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Options for installing 14-50 with apparently full panel

Discussion in 'Charging Standards and Infrastructure' started by arathald, Jul 11, 2018.

  1. arathald

    arathald Member

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    I'm working on getting quotes from local electricians on installing a 14-50 outlet. I'm working off a pretty full panel. Fortunately, there's already a 5-20 outlet in the garage on a dedicated breaker that my landlord has authorized me to repurpose for the 14-50.

    I've included a photo of my panel. The circuit that can be repurposed is the top of slot 10, labeled "Vaccum". My understanding it that two of the circuits (7 and 9) could reasonably be replaced with a tandem pair, leaving room for a 50A breaker on what's currently the vacuum circuit (though this may require upgrading the master breaker, at 100A now). However, at least one of the electricians is saying that the panel is full and would have to be replaced, which is a much more expensive job than just reorganizing the current panel.

    I'm pretty familiar with electrical work and house wiring, but not with the internal workings of a breaker panel. Am I misunderstanding how tandem breakers can be used/swapped in, or should this be possible without requiring an entire panel replacement?

    IMG_2125.jpg
     
  2. kev1n

    kev1n Member

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    yes you can reorganize those, they also have slim breakers now that you can buy. you will probably need new wiring for the 14-50

    100 should be fine since you will do most of your charging at night so there shouldnt be much load during that time.
     
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  3. arathald

    arathald Member

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    Yeah, the slim breakers are what I was referring to with tandem breakers. I do expect they'll need to rewire from the panel to the outlet for the 14-50, but given that it's about 25ft total and there should already be conduit running to the current outlet, that it'll be a relatively simple job compared to wiring up a brand new box/outlet.
     
  4. kev1n

    kev1n Member

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    be persistent that you dont want a new panel or take your business else where. 6 gauge is pretty thick depending on what kind of conduit you currently have sitting there
     
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  5. arathald

    arathald Member

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    Will do. I've only heard back from one company (planning on getting 3 quotes), and they said they'd need to send someone out to look at replacing the panel. I'll talk over my options with whoever they send out and make sure I'm not getting stuck with a much more expensive job than is needed.

    Thanks!
     
  6. PV-EV

    PV-EV Member

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    Assuming you have the capacity...Replace the two full size 15 amp breakers with a tandem 15-50-15 that looks just like the bottom right breaker, but a 50 two pole in the middle instead of the 30. If the conduit to your receptacle is 3/4 EMT you are golden. The breaker is HOMT 1515250CP. Use two black (or red, or one black one red) #6THHN, one #6THHN white and a #10 Green THHN ground. The white neutral won’t be used electrically by the car but is required for the 14-50 receptacle. If the receptacle is 25’ away this is an easy two hour job and $100 in materials. You could easily DIY. If the conduit is 1/2” you will need to run new.
     
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  7. tpham07

    tpham07 Active Member

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    My parents had the same issue as you in their 70 year old house and I thought they would need a new panel too until I discover you can combine the two circuits into those life-saving tandem breakers :)
     
  8. arathald

    arathald Member

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    I rent, so DIY isn't an option, but good to know it shouldn't be a complicated job (depending on what the existing wiring/conduit look like), thanks!
     
  9. nwdiver

    nwdiver Active Member

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    If more extensive upgrades are required for a 14-50 might be worth doing a cost benefit on a 6-20 or other lower power outlet. A 6-20 adapter is available from Tesla for ~$35. 16A @ ~240v should still be plenty to get a full charge overnight.... I rarely charge faster than ~20A...

    OR try to get your landlord to split the cost...
     
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  10. eprosenx

    eprosenx Active Member

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    So this is actually really tough since the panel is so small and already has a lot of doubled up breakers, but it may be doable. At least the panel is modern and appears to be in good shape from the outside.

    So the top breaker on both sides (12 and 11) can't be doubled up since they are AFCI and I don't think they make those in the doubled up form factor.

    Breaker 9 has a lockoff handle on it which I don't think you can do with doubled up breakers either.

    So I only see a single possible option here:

    HOMT1515250CP

    Square D Homeline (2) 15 Amp Single-Pole (1) 50 Amp 2-Pole Quad Tandem Circuit Breaker-HOMT1515250CP - The Home Depot

    Go buy that breaker and replace 9 and 7 with it. That will give you the new 50a 240v circuit, plus replace the existing 15a breakers. To be fully code compliant you would need to provide an alternate locking disconnect means for the dishwasher, but that could be as simple as a light switch under the sink with a locking handle installed over it I think.

    This of course assumes the load calc's on the 100a service feed work out, but hopefully they will!

    As others have mentioned, you could also do a 30a receptacle (with the right corresponding breaker) if 50a is too much for that panel (I would prefer to just crank it down in software though if given the option - this does not pass muster with NEC but it is a nice option).
     
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  11. eprosenx

    eprosenx Active Member

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    Also, you must explain how/why you have a dumbwaiter! Also, why is it off and taped out? Inquiring minds want to know!!! ;-)
     
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  12. arathald

    arathald Member

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    The house was built with a dumbwaiter from the garage (1F) up to the kitchen (3F). Apparently, it has a tendency to get stuck, so it's been disconnected with the car up in the kitchen. I use it as my liquor cabinet :)

    My landlord wants to keep that circuit in case they ever decide to fix it.
     
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  13. arathald

    arathald Member

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    The electrician came out to see the panel this morning. They're comfortable getting me a NEMA 14-50 outlet on a 40A circuit with just rearranging what I've got in the panel now. They quoted me $850, which includes $150 for permitting.

    I did contact two other electricians for quotes, but never heard back from them, even after poking them again.

    Talking to my landlord now to see if he's willing to chip in for part of this and to approve scheduling the work.
     
  14. eprosenx

    eprosenx Active Member

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    Hrm, I am not sure why it would make sense to do a 40a breaker on a 50a receptacle. Your UMC will only be 32a regardless of if you install a 50a breaker or a 40a breaker. So I would just wire it with wire that has sufficient ampacity for 50a and do the 50a breaker. I guess maybe they are worried about someone plugging in something later that draws 40a continuous (which needs a 50a circuit). But in that case, you would be relying on the 40a breaker eventually blowing vs. perhaps depending on other loads in the house blowing the 100a main breaker.

    Basically I just don't get the logic of installing a 40a breaker when it has no functional difference (unless the goal is to allow using cheaper and easier to handle #8awg wire instead of #6).

    If current concerns were really the factor here, then I would do a 30a 14-30 receptacle on a 30a circuit (with the appropriate Tesla adapter). This would limit the UMC to 24 amps of draw.

    I would push for a 50a breaker with wire of sufficient ampacity for 50a. My understanding of the NEC load calcs is that you use the nameplate value of the UMC in either case which is the same regardless of breaker size.

    Also, $850 seems expensive. Is it a pretty long wiring run?
     
  15. arathald

    arathald Member

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    I'd rather get 40A than 30A. Since I'll only be drawing 32A off it anyway, I'm not sure why I should care if they install a 40A or 50A breaker if everything else is equal (including using a NEMA 14-50 outlet, which means I don't need to buy a new adapter). The electrician said that it was the most he was comfortable installing without a panel upgrade, and since it doesn't really make a difference to me, I didn't really question that. It might make sense if Tesla releases an adapter that will draw the full 40A, to make sure I'm still not overloading the panel and tripping the entire house breaker.

    As for the cost, there's a $216 permitting fee included, so their charge is $634, and my landlord agreed to pay for $300 of it. I know it's a little steep for a simple job, and I could negotiate or get other quotes, but I've gotten so frustrated at other electricians not calling or emailing me back that I gave up on them. I'm fine potentially paying a little more for a company that is putting in at least a little effort to earn my business.
     
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  16. nwdiver

    nwdiver Active Member

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    $634 isn't bad; I'm curious to what your electrician is basing his reluctance at installing a 50A breaker vs a 40A breaker. The sum of breakers in most panels is easily >2.5x the ampacity of the bus. 10A seems fairly negligible.
     
  17. arathald

    arathald Member

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    That's a good point. I may ask him out of curiosity when he comes to do the install.Even if I could pull the full 40A, I'm close enough to work to walk, and I get by alright on a NEMA 5-15 right now, so I honestly just don't care enough to try to convince them.
     
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  18. brkaus

    brkaus Active Member

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    If your close enough to walk, you might consider a 6-20. Might be able to use the existing wires in the wall.

    Anyway, sounds like you have it under control. I'm not a fan of the 40a breaker on a 50a outlet, but it is legal. Assume they are pulling new wire. Ask that they use wire that could handle 50A. Read the Tesla manual. I believe it specifies 6ga wiring. If they do the 40a breaker, do label the outlet.
     
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  19. eprosenx

    eprosenx Active Member

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    Yes. Agreed. I would ask them to wire this with 6 gauge wire. At least that way someone could swap it to a 50a breaker later if needed. Technically they could get away with only using 8 gauge wire on a 40a circuit.

    Of course this is not your own place so perhaps you don't care, but for spending that amount of money I would make sure to get 6 gauge.
     

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