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HPWC install: 90 degree bend in 6/3 THHN?

Discussion in 'Model S: Battery & Charging' started by ElectricTundra, Mar 6, 2015.

  1. ElectricTundra

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    #1 ElectricTundra, Mar 6, 2015
    Last edited: Mar 6, 2015
    I have a couple of concerns with the way electrical guys are installing my HPWC.

    - The 6/3 feeder (THHN?) is bent at a very sharp angle in the wall. When I was younger I was taught that a bend should generally be fairly wide and never less than 4 times the width of the cable and that really tight bends can result in a hotspot and potential fire. This is about 1 or 2 times the width of the cable. It's in a 2x4 wall so about 3.5" of space which is tight.

    - None of the strain reliefs had enough thread depth to make it through the mounting panel and the charger itself so they just used a bushing. OK?

    I don't want to make an issue out of something that isn't an issue.

    HPWCWire.jpg
    Thanks,
     
  2. wycolo

    wycolo Active Member

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    Photo or it didn't happen. :smile:
    --
     
  3. ElectricTundra

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    D***. Tough group. Had to drill a hole in a perfectly good wall, find some wire, bend it and stomp on it, drive to the hardware store to get a bushing since all I have on hand are clamps, get the entire rig to sit in the wall, get a pic, and post it. Sheesh :)

    I was trying to add the pic while you were posting and somehow ended up creating a new thread and can't find the delete for the dupe thread anywhere. :cursing:
     
  4. FlasherZ

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

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    NEC specs are no less than 5 times the diameter of the cable.

    That appears to be NM-B cable, which means the entire cable assembly diameter must be considered instead of individual wires. That sharp 90" that I think I see is a no-no with NM-B cable. You can legally make a 90 degree turn work in a wall but you pretty much have to bring in the cable at the far back side of the stud and roll it in slowly. Of course, it's unclear how he's going to bring it in - if he uses an NM-to-rigid connector with some PVC to feed the HPWC, then he can consider the diameter of the wires instead of the cable unit.

    It's going to depend upon how he plans to terminate it.
     
  5. llavalle

    llavalle Member

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    #5 llavalle, Mar 6, 2015
    Last edited: Mar 6, 2015
    It's the reason why I decided against running the wire behind the HWPC. I came in from the left side.. and even doing that was a bit a of a mess inside : the electrician had to loop the wires to make a large enough radius for the wires. Picture incoming...

    edit : picture

    I have 2/0 AWG Aluminium feeding my disconnect and 3 AWG Copper wire to the HPWC.
    IMG_20150221_105700.jpg
     
  6. ElectricTundra

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    Thanks for the info. He's coming in the back of the HPWC via that non strain relief bushing. Should he be able to make this work in a 2x4 wall or does he need to come in the side?
     
  7. FlasherZ

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

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    In my opinion, it's not the best job in the world but I think he'll be able to make it work. First, whlie it works as a bushing, that's a PVC conduit connector for boxes; it's not really intended for that, but it'll work. The 6/3 I use is .65 in, so bend diameter is going to be 3.25" radius, which can fit within a 2x4 width just barely, if the cable is pushed up against the back side of the 2x4 wall. I think an inspector would frown at it, but may conclude it's legal. The cable doesn't appear to be attached to framing members - but that's legal in old-work as long as it's attached at the top of the wall. There's no support for that cable in that PVC connector (no clamp), so the entire cable's weight is only supported at the top of the wall.

    It's the fastest / easiest way to do it without opening the wall a bit more (and subsequently patching it).
     
  8. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Nice install.

    I like the 270˚ turn inside the HPWC for a larger radius on the #3 wire, and great using the disconnect switch to transition from the 2/0 AL to the #3 CU.

    I assume that the AL ground wire did get connected later.
     
  9. llavalle

    llavalle Member

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    Yep, I took that picture during the installation, the ground wire did get connected ;) The 2/0 AL wire was his idea (the electrician). I had about 65' to do, it was cheaper that way... and in any cases, here in Quebec, Canada, you're required to get a lockable disconnect switch in the same room. Most of the time, they pass inspection by putting a subpanel in the garage (which I did) but since a breaker is not lockable, it's not 100% safe.

    Btw, I realize that 2/0 is overkill for 100amp (1AWG is fine) but we bought that for feeding my subpanel at 125A. It was easier to just buy 10' more to go from the subpanel to the disconnect switch.

    There is close to 20KW passing in there, better be safe!

    Now if that disconnect was smaller... At the Service Center, they have these cool rotating switch but they're rated "4X" (you can spray them with a hose) and are worth $500+ a piece (hubbell hblds10ac)

    http://sigma.octopart.com/29790707/image/Hubbell-Wiring-Device-Kellems-HBLDS10AC.jpg
     
  10. ElectricTundra

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    It is old work so you're right that nothing is supporting the cable in the wall. With that kink that he currently has in it, should I get him to pull a new one (I don't think he's got enough slack in the current cable to cut it off) or leave it as is? Dangerous as is?
     
  11. wycolo

    wycolo Active Member

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    Having seen llavalle's, now I want one! - Lockable Disconnect Switch. KiloWatt thieves or no KiloWatt thieves, every HPWC deserves this treatment. Nice!!

    And every EVSE as well.
    --
     
  12. FlasherZ

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

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    It's hard to say. Give what I see of slack, I'm not sure how he's going to get it to connect into the HPWC's terminals with that short cable and leave anything to work with.

    (That bend actually looks like the "end bend" in Romex spools...)
     
  13. ElectricTundra

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    It does look like that and about as sharp of a bend. But it's off the middle of a spool. He did have it connected to the HPWC so it works mechanically.
     
  14. DMC-Orangeville

    DMC-Orangeville 85D and John Deere 5100E

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  15. llavalle

    llavalle Member

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    Yep, the breaker in the main panel, the lugs in the sub panel, the breaker in the subpanel and the disconnect are all rated CU/AL. As for the paste, I'm pretty sure the Canadian code only requires it if you join copper and aluminium or if using stranded aluminium wires - article 12-118(2)
     
  16. wk057

    wk057 Senior Tinkerer

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    There are bend radius rules in the NEC, and as FlasherZ mentioned would be tight in a 2x4 studded wall and potentially unsafe (edge would be near the drywall on the opposite side and subject to potential penetration by a nail from the other side). I decided not to feed my HPWC from the back for many reasons, bend radius being a main one.

    That said, the bend in your photo is definitely not large enough to possibly be the 3.25" radius required by the NEC, almost for sure. Whether that makes it unsafe or not, I generally side with the code on these things. However.... I've seen much worse and doubt you'll have a problem.

    Also, I haven't seen it mentioned here, but keep in mind that with the 6/3 NM cable being used here you can only run the HPWC at 40A from a 50A breaker and *must* set the DIP switches inside accordingly to prevent over-current. I'm sure you're aware, but just in case your electrician has for some reason said otherwise I figure I'd mention.
     
  17. DMC-Orangeville

    DMC-Orangeville 85D and John Deere 5100E

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    Yes, and the cable in the picture is stranded (I used to work for Alcan Cable, the manufacturer of that wire). Most cable larger than 10 AWG is stranded - to ease in bending, pulling and terminating. The paste just insures a clean connection, aluminium oxide is non-conductive. BTW, nice to see you looked up the CEC. I don't have my code book here, but that's basically what it says......
     
  18. llavalle

    llavalle Member

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    Correct, I just looked at a left over cable. I'll check if the electrician installed the paste. Good catch.

    Edit : and thanks!
     
  19. brucet999

    brucet999 Active Member

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    Did he cut off the ground wire?
     
  20. llavalle

    llavalle Member

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    Well well well... Turns out the 270 bend was not a gread idea. The red wire (mine) was pinching the small purple signal wire against the exposed part of the 240V cable that gets to the car.

    The Self test ran fine but closing the cover pinched the wire. Plugging the car in (got my car a few days ago) resulted in a fault in the dashboard and red-right : "Cable Fault, check charger manual".

    Now what I did after that is what you should not do : I decided to run a self-test on the HPWC. When the self-test closed the contactor, it shorted the circuit board and poof! Circuit board is burned and I needed a new HPWC.

    This is clearly not Tesla's fault (my installer is responsible for that) but I do find the routing of the 2 small signal wires to be a bit "at risk". We re-used the loops in my new HPWC but we re-routed the signal wires AWAY from the exposed part of the 240V wires.

    Any one needs a HPWC with a blown PCB ? :D
     

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