circumstances, especially if the opposite side of the main load center is the inside of a bedroom. Punching out multiple 1/2" or 3/4" holes in the back of a cabinet (that already has concentric knock-outs) does not make sense. First of all the cabinet already has concentric knock-outs, secondly it makes the install a lot harder and time consuming, and thirdly, as mentioned in a previous reply, it creates more holes in the side of someone's house or one large hole.
It seems to me the cleanest, simplest, and time saving way to install NM cables into a surface mount load-center is to come through the back of the box, using one chase nipple or romex connector to protect the cables from sharp edges. The cables will then be secured to the wood framing with strapping of some kind (hopefully as close as possible to entryway). The only other method that makes sense, is mounting a sub-panel directly behind the load-center (using a nipple to connect the two). 
There needs to be special fittings or codes that addresses this installation issue. 
Note to readers: I am an electrical instructor and know the NEC very well; I appreciate the NEC quotes and they make a lot sense. As electricians, contractors, etc., how do we address this installation issue? How would you do it?


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## BBQ

Dennis Alwon said:


> The op was basically talking about sleeving the nm thru an LB into a panel. Is that really different then sleeving into a box down a wall? Call it whatever but IMO it would not be compliant in either case into the panel.


If you look at my posts at no time did I say the OPs installation was compliant. 

I was disputing backstay's general comments that NM could not be run in pipe.

As far as the basement section you posted, it clearly only applies to what it says it applies to. If having the sheath enter the enclosure was a general requirement they would not have to include it in that specific section.


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## Dennis Alwon

paulgarett said:


> how do we address this installation issue? How would you do it?



All I can say is it is done here and I try and avoid exterior panels for that reason. I would like to see an exception that allows a chase nipple if it is filled with foam however that would then make derating an issue. There is no good solution here other than to install a large interior JB and splice all the nm cables of pass the cables thru the box into the chase nipple. 

The problem arises when there is no good place for a box in the interior and the jb must go in the crawl space. Now you must set your panel low to the ground -in some cases- or lb out of the bottom into a jb in the crawl.

I am thinking about writing a proposal to accept NM in a conduit on the exterior when the conduit is run vertically into a panel with a conduit fitting such as an LB is employed.


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## Sparky J

Here when it's caught inspectors do not want Romex in conduit (usually underground conduit) because the ground is not insulated and thus not rated for it. Also they treat it like a swimming pool which requires an insulated ground.
Like hack said even if the white and black are thhn (which you'd have to prove) the ground is bare and not rated the same as thhn.


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## Dennis Alwon

Sparky J said:


> Here when it's caught inspectors do not want Romex in conduit (usually underground conduit) because the ground is not insulated and thus not rated for it. Also they treat it like a swimming pool which requires an insulated ground.
> Like hack said even if the white and black are thhn (which you'd have to prove) the ground is bare and not rated the same as thhn.


That makes absolutely no sense. First off it is thwn/thhn that is dual rated for outdoor but I don't believe a bare copper wire is against the code in a conduit except for swimming poles. Heck we use bare copper to ground rods all the time.

The reason nm cable cannot be used in a conduit outdoors is because of art.300.9


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## paulgarett

An interior jb does not make sense because there would have to be access to that box.
If there was access, great. But the installation I am referring to will be as follows.
Surface mount load center on exterior of building, opposite the living room. Branch circuits for this small duplex will run through the back of the load center. This is the cleanest and fastest way. Any other way in my eyes cause code problems or time.
Why can't we as electricians simply install a chase nipple in the back of the surface mount box, run the cables through, then attach the NM cables to the wood framing in the wall within 12" or less from the chase nipple, romex connector, or snap-in bushing. This to me makes the most sense, because its straight forward, clean, and easy. Any other way takes more time and is more complicated. The NEC needs to be revised.


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## backstay

BBQ said:


> If you look at my posts at no time did I say the OPs installation was compliant.
> 
> I was disputing backstay's general comments that NM could not be run in pipe.
> 
> As far as the basement section you posted, it clearly only applies to what it says it applies to. If having the sheath enter the enclosure was a general requirement they would not have to include it in that specific section.


I said stripped nm can't be run in a pipe. And the inspectors here, won't allow you to stuff all the nm into one conduit.


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## Jlarson

You are over thinking this. If the ahj will let all the cables come in through one large connector in the back of the can roll with it.


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## paulgarett

ok. The NEC 312.5(C) is a little confusing. I think their should be a revision. 
thank you.


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## TUNIT

paulgarett said:


> I will be installing a new surface mount load center. The back of the panel has two concentric knock outs. The bottom of the box has multiple knockouts, 1/2" and concentric. I have two options for installing the NM cable into this load center.
> Option 1: Install a 1-1/4 2-screw NM connector on back of panel and run all NM cables through this opening
> Option 2: Install conduit from bottom of load center to an LB, where the NM cables will be run into the house.
> 
> The first option eliminates the need to install conduit and an LB, saving time and money, but it may result in a cleaner panel make-up.
> 
> Option two would be quicker and simpler. Either option means drilling a large hole in the siding of the home to run the cables through.
> 
> Any comments about drilling multiple holes in the back of the panel for the NM cables are wrong. I will not drill multiple holes in the back of this panel when knock outs are provided. This weakens the box and is not neat.
> 
> What are the code requirements for using a large 2-screw NM connector
> (1-1/4 inch) to secure multiple (8 or so) NM cables to the back of a surface mount load center?
> 
> Or is using the conduit down from the bottom of the load center and the LB into the building the right way to do it?


Pretty sure you have to have a point of connection,like connector with a locknut,i do commercial but would think it carries over to residential,but i am thinking you are talking about m/c,or b/x,and sure i am wrong you should be fine with romex,not sure how many you can put in what but never seen the inpectors complain as long as it is strapped right and secure.I woould think ten would be fine in a 1 .1/4


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## don_resqcapt19

paulgarett said:


> ok. The NEC 312.5(C) is a little confusing. I think their should be a revision.
> thank you.


Write one up and submit it...you have until early November 2014, to submit change proposals for the 2017 code.


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## Tigerloose

In this case, the contractor cut a hole in the wall behind panel. Then he loaded up on caulk.





This is unusual. The usual is a big hole and the cabinet is sealed to the stucco top and sides with caulk. Another iteration is mounting a surface mount over an intact recessed cabinet. Both are code violations.

Well that didn't work at all. I can't delete it so I'll just say sorry about that. Dennis, if you see this would you please delete it. Thanks


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