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Only 198 volts on nema 14-50. Yikes!?

Discussion in 'Model 3: Battery & Charging' started by DavidM34Me, Oct 4, 2019.

  1. DavidM34Me

    DavidM34Me Member

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    My electrician just installed a Nema 14-50 in my garage. He used 6/3 NMD90 wire on a 50 amp breaker. The run is about 120 feet. The car is charging at a full 32 A, but the voltage is only 198 V. I knew there might be some small degradation given the length of the run, but less than 200 volts is of concern to me. Is there something wrong here?
     

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  2. Timbo2

    Timbo2 Member

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    Maybe. It depends. When I first moved to my house the antiquated infrastructure that served my house was subject to lots of brown outs and power interruptions. My voltage is better now, but others here do much better.

    Do you know what your voltage usually is? And can you measure it on another circuit? Can you measure this circuit when it isn't under load?
     
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  3. gaM3changer

    gaM3changer Member

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    What’s the reported voltage when you manually lower the current from inside the car?
     
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  4. qdeathstar

    qdeathstar Active Member

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    There is definitely a problem. What the problem is, who knows. I would ask your electrician to do a double check on his end. It might not be his fault but there is an issue. A reputable electrician shouldn’t mind helping you out.

    -A reputable electrician
     
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  5. M3BlueGeorgia

    M3BlueGeorgia Active Member

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    This is key advice. Disconnect for 30 mins then drop the amperage by half and see if the voltage recovers. If so, you have a problem in your house.

    Until you get the issue fixed, keep the amperage lower than 32A, to whatever is safe. Start with 24A, but be prepared to go lower.
     
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  6. El0n

    El0n Member

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    Pardon my ignorance.

    I also have a level 2 like OP.

    The volt is usually 198-199 when charging. The amps start at 6/6 and then after 2-3 minutes goes to 32/32 A.

    I didn’t realize the volt below 200 is an issue? Can someone please help and educate?

    Thank you in advance.
     
  7. M3BlueGeorgia

    M3BlueGeorgia Active Member

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    Same question I posed the other person. If you limit your amps to (say) 16, what voltage do you see?

    Some people are on a commercial connection and won't see more than 208v. Most households will see around 240v.
    If you get around 240v with a low amperage, you have an electrical issue and should limit your amperage until fixed.
     
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  8. DavidM34Me

    DavidM34Me Member

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    I dropped the amperage down to 16A. The voltage rose to 204v. At 6A it was 205v.
     
  9. gaM3changer

    gaM3changer Member

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    The voltage drop to <200V is only a concern if you’re running on a 240V circuit. If you’re on 208V, then what you’re seeing is within tolerance.

    In general, a high voltage drop can be caused by things like a loose connection, long wires or wires that are too thin. This can be dangerous because of the chance of fire due to overheating of the wires or charging equipment.
     
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  10. gaM3changer

    gaM3changer Member

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    #10 gaM3changer, Oct 4, 2019
    Last edited: Oct 4, 2019
    Are you sure you’re not on 208V service?
     
  11. DavidM34Me

    DavidM34Me Member

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    It’s a new house in Toronto so I doubt it.
     
  12. El0n

    El0n Member

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    I am in a condo building and the wires from the main electrical box run about 300 feet to get to the commercial EV charging stations

    So is volts like resistance?

    Any resources I can read so I can understand amps, volts, watts, and all of the electrical stuff?

    Mainly for my own education. Thanks.
     
  13. gaM3changer

    gaM3changer Member

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    #13 gaM3changer, Oct 4, 2019
    Last edited: Oct 4, 2019
    Ohm’s Law: V = I x R
    P = V x I
    Where V = voltage, I = current (A), R = resistance (Ohms) and P = power (W)atts

    Sorry, I’m on mobile so I can’t get links at the moment.
     
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  14. gilscales

    gilscales Active Member

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    Could be a bad transformer at the pole.

    I recently had a problem at a place I own with 3 single family detached homes on a lot, one of the tenants called to complain about some items not working right and my electrician found 198V on one leg and 220V on the other leg.

    SCE came out and said they fixed the problem without telling us what it was.

    More complaints and another check shows the same problem, it took SCE maybe 2 months to admit they needed to change out a bad transformer, all 3 houses noticed things working better after and electric bills going down.
     
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  15. DavidM34Me

    DavidM34Me Member

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    I’m told it’s 220v in Toronto where I am. The run is about 120-130’. 6/3 NMD90 wire. Do you think this is something to be concerned about?
     
  16. ucmndd

    ucmndd Well-Known Member

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    #16 ucmndd, Oct 4, 2019
    Last edited: Oct 4, 2019
    New single family home?

    Per another thread that came up in a quick search, there are at least some areas in Toronto still providing split phase 208v residential service:

    Unusual home voltage

    The only way to really determine if you’ve got a problem is to measure the voltage at your mains and verify with your utility what the expected nominal voltage is in your neighborhood.

    If it’s 208 you’re fine. If it’s 240 (nowhere in North America uses 220v, this is a common misnomer) and you’re still only coming up to ~205v at 6 amps, don’t use that outlet at all until someone checks it out.

    My money is on your house having 208v service.
     
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  17. gaM3changer

    gaM3changer Member

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    From my quick google search, Canada has 120V, 208V, 240V, 480V and 347/600V. Assuming you are on 240V, then you’re seeing almost 18% voltage drop. For a 120’ run in ideal conditions, you should only be seeing <5% drop.

    I’d stop charging from this outlet until you get an electrician to come check it out or confirm that it is indeed 208V.
     
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  18. dhanson865

    dhanson865 Active Member

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    #18 dhanson865, Oct 4, 2019
    Last edited: Oct 4, 2019
    ANSI C84.1 Service Voltage Limits

    Ø Range A minimum voltage is 95% of nominal voltage
    Ø Range A maximum voltage is 105% of nominal voltage

    If your home service is 240v (which it should be in all of North America) that is outside of specs. Time to check the plug, wiring, breaker, mains, etc how ever far back the chain it takes to find the voltage drop.

    If and only if you can confirm the voltage outside your main box is 220v or 208v you can ignore it, but for residential it should be 240v inside the house and 250v out on the lines.
     
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  19. dhanson865

    dhanson865 Active Member

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    #19 dhanson865, Oct 4, 2019
    Last edited: Oct 4, 2019
    no such thing as 220v service in North America and hasn't been since well into the prior century. It's either 240v and you have an issue or it's 208v and you are OK.

    The Canadian standard is CAN3-C235-83.

    hmm, looking at some PDFs

    upload_2019-10-5_0-20-30.png

    it seems the Canadian standard still allows for service at a home in 220v. But I know from the interconnect standards you can't send that around from region to region so I'd be surprised if any 220v still existed.

    I'd darn sure want to be certain what my main supply into the house was before I made any sort of evaluation on safety to charge there.
     
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  20. qdeathstar

    qdeathstar Active Member

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    200 volts is a serious voltage drop. It indicates a loose connection or under sized wire, both of which are a serious fire hazard.

    it is also possible you have an issue with your utility source or the measurement on the car end but it definitely needs to get checked...
     

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