Running Wires in Conduit inside a wall

Discussion in 'Electrical Forum discussion & Blog' started by Andi.M, Jan 30, 2013.

  1. Andi.M

    Andi.M New Member

    Messages:
    3
    Location:
    Virginia
    Here is the situation.

    I am in the middle of remodeling a bathroom on the upper floor of a split-foyer. It is right above the unfinished laundry, where the electric box is situated (the lower level is the basement and above the first floor is an unfinished attic). I have taken everything off down to the framing. In the corner of the bathroom there is a roughly 3x4 enclosed passageway that runs straight from the laundry to the attic. In it, the builders ran the main A/C air duct to upper floor, as well as the flue from the Gas Water heater and Furnace. This chase is enclosed by framing all around and has metal sheeting on the top (to attic) and bottom (to basement).

    I had this idea about running 2 conduits from Basement to attic to “future-proof†the place and get ready for future remodel ideas! Conceptually, I would use one to fish electric wires (I was thinking of the usual 14/2 NM-B and 12-2 Romex NM/B which have been ran elsewhere) and the other to run low-voltage wires (RG-6 and Cat 5e. perhaps speaker wire). The purpose of the conduits would have been to simply have a path (it will be about a 9 foot run) between the attic and the basement) to simplify future wiring.

    As I look into this, there seems to be more to it than the electrician at the local home improvement store conveyed. I am hoping readers here have better ideas:
    1. What other approach would you use (if not what I am trying to do) to accomplish the same purpose? (note: the rest of the house if finished and I won't get the same straight shot to laundry on any future project)

    2. If going the conduit route, I was recommended to use 2 x 1inch PVC 10 foot conduits.
    a. Would the scenario be OK for low-voltage wires;
    b. I have come across things like fill % (seems to be 40% for 1†pvc pipe) for NM wire in conduit. Apparently, there is danger of overheating. But this would barely give me 2 runs and defeat the purpose of what I had in mind! Ideas?
    c. If I run a conduit, what could I do at the two ends for:
    i. Fire protection;
    ii. Prevent Insects from crawling it;
    iii. Preventing heat loss from basement to attic
    Thank you
  2. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,274
    Location:
    Land of Cheese
    Romex is a specific brand name for NM cable. NM is not rated for and should not be used inside of conduit. When installing wiring in conduit one would use individual conductors rated THNN/THWN. There is a maximum number of conductors that could go into each size of conduit, but once there are over 3 conductors they must be de-rated.

    Any holes drilled between floors for pipe/wire/conduit/etc. must be sealed with fire-rated caulking.

    What you are trying to do is not a bad idea, but given that NM cable can easily be pulled through a finished interior wall at any point in the future, it might not be worth bothering.
  3. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,562
    Location:
    North Carolina
    Install a small panel upstairs for future use and install the feeders now. Install at least three 1 inch conduits with boxes on each end for the low voltage stuff.
  4. Jim Port

    Jim Port Electrical Contractor

    Messages:
    156
    Location:
    Maryland
    NM is allowed inside of conduit by the NEC and is sometimes required to be protected by a conduit.
  5. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,274
    Location:
    Land of Cheese
    Jim, there is not a question in regards to the appropriateness of sleeving a single NM cable for protection where it becomes necessary. I do not believe that it is appropriate for distances going between floors in a building.

    I am not an electrician, but I am quite sure you will not find a table in the NEC regarding conductor fill or derating NM cable in conduit. If I am mistaken, please show me what I have overlooked.
    Last edited: Jan 31, 2013
  6. Andi.M

    Andi.M New Member

    Messages:
    3
    Location:
    Virginia
    C

    I wanted to thank everyone who has replied.

    Interesting thought! So, guess how many electric circuits I will likely need for the remodel and pull lines from the electric box to a small panel in the attic, so I will be ready when the time comes...

    Would I connect the circuits to the main electric panel and leave their circuit breakers off at this point?

    In the attic, would I simply use standard wire connectors to terminate / cover each circuit?

    What type of "electric box" would go in the attic? Something like the following?
    http://www.homedepot.com/h_d1/N-5yc...letric box conduit&storeId=10051#.UQuNivLVBdg

    Should I drill holes in the floor and ceiling joists to pull these wires or am I allowed to simply use the chase I mentioned earlier. That way, I would simply make a hole in the metal sheets (less that 1/16" thick) on the top and bottom of the chase to run the wires. Seems a lot easier and would not damage the wood. I just wonder why the builder would not have done so. Is there any concern?

    Use 3 x 1-inch PVC conduits with conduit boxes /w Gasket, like the following? http://www.homedepot.com/h_d1/N-5yc...oreId=10051&superSkuId=202890943#.UQuN2_LVBdg

    How would I "seal" (or would I) the hole on the boxes that remains open? (again to prevent bugs, fire concerns, air flow)

    Am I allowed to simply use the chase I mentioned earlier? That way, I would simply make a hole in the metal sheets on the top and bottom of the chase and run the conduits. Seems a lot easier and would not damage the wood.=Is there any concern?

    Thank you
  7. Andi.M

    Andi.M New Member

    Messages:
    3
    Location:
    Virginia
    Does this apply to low voltage "smart wires" in a conduit, as well? Any source for how to calculating "de-rating" ?!
    Thank you
  8. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,562
    Location:
    North Carolina
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
    New England
    You could install the panel in the attic, but you might be able to make room in a closet that would make checking and resetting them easier. Now, if all's well, that isn't a normal situation. There are code requirements on access both to the sides and above and in front of the panel, so that could limit where you might put one. But, there'd probably be room in a walk-in closet, should one of those be in the plan. With a remote panel, you only need to run a four-wire cable from the main (ground, neutral, and two hots). The size of that depends on the size of the CB at the main you feed it with.
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
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    Location:
    North Carolina
    That sounds like good advice all but the closet part. Panels are not allowed in closets
  11. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
    Cave Creek, Arizona
    quote; Panels are not allowed in closets
    Maybe not, but I find a lot of them IN closets, as long as they have the proper clearance in front of them.
  12. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,562
    Location:
    North Carolina
    Let me correct myself. It is perfectly fine to put a panel in a closet, bathroom, or even a shower. What you can’t do is put overcurrent such as fuses or breakers in that panel in either of these places no matter the clearances.

    240.24(D) Not in Vicinity of Easily Ignitible Material. Overcurrent devices shall not be located in the vicinity of easily ignitible material, such as in clothes closets.
    (E) Not Located in Bathrooms. In dwelling units, dormitories, and guest rooms or guest suites, overcurrent devices, other than supplementary overcurrent protection, shall not be located in bathrooms.
  13. ActionDave

    ActionDave Electrician

    Messages:
    363
    Location:
    Colorado
    This certainly would rule out most garages.
  14. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
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    Location:
    North Carolina
    maybe or maybe not
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