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Can i put a 14-50 ? I only have a 100 Amp 240 volt incoming to condo.

Discussion in 'Model S: Battery & Charging' started by Vincent Himpe, Oct 16, 2013.

  1. Vincent Himpe

    Vincent Himpe Member

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    Location:
    San Jose, California, United States
    Here is my problem :
    I live in a condo and have my own garage. The HOA is ok with me installing a power outlet and fuse (nema 14-50) provided it is done with a permit by a licenced electrician. Even though the garage is for my exclusive usage only it is considered common property.
    Here is the problem : the Main breaker for my unit sits in the shared utility closet. This is a 240 volt 100 amp circuit.
    the panel is shared with 7 units and is a 1200 amp panel.

    According to the NEC and California electric code a load calculation is in order to figure out if the 50 amp fuse and Nema 14-50 can be installed or not.
    And this is where the misery begins...
    i can't make heads nor tails from this calculation and get a lot of conflicting information.

    Every major appliance in the house is GAS apart from an oven in the kitchen.
    Here is my fuse box breakdown
    15 amp : hallway / entry/ living room
    20 amp : FAU (furnace and air handler)
    20 amp dining area
    20 amp microwave
    20 am kitchen gfi 1
    20 amp kitchen gfi
    20 amp garage gfi
    20 amp house gfi (bathrooms)
    15 amp bedroom 3
    15 amp master bedroom
    15 amp bedroom 2
    15 amp entry and stairwell
    30 amp 240 volt for Oven ( two linked fuses 30 amp each )
    20 amp garabge disposal
    20 amp dishwasher
    40 amp AC 240 volt ( 2 linked fuses )
    20 amp laundry
    20 amp laundry

    i have the real appliance power rating:
    microwave 1650watt
    oven : 2700 + 3600 watt
    dishwasher : 10.5 ampere
    clothes washer : 10 ampere
    clothes dryer : 6 ampere

    can someone figure this one out ?
    i did a couple of excercises and always end up around 24000VA ( sometimes 100 Va below, sometimes 300 Va above )

    Thanks
     
  2. Chris TX

    Chris TX Active Member

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    First off, don't be scared.

    If you add all those breakers up, you get 365A which is way over 100A.
    I said not to be scared, right? ;)

    Now, if you rate all that at 80% load (continuous is 3+ hours), you get 292A, which is still way over 100A.
    We're still not scared, right?

    It looks like all those appliances running at once AND at full power will pull just slightly under 70A. Nevermind the lights, TV, Air Conditioner, ceiling fans, fish tank, hair dryer, massage chair, etc.
    Keep with me here: Breathe deeply.


    The first thing you need to do is analyze how you use your electricity.
    -How often do you use each of those high-ish amp devices?
    -How often do you use them simultaneously?
    -Do you have a way to see what your electricity usage is during the day, either real time or nice pretty line graphs that show peak usages? Most companies that utilize e-meters let you look at historical energy usages.

    The third option is ideal because it will show you what your maximum kWh usage is. Take that maximum and divide by 230 to get your amps. If you have 40A leftover, or say ~8 hours at night where you can squeeze in 40A worth of load, you should be fine.

    If you can't find a 6-8 hour window with 40A to spare, you can always lower the charge amps on the Model S to draw less power from the 50A outlet and/or only charge during certain hours of the day.

    Lastly, just make sure you have a two-breaker spot in the box ready for a 2-pole 50A breaker. It also makes things cheaper if you can buy the outlet, breaker, and 6-3 (or 8-3 if it's a short run) wire on your own so the contractor doesn't mark it way up.

    Best of luck!
     
  3. islandbayy

    islandbayy Active Member

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    My personal opinion (and I deal with a lot of electrical, though not licensed electrician), is that you should be "fine" for a NEMA 14-50 if used strictly during off-peak hours for your own usage (And really watch your loads). Example, the hours that you use the least amount of power. THOUGH, while you should be fine. I always err on the side of safety, especially when dealing with electricity. I would personally, with a 100 amp breaker, go with a NEMA 14-30 instead. A 14-30 will have a continous load rating of 24 amps. 24 amps is more then enough to charge my fully depleted 60kw battery overnight. No room to spare though, but it would do it. I am in the group of people that drive excessively (IE, as of Today, I've had my car 5 months to the day, and I will be hitting 13,000 miles today). I do have a 14-50, but I upgraded my service drop from 100 amp to 200 amp.


    Now, question. Why can't you upgrade your service to say, 150 or 200 amps? It seems their is extra capacity at the service panel where power is split between the condo's. Unless your breaker box is a great distance from the panel, should not cost very much, and you would be in much better shape then you are now.
     
  4. linkster

    linkster Member

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    #4 linkster, Oct 16, 2013
    Last edited: Oct 16, 2013
    I tend to agree with "islandbayy". Do you have a typical commute so that you can roughly predict your daily electrical needs for your "S"? You have several options. You can charge 40A at night while your condo is not requiring much electricity. You can always dial your amps down to less than 40A if you need to charge during the day just to be safe. Our commute is 80 miles/day and we only use a NEMA 10-30 for 4.5 hrs of charge time starting at 1:00am (our electric rate drops by 50% starting at 1:00am). I am a firm believer in owning most or all of Teslas available adapters, with that being said, you can save money on wire if you have a long run to the panel by running a 2-wire (2 hots, 1 bare ground for a 10-30 or 6-50) instead of a 3-wire (2 hots, 1 bare ground, 1 neutral for a 14-30 or 14-50). The neutral wire is useless for charging EV's. Even the relatively new Tesla 5-20 115v adapter will give you a 5mph charge rate.
     
  5. drees

    drees Active Member

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    With an A/C unit that requires a 40A breaker and an electric oven (30A breaker), it is highly unlikely you'll be able to install a NEMA 14-50 on a 50A breaker with a proper load analysis.

    Here's a good article that goes over the calculations (both Standard and Optional methods):
    Residential Service Calculations in the National Electrical Code - International Association of Electrical Inspectors (IAEI)

    If you are planning on having an electrician do the work - they should do the load calcs, pull the permits and everything for you.
     
  6. David_Cary

    David_Cary Member

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    I'm with Drees - while you could regulate your peak, code won't allow you to do that.

    That is an incredible amount of things on a 100 amp panel.

    Now if you are willing to give up your a/c or electric oven, then you could conceivably do it.

    EVs aren't great for condo/apartment/street parking in 2013 and for the foreseeable future. IMO - you are going to have to get a new panel/line to make this work.
     
  7. dhrivnak

    dhrivnak Active Member

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    Since you CAN control the car it can work. Just do not run the A/C, cook and charge at the same time. Set the car to charge AFTER you are done with the stove/oven and you will likely be fine. Getting an electrician to install may be difficult but if you can wire it yourself then all is good. It is not too hard to wire and I did mine myself.
     
  8. Vincent Himpe

    Vincent Himpe Member

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    Hold it. maybe i wasn't clear enough.

    From a pure technical perspective i can do it. if i program the car to commence charging at 10 PM and terminate before 6AM there is no TECHNICAL reason it woudlnt work.
    40 amps drawn by the car , 30 amps to run HVAC and 10 amps vampire draw for things like clockradio and tv and lights. Come 9PM i am asleep anyway.
    gives me 20 amps margin on my feed.

    that is NOT the issue.

    The issue is that , since this is a condo , and the outlet is in the COMMON area a PERMIT is MANDATORY.
    the PERMIT is the problem. they will do a load calculation. This is the part i can;t figure out. i'm trying to assess if this will pass or fail.
    i don't want to end up in the situation where the work gets done , the inspector comes and refuses to sign off ...

    upgrading service is IMPOSSIBLE. that avenue has been explored. the distance between the 100 amps mains fuse ( in the meterpanel ) and my fusebox is long and fed by an underground cable running under the building... there is no way to pull another cable. i am stuck with the 100 amp service.
    I am an electronic engineer myself . i just don't have experience with the convoluted NEC.

    So. the question is : can someone explain me how to do the load calculation so i can get an idea if it is

    -not doable at all
    - maybe doable but needs assement from an electrician with experience.
    - not a problem

    before i contact electricians for bids.

    the actual work is very simple. install an outlet directly beneath the fusebox. no visible conduits or cables. make a hole 1 foot below , install box , run 2 feet of cable , install breaker . done.
    it's the permit i am afraid for.
     
  9. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    The way to address the permit issue is to contact the building inspector and ask.
     
  10. cantdecide

    cantdecide Member

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    That sounds like a painful situation.
    I also wish I understood those codes.

    I wonder how much it would cost to build a device that had an old (not particularly dense) 20kwh battery and a 110volt plug... You leave it in your garage then at night you get 12amps while parked plus a 20kwh boost would be enough for some people in similar situations to you.
     
  11. dhrivnak

    dhrivnak Active Member

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    If you need to get a permit, then I would take a picture of you panel and visit the building inspector and ask. I have found most are very helpful and codes can and do vary. If you can get by without a permit that is your best option. We live in an area with minimal regulation. A fallback would be to install a 30 amp service.
     
  12. montgom626

    montgom626 Active Member

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    Good idea.
     
  13. Apoclyps

    Apoclyps Member

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    Why can't you bring in an electrician to see your layout and ask them if it is feasible.

    In my situation, I live in a condo with just 4 homes connected, each having their own garage. I was lucky that the meter closet was on the outside of my garage (I am on one of the 2 ends). I brought out 3 different electricians for a free quote, and to see if it was feasible for me to charge my car on the existing system. the 3rd electrician basically split from the meter closet, to go to 2 different subpanels, the original one for the house (2nd floor opposite side of house), and a new one for the car in garage.

    BTW, when I went to City Hall to ask for the permit, all they cared about was whether I had a licensed electrician doing the work, and a diagram of all the work that going to be done. They didn't ask about load.
     
  14. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Given your situation, if you can get a 14-30 installed with a 30A breaker, that will still give you a 17 mph charge rate which would work in all but the worst of situations. Even if all you could install is a 6-20 with a 20A breaker, have the electrician make you a 6-20p to 6-50r adapter, set the 16A limit in your MS, and charge at 11 mph, you could probably live with that with a little planning. I'm guessing it would be a lot easier to get a 20A or 30A circuit approved.

    In San Jose, you can probably find a faster charger nearby in a pinch. Can you get your employer to install a 30, 40, 70, or even 80A J1772 at work to help you out?

    Good Luck!
     
  15. linkster

    linkster Member

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    #15 linkster, Oct 17, 2013
    Last edited: Oct 17, 2013
    Like Cottonwoods 6-20 to an adapter approach! You can easily make the adapter yourself or have evseadapters.com make you one. Once you dial down your current to 16A, your smart "S" will remember to only "pull" 16A every time you come home.
     
  16. FlasherZ

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

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    From the information you've given us, it's likely going to hinge upon the nameplate of your A/C unit. Look at its nameplate and use the "minimum ampacity" for your load calculation. Your breaker is sized for startup current on the compressor, but that's not the normal consumption of the unit. Same for the air handler.

    My guess is that you will likely pass a load calculation for a 14-50 as part of the inspection.
     
  17. snake9

    snake9 New Member

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    Good info
     
  18. Vincent Himpe

    Vincent Himpe Member

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    So, i went to the city building planning deivision , got a hold of a permit electrician an d he did the load calculation for me. in short : It can't be done on my 100 amp panel.
    I need to eliminate an appliance. So the oven will have to go and be converted to gas.

    All other pathways are blocked
    My underground cable is 110 amps max and cannot be replaced.
    my main fuse is 100 amp.
    service upgrade not possible

    the load calculation ended up at 88.1 ampere. so even a 20 ampere 240 circuits is not possible.

    however, since my electric oven sits on a 30 ampere 240 volt : if i ditch that one i can charge the car.

    So this is a warning to prospective electric car buyers : check your service and breaker panels first ...
     
  19. Cosmacelf

    Cosmacelf Active Member

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    Well, you do have the option of a 120V NEMA 5-20 giving you about 5 miles/hour of charge. It'll work for now.

    Would the electrician consider installing a transfer switch for the oven?

    OR, for purposes of the permit, disconnect the oven.

    Install the NEMA 14-30.

    Say goodbye to the electrician.

    Reconnect the oven because this is another example of "We're from the government and we're here to help".

    Sheesh.
     
  20. Brian4591

    Brian4591 New Member

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    #20 Brian4591, Oct 18, 2013
    Last edited by a moderator: Oct 19, 2013
    Vincent,

    Get a second opinion. I am a licenced electrical contractor in BC, Canada and the info you have provided would tell me that it is definitely possible to install a charging receptacle.
     

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