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Question about wiring for HPWC

Discussion in 'Model S: Battery & Charging' started by locdog284, Mar 19, 2013.

  1. locdog284

    locdog284 Member

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    I am planning to have a HPWC installed when it comes in (est. to take 1-2 months) and wanted to do a couple things myself before it arrives to ensure quicker and cheaper installation. Specifically, I wanted to run the wiring myself from the Circuit breaker to the location where the HPWC will eventually be installed. The box with the breaker is located inside of the garage and I want to install the HPWC about 5-10 feet away from this box in the same garage. The wiring will need to exit from the top of the circuit box (which is between two studs) and run upwards into the attic above. From there, the wiring will need to run along the subfloor to the attic area located directly above the location marked for the HPWC. The wiring will then come down between the studs and behind the garage wall until it reaches the specific spot where the HPWC will be installed. The question that I had was regarding the requirements for running this wire inside the walls and inside the attic. I know that I will need to use two 3-gauge THHN wires for the two live wires and am planning to use 8-gauge THHN (Green) for the grounding wire. I was planning to run these inside of 1" conduit inside of the walls, as I do not want the conduit to run on the surface of the walls, and eventually I want the conduit to run into the back opening of the HPWC so that it will remain entirely concealed.

    My question was, what would be the best (or easiest) type of conduit to use for this installation since it will require a couple 90 degree or so bends? Can i use flexible nonmetallic conduit, i.e. ENT, like the blue smurf cable that is sold at Home Depot by Carlon? [Link: Carlon 1 in. x 25 ft. Electrical Non-Metallic Flex Tubing-12008-025 at The Home Depot ] The reason I wanted to use this conduit was because it was easily available at Home Depot and is flexible so I could run it without worrying about using fittings at the bend and corner areas. If this tubing will not work for this specific purpose, then what tubing or conduit should i choose to use (preferably conduit that is available at local hardware store like Home Depot)? I was able to find rigid 1" conduit in both EMT and PVC on the Home Depot website and both are available at my local Home Depot in Texas, but thought that flexible conduit would be easier to run in this case. I could not find any other 1" flexible conduit (either metallic or nonmetallic), other than the Carlon Blue flex tube, on the Home Depot site that showed it was available at a store location near to me, as the ones I found on their site either were online only or were not available at any home depot in the Dallas, TX metroplex (unless the site is incorrect regarding the in-store availability of certain products). Perhaps I am also searching incorrectly and thus not able to find the correct product that is readily available at all stores. Nevertheless, any recommendations or advice on this front would be much appreciated.

    My second question was: what would be the easiest way to fasten the conduit along the wood studs as it runs up into the attic from the circuit breaker panel and runs down from the attic, behind the garage walls, toward the location marked for the HPWC (Is there any way to possibly secure the conduit along the wood stud behind the walls without removing the drywall in these areas)?

    Lastly, besides having to securely fasten the conduit at locations of every 3 feet, are there any other requirements for me to keep in mind as I perform this installation?

    Thank you in advance for any assistance with these issues. I appreciate all of the help that anyone can provide.
     
  2. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Yes, "smurf tube" can be used -- the blue, not the orange stuff -- with a couple of limitations -- it cannot be exposed, so it must always be concealed within ceilings, walls, and floors; it cannot be subject to > 122 degrees F ambient temperature (attics) unless listed for greater temperature; and anywhere you *can*, it must be attached every 3 feet for support (it doesn't have to be supported in walls where you fish it). You must use proper connectors to attach it to the panel and back of the HPWC (i.e., the wires can't simply come out of the tube and go into the HPWC, the conduit must be attached to the panel and HPWC securely).

    NEC 362 covers this.

    If you take open the walls, you must fasten the conduit with standard conduit clamps; but you don't have to, for old work you can fish down a wall without securing it as long as you've secured the conduit up on top.

    See above. :)

    NP.
     
  3. wycolo

    wycolo Active Member

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    Why not just use steel EMT across the wall, exposed, to an exposed HPWC? One 10ft length of EMT plus sundries does the job. It is a garage!
    This seems like a military contractor approach.
    --
     
  4. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    A garage to some is a shrine, I know of people who have opened up walls to run new air lines and such, then re-drywalled it and painted it. I can understand.
     
  5. wycolo

    wycolo Active Member

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    Garage as Shrine:

    Ok, then just notch the emt into the studs, flush, so it can be sheetrocked/plastered over as if nothing happened. This would be easier as you would come out of the service panel (which I assume is flush mounted, not surface mounted) in straight line emt run. Then a 1900 box in the wall to support the HPWC unit. ALL steel. Bulletproof.
    --
     
  6. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Easier to fish than to notch studs in old work, IMO. Notching studs requires you to open the walls and cut out the material, then patch it all back up. If you're fishing and have access from the top or bottom, it's much easier. EMT in notches seems military grade to me :)
     
  7. locdog284

    locdog284 Member

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    Thanks for the responses! As FlasherZ said, I would prefer not to have EMT running across the surface of the wall.

    With your response in mind, the Texas summers do get pretty hot and I can imagine a scenario where the temperatures get pretty close to 122 degrees F inside of the attic. I was actually thinking about it more, and realized that rigid conduit may not be difficult after all since all I have to do is go straight up one wall, straight across the attic floor and straight down another wall. If this is indeed the path I would need to take, would you then recommend using PVC Conduit or EMT? Does the rule where you don't have to secure the conduit along the studs behind walls apply to all types of conduit or only ENT (as long as the conduit is secured on top)?

    For the 90 degree turns, I can use fittings instead of bending the pipe, correct?

    Lastly, what kind of fittings would I use to secure the conduit to the HPWC and panel (and would the same fitting work for the HPWC and panel)? Also, is a box required in the wall to support the HPWC unit?



    Thank you so much again, you have no idea how much you have already helped me with this issue.
     
  8. carrerascott

    carrerascott FUEL FTR

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    We cut the drywall out to run the wiring for the 14-50, and will run through the same path for the HPWC (not the same holes through the studs of course). Prefer a clean install, so will drywall over it once it's done. You can see the cutouts in the drywall in this pic. The HPWC will be just to the left of the AC unit once installed. The electrical panel is on the right side of this pic.

    hpwc.jpg
     
  9. Park2670

    Park2670 Member

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    If I was installing a charger hookup, I would want the same thing. I dont like having wiring on the outside of the drywall.
     
  10. wycolo

    wycolo Active Member

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    With circular saw cut into wall & studs the depth you want to house emt. Use carbide blade so if you hit nail it won't matter. You end up with channel like carrerascott did. Emt in case someone in future nails into wall. Btw, wow, clean garage!

    Surface emt can be mated to wooden chair rail to increase esthetics. I'm guessing OP has a huge cabinet right in this particular space, as luck usually has it. :smile:
    --
     
  11. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Two things with this approach:

    First, if it's a load-bearing / engineered wall, be aware that there are building/construction code implications to notching studs. You're not permitted to notch more than 25% of the depth of load-bearing walls, or 40% of non-load bearing walls. You won't be able to notch for 1" EMT in 2x4 load-bearing walls.

    http://files.engineering.com/download.aspx?folder=2fda658c-dda7-403f-9165-d97f6092084c&file=notch_and_holes.pdf

    Second, use nailing plates to cover the finished work if you're going to notch the studs. EMT won't provide as much protection as nailing plates against piercing from screws and nails and can save a life. In addition, note that some inspectors will interpret notching as a disqualifying feature of NEC 358.30(A) exceptions #1 and #2, which allow for unfastened conduit in finished walls. EMT must be fastened every 10 ft. and within 3 ft of each termination point. Nailing plates will accomplish this.
     
  12. wycolo

    wycolo Active Member

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    > You won't be able to notch for 1" EMT in 2x4 load-bearing walls. [FlasherZ]

    2x4 load bearing walls?? Really?

    And the remote possibility of someone actually driving a sheetrock screw *into* round emt hidden under plaster such that any voltage would not be shunted to ground thus tripping breaker immediately? Couldn't do it if you tried all day. Maybe a gunpowder nail-gun. LOL!!
    --
     
  13. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Yes. Found in older homes.

    I've seen it happen with drywall screws and nails. It generally happens when the screw or nail is helped by something else, pressed against a framing member or so.

    Breakers won't trip before you receive a shock or are subject to an arc flash.

    Nailing plates are cheap and will save your life.
     

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