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NEMA 14-50 cable / conduit size question

Discussion in 'Model 3: Battery & Charging' started by jeffco98, Aug 12, 2018.

  1. jeffco98

    jeffco98 Member

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    Hi All,
    I'm trying to install a 14-50 outside in my driveway mounted right to the side of my house.
    It'll be 20 feet from my main panel that has 100amp service.

    When the UMC install guide references AWG 6 are they referring to the type of cable linked here ?
    Southwire 50 ft. 6/3 Stranded Romex SIMpull CU NM-B W/G Wire-63950032 - The Home Depot

    Also, what type / size of conduit do I need to use to go through the wall, out to the side of my house ?

    Thanks in advance. Really love reading this forum.
    Jeff
    Waiting an my Model 3
     
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  2. SSedan

    SSedan Member

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    I don't think you are supposed to use Romex in conduit.
    You can buy THHN by the foot at Home Depot.
    Take pictures of your situation and go talk to the licensed electrician at Home Depot. In my experience they are very helpful.
     
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  3. jeffco98

    jeffco98 Member

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    thank you
    Can I run the Romex right through the wall directly into an outdoor 14-50 outlet.
     
  4. iluvmacs

    iluvmacs Member

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    Hate to say it, but this falls in the category of "if you don't know, hire it done".
     
  5. FlatSix911

    FlatSix911 918 Hybrid

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    Here is a great FAQ ... :cool: FAQ: Home Tesla charging infrastructure Q&A

    WHAT WIRE SIZES SHOULD BE USED FOR INSTALLING MY NEMA 14-50R? Note: All wire sizes assume copper conductors!

    For wire-in-conduit, 8 AWG THHN (dry locations) or THWN (wet locations) is sufficient to carry 50 amps, but many electricians will use 6 AWG to ensure that there is enough headroom. The ground conductor must be a minimum size of 10 AWG.

    For “Romex” (NM-B cable), it must be sized for the 60 degC rating. This means that 8/3+ground NM-B may not be used for 50A, and 6/3+ground NM-B must be used. Note that type NM cable must be protected from damage (e.g., must be run inside a wall) and cannot be exposed. If you must run wiring on the outside of a wall, below 7' above the floor, you must use conduit. Type NM cable may be run in conduit as long as it does not run outside. If these conductors will ride in the same conduit as another circuit, they must be “de-rated” and 6 AWG is required.
     
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  6. eprosenx

    eprosenx Member

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    Yes, 6/3 copper NM-B is common for 14-50 circuits. It just can't be run exposed (I think there are exceptions as mentioned by others, like if above 7' off the ground?).

    Romex in conduit is allowed, but there are rules around it and it is in most cases not great practice. THHN/THWN is much more common in conduit. I think one of the limitations is perhaps that it is not rated for wet locations and even things in conduit outside I think are considered wet.

    Yeah, so I stressed over this for my HPWC installation and I went ahead and did a 6" Rigid piece of threaded conduit that I bought pre-made at Home Depot and then I transitioned to EMT inside the garage on the exposed wall. So when the inspector came out he told me he would have been just fine with Romex penetrating the wall directly into the back of the HPWC. Needing to penetrate the wall with things is very common and so they are OK with it being NM style cable I guess as long as it does not run for any distance outside. I guess I would be really careful to seal up the back of the 14-50 waterproof box or the HPWC depending on what you are installing.

    For my generator transfer panel (which I installed at the same time) I ran through the wall with EMT with a water-tight fitting on the outside end of it. This worked quite well. I could not do that with the HPWC since the back side of the HPWC is threaded vs. the unthreaded metal punch out on the power inlet receptacle for my generator. No good way to spin the conduit into the HPWC when I also need a 90 degree elbow on the other end of that short piece of conduit to then make it flush with the wall.

    You can absolutely tell that the Tesla stuff is not designed by electricians that actually work in the field. Install of some of their stuff is a bit annoying.
     
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  7. nwdiver

    nwdiver Active Member

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    I didn't know how to cook chicken at one point... should the fear of food poisoning and burning my house down have made me keep going out for dinner?
     
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  8. flashflooder

    flashflooder Member

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    This is false. Romex is fine in conduit.
     
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  9. iluvmacs

    iluvmacs Member

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    Is it possible for you to cook it in such a way that your house burns down a few years later?
    If you put the chicken in the wrong type of pan, could it explode?
    Do most people that cook chicken have professional training and a license to do so?
    Are there permits required for cooking chicken?
    And finally, did you ask the Internet how to do it, despite the fact that you have no idea how to even turn on the stove?
     
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  10. bkmartin

    bkmartin Member

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    I'm not an electrician, but I have seen around my house where I have outdoor lights and outdoor receptacles, romex is run directly into those fixtures (I know because I have replaced some of the fixtures). I think what you are saying makes sense and the same would apply to an HPWC. It seems the easy option here is to ask the city inspector before you install it to see what is required in your municipality. They probably even have an email address you can write.
     
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  11. SSedan

    SSedan Member

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    I tried to do some reading on romex in conduit and it is confusing enough to just say the heck with it and do THHN THWN. On further reflection yeah there has to be cases it can be done because some romex style cable is burial rate and I am sure needs protection where it goes into the ground and comes back up.

    The 8gauge wire you would need is $0.56 a foot for simplicity say you use that for all 4 wires not downsizing the ground and round up to 25ft from your proposed 20ft run. That is $56 worth of wire which leaves plenty of savings to buy conduit. 6/3 by the foot is $3.68 and solid wire. Don't see a price for 6/3 stranded by the foot online.

    Far as "if you have to ask" can't imagine going thru life having learned all I need to know in kindergarden;);)
    Licensing is good for those getting paid to do work because it hopefully guarantees some accountability, but very often licensing agencies are self serving there first to make a buck for themselves.

    "Professional" very very often means "gets paid to do" which has relatively little to do with how knowledgeable, thoughtful and quality minded someone is.

    In construction trades especially a great many of those involved are looking at absolute cheap/fast as possible to maximize profit. I had a contractor move a service door from where I planned it to be next to the overhead because the beam across the overhead would have had to be longer and those are $7 a foot, so he put the door on the wrong wall 6ft. from where I wanted it to save $42 on a $25k project. That is the construction mindset that is the the way most but not all construction tradespeople work. You are unlikely to know who is who either since most customers don't know enough to evaluate and give feedback. Over the years I have dealt with enough people who built good reputations based on customer ignorance to be cautious.
     
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  12. nwdiver

    nwdiver Active Member

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    #12 nwdiver, Aug 13, 2018
    Last edited: Aug 13, 2018
    Stay safe out there...



    Snarky comments aside the fact is that wiring a 14-50 outlet probably doesn't even rank in the top 10 of hazardous and complex things the average person does; It's not hard or complicated; If you don't know... look it up.

    It's nothing to be a afraid of. Remember; Fear leads to Anger, Anger leads to Hate, Hate leads to Suffering <(-_-)> ..... ;)

    EXACTLY! I'd love to see stats but I really think the DIY'r that took the time to research what they were doing does a better job on average than a 'pro'. I've fixed so many boneheaded mistakes that professional electricians have done....
     
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  13. jeffco98

    jeffco98 Member

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    Thanks for all the input.
    As luck would have it an electrician finally returned my call and will be over this week to take a look.
    He tells me that he's getting tons of calls for EV chargers, and had more questions for me, than I had for him (regarding EV's not electrical work)
     
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  14. rhumbliner

    rhumbliner Member

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    Depends upon the individual. I'm not an electrician (software engineer) but I enjoy taking on these projects myself and learning something in the process. My latest project was to run 100-amp service to my attached garage.

    This involved:
    1) removing my 200-amp meter box and replacing it with a 300-amp meter (which required a visit from my local utility);
    2) adding a 100-amp cutoff breaker next to the meter;
    3) running 60' of conduit & wire from the new cutoff breaker to the garage;
    4) installing a 100-amp sub-panel inside the garage;
    5) running conduit & wire from the sub-panel to my HPWC;

    Time spent on the actual work, I'd estimate at 24 man-hrs over 1 week. Time spent planning, I'd estimate at 20 man-hrs over 4 weeks. Since I had never tackled this large a project before I was very careful to think all the steps thru. To be fair, these estimates ignore all the time spent driving back and forth to my nearest electrical supply shop to gather parts & supplies. :oops:

    I also spent time discussing this with the electrical engineer at my local utility (he recommended the 300-amp meter) and I visited my local fire inspector to get his tentative approval before I began the actual work. The inspector's suggestions were invaluable and as a result, when he came to review my work it was approved on my first try.

    My advice is, if you're willing to invest the time & energy and you enjoy DIY projects then this is all doable. Most importantly, take out a permit for all work and have the approval before you energize anything.
     
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  15. nwdiver

    nwdiver Active Member

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    Just don't rely on the permitting process to ensure the install is correct. In many places that's just income for the city....
     
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  16. iluvmacs

    iluvmacs Member

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    Completely agree. I'm a computer engineer that also does some home electrical work, including having installed several EVSEs. But when I start a project, I research things by actually reading the NEC and talking with knowledgeable people, not just asking the Internet a question with no thought process that makes it look like I know what I'm doing but just need a quick tip. It's incredible the number of posts that are just like "what wire size should I use for 50A?" when that's clearly in an NEC table, or bad advice on what breaker to use with a certain receptacle. Those are the installs that go wrong and cause fires, not the ones that you or I do.
     
  17. nwdiver

    nwdiver Active Member

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    #17 nwdiver, Aug 13, 2018
    Last edited: Aug 13, 2018
    If you've never done this before an internet post could be how you find out about the NEC table.... which is also on the internet. Definitely silly to use information you get from a thread to install a 14-50... but it can be a good STARTING point.

    My first solar PV install was challenging but you've gotta start somewhere. If I had been more active on a forum like that that would have saved me a lot of time trying to find the right resources... and I probably would have asked a ton of 'dumb' questions...
     
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  18. Swampgator

    Swampgator Member

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    6/3-4 Romex is fine in 3/4" PVC electrical conduit at a 40 amp load.
     
  19. FlatSix911

    FlatSix911 918 Hybrid

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    More FUD... Fear, uncertainty and doubt - Wikipedia :cool:
     
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  20. David99

    David99 Active Member

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    Personally I would always oversize wiring. Just to keep the losses lower. Normal wiring rarely gets used a lot. Charging an EV is different. We are pushing a lot of energy through the wire and we do it for many hours every day. The losses do add up. I have charged 35,000 kWh at home in the last 4 years.
     
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