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Attic - Replacing electric - Positioning, how many boxes, checking understanding

Attic - Replacing electric - Positioning, how many boxes, checking understanding

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  #1  
Old 12-02-11, 12:32 AM
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Attic - Replacing electric - Positioning, how many boxes, checking understanding

In "Attic wiring - ceiling light uses 14/2 cable without ground", I discussed that my attic electrical supplies only the ceiling lights, and was done with 14/2 cable without ground. After many helpful responses, I decided I could live with ungrounded ceiling lights and light switches. (Note that the rest of the house was redone before we purchased it, and looks good, with new romex, grounded, and GFCI's near water. That re-wiring job ignored the attic.)

Sigh. Today, almost done with my project, I found several feet of scorch marks on the underside of a fiberglass batt covering one of these wires. The old wiring is fiber/paper wrapped romex, and that stuff's only rated for 50C. While rewiring the ceiling light yesterday, found that some idiot decided to install 90C ceiling light units throughout the house. Previously bagged and threw out all the other batts under bad lighting conditions, could have easily missed many more scorch marks.

After finding what only didn't become an attic fire due to a small temperature difference, or lack of oxygen underneath the batts, I've decided I'm running all new wire in the attic.


So, I'm looking for some pointers on effectively running two new circuits into the attic. (Some of this is reassurance that I'm thinking along the right lines.)

Question 1 - Nothing is in the way, because there's no insulation at all now. Should I run the electrical and have junction boxes along the attic "floor", or should I run the electrical and have junction boxes along the attic "ceiling"? I've seen some people say to run everything along the floor, so the electrical is insulated against the summer heat. (I live in Michigan - not too hot, but we do sometimes hit 100F.) I've seen others say to run everthing along the ceiling, so everything is more visible and accessible, and only going into the insulation when coming up from the basement or down to a light or light switch. I think the floor will be faster, and would need half as many junction boxes if question #2 goes my way.

Question 2 - Assuming that I'm running everything along the attic floor, should I use a deep junction box at each light that the light hangs from, containing all the wires associated with that spot? Or, should I not only have a junction box that the light hangs from, but a nearby junction box to handle all the splicing, and only having the cable that is going to actually connect to the light in the junction box that the light hangs from? The first way uses less junction boxes, but the second way could be less confusing for a future person to look at from underneath the attic. Basically, which of these images am I doing?


-------------------------------------- (or) ---------------------------------------



Question 3 - Are these two images that I made correct? For example, if using just one junction box at each light, am I having 4 wire nuts in each junction box? A hot wire nut, combining the incoming black, the switch black, and the outgoing black (if there's a box behind this one.) A neutral wire nut, combining the incoming white, the light's white, and the outgoing white (if there's a box behind this one.) A ground wire nut, combining the junction box's grounding wire, incoming bare copper, the light's bare copper, the switch bare copper, and the outgoing bare copper (if there's a box behind this one.) And, a second hot wire nut, combining the switch white remarked black and the light's black?

Question 4 - Do they make a junction box that is permanently open on one side (the side the light's on) and accessible on the other by removing a screwed on plate? It would be physically much easier for me to be able to access a light's junction box from the attic as well as from underneath.

Question 5 - I'm pretty sure about this, but want to make sure. I'm doing two lighting circuits. (So, if one breaker trips, there's still some light.) It's OK to run only one cable for each circuit up to the first junction box in the attic for that circuit, and chain them from there going forward, right? Just want to make sure because right now, each light has it's own cable coming up from down below. But those run past the light switch first, so I'm guessing it was easier to do it that way as new work. Fishing all those spots would be a nightmare, so I'm getting to the attic in one spot, and just coming down for the light switches.


Thank you all SO MUCH!
 
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  #2  
Old 12-02-11, 09:30 AM
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If you want an fixture outlet-box installation such that the connections between the Branch-Circuit conductors and the fixture leads are
accessible both from below the box and above the box you can use
a 4" square "extension " box , provided the box installation complies
with NEC Art 314.27, Outlet Boxes, (A), (2) Boxes at Fixure Outlets.

This requires the box be fastened to a framing member , the ceiling
joist. Also , the bottom of the box must be fitted with a "rough" cover
that has enough depth to be flush (even) with the celing finish , and
the top of the box must be sealed with an approved OB "blank" cover
 
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Old 12-02-11, 10:36 AM
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PATTBAA - Thank you for your reply. I know what you mean by the OB blank cover, but I'm not sure what the term rough cover means. The old boxes aren't flush with the ceiling finish, but I'll make sure the new ones are!
 
  #4  
Old 12-02-11, 11:49 AM
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Current code requires a neutral at the switch. You would need to run a 3-conductor, with ground (total of 4 wires) between the switch and the ceiling junction box.
 
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Old 12-02-11, 04:16 PM
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Luana - Thanks for pointing that out! Wasn't aware of that. If I'm understanding you correctly, there needs to be a neutral accessible, by using one wire, since the neutral will never be interrupted?

I've decided that even though I have single switches and just lights, that I'd like to run the correct cable that would allow a future installation of a light/fan combo unit, having it be possible for that to be controlled either by a single or dual switches. If I want to do all this and have a neutral accessible at the switch, is it 12/2/2 with ground cable that I should be running?

Making sure to follow code and have the functionality that I want, is this the correct way to go?

 
  #6  
Old 12-02-11, 04:58 PM
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Luana - Hmm. Looks like the neutral at a switch requirement is in NEC 2011, and Michigan (my state) is still on NEC 2008. Am I correct that the neutral is only being added to the requirements for smart switches? Wonder if it's worth running 12/2/2 over 12/3. Unsure how smart switches will be in the future, they haven't peaked my interest yet. My local prices are:

$67 - 250' of 12/2 w/ ground
$120 - 250' of 12/3 w/ ground
$233 - 250' of 12/2/2 w/ ground

.. So it's a $133 difference to bring the neutral to the switches.
 
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Old 12-02-11, 05:25 PM
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Sorry to everyone for making so many replies today going in different directions. I've learned a lot today, thought through a lot, and changed my mind a lot.

I'd love to run smart switch ready cables, or at least cables that can also run a fan. But, cost is a real problem now.

I may regret it later, but we are going to treat this as a "make the house safer" project rather than an add functionality for something we may or may not ever use (fans, smart switches.)

I'm just going to run 12/2 w ground everywhere, instead of 12/3 or 12/2/2. The few hundred dollars difference is a tremendous amount to us right now.
 
  #8  
Old 12-03-11, 02:00 AM
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Thanks for everyone's responses! One more question about this post, sorry guys, LOL!

I'll be putting the junction boxes high enough that insulation won't cover them.

Where I could run a particular cable along the attic "floor" or "ceiling", which should be my preference? Some say to run the cable along the floor, so the electrical is insulated against the summer heat. (I live in Michigan - not too hot, but we do sometimes hit 100F.) Others say to run the cable along the ceiling, so if the cable heats up, it can dissipate easier than if it was buried in insulation. I will be using a combination arc fault GFCI breaker, if that makes much of a difference.
 
  #9  
Old 12-03-11, 01:44 PM
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I would run the cables where it is easiest, taking into account the possibility of physical damage after installation.

On the neutral to the switch box issue...why not run two cables? One for power (hot and neutral) and the other to the lamp. This would likely be less expensive than buying a roll of four-conductor. Just be sure to mark the cables in the junction boxes.
 
  #10  
Old 12-04-11, 01:18 AM
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Awesome. Thanks! I'm leaning toward having them high up. Just seems cleaner to me to not have them buried, without there being a clear reason to go one way or the other.

Want to double check the minimum distance that I can have between the underside of the roof deck and the electrical cable. Believe it's 1.5" (without getting into metal plates.) In some areas, I might attach to the bottom of a 2x4 running along the roof deck. I can't remember if they cheated both dimensions of the 2x4, but whether it's actually 1.5x3.5 or 1.5x4, that would give me a minimum clearance of 3.5". Just want to make sure there's no other special consideration needing to be given with a roof deck.

I thought I read that everything needed to be in one cable. I got that impression from seeing a post where someone cited a NEC rule saying this. But, perhaps I mis-understood where that rule applies. Perhaps that rule was regarding having only one cable between the same endpoints, which I wouldn't run into if I had one cable going to splicing junction box and the other cable to the lamp box. Having the neutral at the switch would mean I wouldn't have to have the switch go back into the splice junction box to pick up the neutral there.
 
  #11  
Old 12-04-11, 02:16 PM
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In case anyone runs by this post in the future, I wanted to reply that I'm seeing numerous sources all say that FHA guidelines are that everything should be at least 3" away from the roof deck. Didn't find something saying that on fha.gov or hud.gov, but I'm comfortable believing that's the rule since that's what everyone's saying.
 
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