Vertical run of 20-30 NMs??

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Old 03-07-09, 12:16 PM
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Vertical run of 20-30 NMs??

Getting ready to do a total overhaul of a second floor unit in a 2 family. The only good spot for the panel is on the first floor entryway, which means I'll need to have anywhere from 20-30 NM-Bs (mostly 12-2s) running from the middle of the 1st floor, all the way through the 2nd floor, and into the attic, where they will attach to a 2x6 border I'll be nailing around the attic for distribution.

I can't seem to find anything code-specific as to the proper way to do this fairly long vertical run (12 feet or so).

The easiest seems to be to put some 2x3 or 1x3 cross braces in the vertical stud cavity every 4 feet or so and just staple everything to it. The concern I have with that is that on the second floor, this will run through an exterior bedroom wall, and having these braces seems to be asking for someone to drive a picture nail right into it, where if the cables were just hanging freely, they would theoretically bend and flex out of the way as the nail touched them (or at least have a better chance of it). Yes I would keep them set back so the cables are dead center in the 3.5" space and along with the 1/2 inch rock, the average hanging nail shouldn't be a problem, but still, people don't always think about the length of the nail they're using to hang something, and if they're hanging a mirror, that 2" nail would be cutting it awful close, especially if they grab a 3" nail out of their junk drawer :-) Yes, I'm a bit paranoid about safety.

Actually my ideal scenario is to run several schedule 40s, but to maintain proper 40% fill and CCC derating, I could run 4x12-2 through 1.5" conduit (or 3 through 1.25). Since my studs are 16 OC, that would mean 8 conduits (enough for what I need plus some future growth) would require opening the entire bottom and top plates, and I'd only have access to the interior side to put on a metal plate, which I don't think would fly, but maybe. Though I guess I could notch the plates, leaving about 1" of wood on the outside, and use a metal plate on the inside, but then the conduits are touching the back of the sheetrock with no gap.

Wasn't sure what the generally accepted method is. Regardless I'll have at least one schedule 40 in there for future use, but trying to determine the best method of doing the rest.

Funny thing is, if you were doing this in an old work scenario, it seems generally acceptable to just drop em all down through with nothing securing them.
 
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Old 03-07-09, 01:02 PM
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Putting the braces across sounds like the best plan and use some pvc conduit just for future use.

Where you staple to the brace, you could always "fabricate" a nail plate to secure from stud to stud to protect the wire.
 
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Old 03-07-09, 02:04 PM
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Myself and Wirenut will agree with this matter this is the best way to deal by putting in 1X4 board and use that for bracing the NM cables.

Just rember the golden rules about keeping in centre in the stud cavity so you don't get any stray nail comming in and hit one of the cables that will be no fun to replace it if nail hit it.


Yeah it good idea to run a conduit so in future you will need to use to add a circuit or two in latter time if the situation arise and make sure you get 6X6X4 juction box on that end of the conduct run.

Make sure you double check with your local code related to the AFCI requirements they are getting picky on that so double check with electrical inspectors { some will tell ya some won't if latter then ask for what the genral requirement in the area }

Merci, Marc
 
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Old 03-07-09, 02:05 PM
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Originally Posted by wirenut1110 View Post
Putting the braces across sounds like the best plan and use some pvc conduit just for future use.

Where you staple to the brace, you could always "fabricate" a nail plate to secure from stud to stud to protect the wire.
Yeah that thought had crossed my mind, along with putting the braces 2' up from the bottom and 2' down from the top, maintaining a reasonable 4' distance but keeping them mostly out of the way of where a nail would go in. I'd leave a tad bit of slack inbetween too so they can move around.

The conduit buys me some benefit as the wall in question is one I want to close up and finish before the whole project is done (I'm living in it and doing sections at a time so need to finish this first part and move into it), if I do the cross braces I need to pre-run all the wire, but that's not a huge deal. I think trying to do it all with sch-40 is going to be too tight of a fit.

Another thought I had was putting in a thin metal raceway, almost like a piece of duct, but it seems to be a matter of opinion as to whether the # of CCC's is a factor when you do that, and I'm expecting enough resistance just getting the permit in my town as they're one that doesn't like to give out homeowner elec permits. I figure the more standard I keep everything the less resistance I'll get.

With the cross braces, the top and bottom plates are easy, I'll just open up 2 1" x 4" slots (or even 4 1x2") in them and feed everything through them. The wires will fan out above and below the slot so well under the 24" "bundling" limit.

Thx for the input.
 
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Old 03-07-09, 02:12 PM
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Originally Posted by french277V View Post
Myself and Wirenut will agree with this matter this is the best way to deal by putting in 1X4 board and use that for bracing the NM cables.

Just rember the golden rules about keeping in centre in the stud cavity so you don't get any stray nail comming in and hit one of the cables that will be no fun to replace it if nail hit it.


Yeah it good idea to run a conduit so in future you will need to use to add a circuit or two in latter time if the situation arise and make sure you get 6X6X4 juction box on that end of the conduct run.

Make sure you double check with your local code related to the AFCI requirements they are getting picky on that so double check with electrical inspectors { some will tell ya some won't if latter then ask for what the genral requirement in the area }

Merci, Marc
Yup the brace will be a bit behind center so the cables themselves are perfectly center.

I'm going to play it safe and do AFCI for bedroom lights and receptacles. Only adds $100 bux or so for the 3 bedrooms (shared lighting ckt) and don't have to worry about how picky they are. Unless something real new has come out, that's the only AFCI spot I know of. I'm hoping to do low voltage fire alarms too so I don't have to get a waiver to have the bedroom ones non-AFCI (though it seems pretty standard practice). Still trying to decide between GFCI receptacles or breakers for kitchen and bath, probably just do the receptacles even though they tend to die quicker.

Now its just a matter of convincing them to give me the permit. MA state law actually says a homeowner doesn't even need a permit, but I don't want to go that route as I'm sure it would tick off a few people. It will be a fun project once I stop worrying about all the politics involved.
 
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Old 03-07-09, 02:43 PM
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Getting ready to do a total overhaul of a second floor unit in a 2 family.
This may be the one fact that the others are missing. I assume that you mean that this second floor will be rented to a family other than your own, if so then you may be completely prohibited from doing any wiring, even though you own the home. Generally speaking, rental units are not allowed to be wired by the homeowner and even multiple units in the same building are generally prohibited from being wired by anyone other than a licensed electrician.
 
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Old 03-07-09, 02:50 PM
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Good point Figures it was the first sentence and I missed it...Beer 4U2
 
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Old 03-07-09, 08:29 PM
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Originally Posted by furd View Post
This may be the one fact that the others are missing. I assume that you mean that this second floor will be rented to a family other than your own, if so then you may be completely prohibited from doing any wiring, even though you own the home. Generally speaking, rental units are not allowed to be wired by the homeowner and even multiple units in the same building are generally prohibited from being wired by anyone other than a licensed electrician.
Its grey area, I'm living in the unit, and my state typically considers owner occupied 2 family the same as a single family for just about everything. Sure I may rent it out at some point but that's no different than working on a 1 family then selling it. Homeowner building permits are allowed for 1 or 2 family as long as you live in it, so homeowner electrical permits shouldn't be any different, shouldn't being the key word, it seems to be based on the opinion of each towns officials.

Basically the law here says if you're not charging for the work or doing it as a professional, you don't even need a permit to rewire a shopping mall. A bit crazy, but that's the way it reads. If they refuse to give me a permit, I will bring it to the state and get signoff from them.

I have the option of hiring an electrician to act as supervisor and do the grunt work myself, assuming I can find one who will do that (they do exist). If I meet a lot of resistance and find one willing to do it for a reasonable fee, I may go that route.

But that's all beside the point, I obviously have to deal with the permit hassle myself and am aware that I may face some challenges.
 
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Old 03-08-09, 08:29 AM
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For the convenience factor and cost difference I would install the GFI receptacles. No need to run to the panel if it were to trip and about $20 cheaper too.
 
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