Wiring a Junction Box in the Attic

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Old 09-13-12, 02:47 PM
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Question Wiring a Junction Box in the Attic

I've mounted a projector on the ceiling for the theater room, and in the spirit of cleanliness, I'd like to run the power cable into the ceiling(along with the already ran HDMI cable) and plug the projector in somewhere in the attic in a recepticle. Problem is that there are none within reasonable distance up there, so I was thinking of installing my own.

Is it as easy as cutting power to an outlet(the one on the wall by the projector), taking the wiring in the attic TO that outlet and cutting it, then using the twist caps and put them back together, only adding another 12ga wire running into a new junction box?

Basically just cutting in the middle of the I, and splicing a piece right in to make a T? It can't be that simple, is it? (please tell me it is)
 
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Old 09-13-12, 02:51 PM
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For the most part, home electrical work is pretty straight forward but mistakes can cause deadly fires so reading up on the subject first is a good idea. Most recommended reading around here is Wiring Simplified, which is available online and often at the big box stores.
 
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Old 09-13-12, 02:57 PM
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I have a basic grasp on fundamentals and whatnot. Common sense also goes a long way when doing a project. My question was more specifically directed at whether that is the "proper method" to installing a junction box: just cut an existing wire, and splice another into it and run that new one to a new box.
 
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Old 09-13-12, 03:23 PM
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The splices must be made in a permanently accessible junction box. The cable you cut if originally properly installed will be too short for that because there will be little or no slack.You will need two junction boxes. Each positioned so you can get 6-8" of the cut cable in the box. Then you connect the two boxes with a short length of cable.

All grounds are connected together and if the box it metal pigtailed to the box. proper cable clamps (AKA cable connectors) need to be used at each box.
 
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Old 09-13-12, 04:36 PM
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I've mounted a projector on the ceiling for the theater room, and in the spirit of cleanliness, I'd like to run the power cable into the ceiling(along with the already ran HDMI cable) and plug the projector in somewhere in the attic in a recepticle.
How are you planning on getting the power cable through the ceiling? That power cable is not rated for running through drywall. No cable is, including your HDMI cable. You will need to mount a new receptacle flush in the ceiling for the power, plus a connector for the HDMI.
 
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Old 09-13-12, 05:50 PM
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Nash gives the biggest reason against your idea. Flex cords cannot be run behind drywall.
 
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Old 09-13-12, 06:48 PM
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What is the issue with flex cords behind drywall, other that simply being against code?
 
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Old 09-13-12, 07:16 PM
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What is the issue with flex cords behind drywall, other that simply being against code?
Wiring should always be done according to code. This forum will not advise unsafe practices such as willfully ignoring code.

Example: Your house burns down. The insurance company sees non code compliant wiring. Even if that wiring is not really the cause it may be enough for the insurance company to reject your claim using it to establish a pattern of non code compliance.
 
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Old 09-13-12, 07:25 PM
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That I understand, I was just wondering what the reasoning behind that paticular code was. I fully understand complying with code, I just have the 'why?' questions to further my understanding.

Sorry to hijack!
 
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Old 09-13-12, 08:53 PM
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What is the issue with flex cords behind drywall, other that simply being against code?
I'm guessing that you aren't familiar with the NEC. As thick as it is, the NEC doesn't give the reasons for its prescriptions. It simply states them. Since we know the Code is based in life safety, and it may cost us our license to ignore any part of it, we follow it. If we want to make an interpretation that we think someone might question later, we reach consensus on the job site and then, in a meeting with the inspector, we annotate all of the relevant sections of the prints and specs and have the inspector initial and date those annotations.

In this case, though, we can posit a couple of reasons:
  1. The flex cord can, and will, be abraded by the drywall, plaster, concrete, CMU, wood, etc.

  2. The means of disconnect for any cord-and-plug connected load must be visible from the device, and accessible. IOW, you must be able to unplug the projector (or whatever) when you see a problem with it, or just want to work on it, without having to leave the room - let alone climb up into the attic.
Thanks for asking, but don't expect that we'll always be able to cite a reason. Above all, don't expect any reasons we cite, including the two I just gave, to be accurate in terms of the actual reasoning behind the rule. We interpret and apply the Code. We do not, and cannot, read the minds of the members of the committees who develop it. And we certainly don't second-guess them.
 
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Old 09-13-12, 09:08 PM
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I would guess that part of this has to do with deterioration of the flex cord and also smoke spread.
 
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Old 09-13-12, 09:21 PM
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Thank you! That basically answers my questions. Sounds about like the regs in my field...
 
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Old 09-13-12, 11:10 PM
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The best thing will be to install this new receptacle in an 'old work' box in the ceiling right behind the projector. This is a very common (and code compliant) way of doing it, so no home theater aficionado will fault you for it.

Assuming your projector is like most and it has the standard "computer-style" detachable cord (which technically would satisfy the 'means of disconnect' Nash, but of course it doesn't change that flex can't go through a wall), you can get a 1 foot replacement for about $5 that will prevent you from having to coil up excess.

As for the HDMI cable, you won't want that passing through the drywall, for several reasons already mentioned. There are HDMI "pass through" plates, which allow you to safely pass the cord through without having an ugly hole or allowing air leakage or a way in for insects.

 
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Old 09-14-12, 05:11 PM
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Flexible cords are not rated against fire, so they cannot be part of building wiring. You also must use an in-wall rated HDMI cable, as well as all of the other cables you plan on using in the wall, such as speaker and network cabling.
 
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Old 09-14-12, 11:29 PM
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You'd have to really piss off an inspector in order to get him to red-tag speaker or video cables. As long as it is going from one point in a room to another, and isn't going between rooms or penetrating levels, or going through an air handling space, there's no danger. Basically everything carries at least VW-1 flame retardance certification so the jacketing won't burn or support a fire.
 
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