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Advice on pre-wiring my Garage

Discussion in 'North America' started by pete8314, Nov 24, 2012.

  1. pete8314

    pete8314 Vendor

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    #1 pete8314, Nov 24, 2012
    Last edited: Nov 24, 2012
    To pass time between now and when my Model S will be delivered some time in the spring, I'm going to redecorate my garage, top to bottom. Before I start on much, I wanted to know if there's anything I can do to get ready for the electrics that my Model S will need.

    Needless to say, by breaker box is on the right-hand side of the garage, so I'll need the charger plugged in on the other side (there's another double garage at 90 degrees to mine, so by moving the charger to the left-side, it opens up options for charging a car in the other garage when that time comes).

    Although I plan on having an electrician make all the connections, they're not usually the best at doing a tidy job (and I'm kinda particular :)), so I'd rather pre-cable as much as I can, so that all they need to do is to connect at the breaker box.

    I assume at one end I should provision for a NEMA 14-50 outlet (I'm not planning on the HPWC), but I'm not sure on the following:

    - What cable should I run?
    - Will my breaker box take the additional load?

    I ask the second question as when I had a pool installed, they had to add an additional breaker box outside for some of the house stuff, and use the main breaker box for the pool. You can see that (50 amp)breaker in the top right of the main (taller) box below. Essentially I can get some extra length on the cable to give the electrician some options, but the cable is expensive, so I don't want to over-buy. The house is relatively new, so I assume there's enough power coming from the street.

    I've added some pictures below to help paint the picture, any advice is welcome - thanks.

    garage front view.jpg
    large box.jpg small box.jpg
    both boxes.jpg
     
  2. bmek

    bmek Member

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    How many amps in your panel?
     
  3. pete8314

    pete8314 Vendor

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    550 on the main panel, 125 on the sub panel, and another 90 on the panel that's part of the pool control (of which 50 is pool stuff, the rest is dryer and one of the lighting circuits).
     
  4. FlasherZ

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

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  5. sublimaze1

    sublimaze1 8Dec2012 / Leeroy Jenkins

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    +1 FlasherZ - but your run can be incredibly short, saving you on the 6/3 cost - if you decide to back in each time. Or not. Your call.

    PM me if you are interested in seeing what I did in my garage.
     
  6. Lloyd

    Lloyd Active Member

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    It might be easier and more cost effective to put a little larger subpanel in the garage allowing a few extra slots rather than running a new feed from the main panel.
     
  7. pete8314

    pete8314 Vendor

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    Here's a pic of the main breaker:

    main breaker.jpg

    There's nothing obvious which shows 200A on the label, or, as far as I can tell, elsewhere on the breaker.

    I really don't want to back in all the time, plus, I want to have the option to charge in the other garage as well. As for surface-mounting, well, I've just spent the last 2 hours hiding the conduit for the sprinkler control, so I'll be putting the cable in the wall :) It's 13ft across the garage, plus, say, 8ft for each drop, and a couple of foot slack, so 25ft should do it.
     
  8. FlasherZ

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

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    It's personal preference, and I can understand your position in a finished garage. :)

    As for the rating of your main breaker, it should be etched into the handle -- it's required to list the trip rating.
     
  9. mitch672

    mitch672 Active Member

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  10. JackA

    JackA Member

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    I would recommend that you consider provisioning a 100 Amp circuit to the new charging location. I am not an electrician but did have one perform the installation in my garage and he used #2 conductor or wire. The reason I put in the capacity for 100 Amps is that I wanted an option for the future. We are only using an NEMA 14-50 outlet now (it is on a 50 Amp breaker with 100 Amp capable wire) If we decide to place a High Power Wall Charger at this location in the future it will require only the installation of the 80 Amp Breaker. The cost to install should be the same and there would be only a few dollars difference in materials cost. You could have the electrician quote both 100 and 50 Amp capable circuits then make your decision.
     
  11. pete8314

    pete8314 Vendor

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    Thanks, will do. I need to get a couple of quotes next, so will see what the difference is.
     
  12. FlasherZ

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

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    The major difference is that a 50A circuit can be placed on type NM-B 6/3 cable, while 100A requires THHN/THWN #3 in a conduit. The wire cost difference is roughly 2x the cost, but you have to figure in the conduit and installation for that conduit. If it is a short run (40' or so) your materials difference may only be $200. But if you're looking at a long run, you could have a significant expense in the different, and then you'll need to consider whether you'll use the high current or not.
     
  13. JackA

    JackA Member

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    pete8314: I would still check this with a licensed electrician familiar with your local code requirements. My entire materials bill was $453. I had 40 feet of conductor in 1 1/2 conduit, 20 feet of wire from the load center to a junction box where it changed to conduit and conductor plus a new sub-panel and the wire and breaker and connectors. I am not thinking that I would have saved very much by installing a 50 Amp circuit.... again, I am not an electrician.
     
  14. teslasguy

    teslasguy MSP P#1117

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    I also ran a 100amp subpanel to my garage and then a NEMA 14-50 outlet off that. This I can now easily run another outlet for my wife should she also get an EV.


    P1117 Sent from my iPhone using Tapatalk
     
  15. FlasherZ

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

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    Your materials bill will be considerably less if you can use NM-B inside a wall. Wire cost is roughly half, plus you save the cost of the conduit. If you can't run inside a wall, Romex must be run inside conduit to protect it, so your only cost difference is the wire cost ($118 for 50' of 6/3 vs. $232 for 200' of #3).

    - - - Updated - - -

    This is a good strategy if you think you'll need an EV at some point. I fed a 125A subpanel from my main panel, and that gives you room for an HPWC @ 80A + a 14-50 @ 40A. But that's because I know I need a high-amp charging solution - the cost differential would be several hundred dollars.

    It's similar to the HPWC vs. 40A charging arguments -- every case is different and if you have the money it doesn't hurt... but for some people it's an extra $300 or so.
     

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