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Switch for Oven/Model X?
- Thread starter shinytop
- Start date
Hank42
Legacy Supporter
Hi Shinytop,
If indeed your panel cannot support the additional 50 amps - a 3 pole double throw safety switch could work.
They are not cheap...
Amazon.com: siemens DTNF322
Shawn
If indeed your panel cannot support the additional 50 amps - a 3 pole double throw safety switch could work.
They are not cheap...
Amazon.com: siemens DTNF322
Shawn
I am retired so commute is not a big deal. My home town is scheduled for a supercharger this year but no sign yet. The nearest superchargers are 6-70 miles away, Mobile and Defuniack Springs.
My panel, I think, is a 125 amp panel so looking at alternatives to changing the panel. Yes, dryer is close to where I need the charging port but a real pain to get to the plug. So that's why I was looking into switch for oven/Nema 14-50. Will have Tesla recommended electrician look at it this week.
Anyone know the lead time to get a 14-50 adapter since I believe they no longer come with the car.
My panel, I think, is a 125 amp panel so looking at alternatives to changing the panel. Yes, dryer is close to where I need the charging port but a real pain to get to the plug. So that's why I was looking into switch for oven/Nema 14-50. Will have Tesla recommended electrician look at it this week.
Anyone know the lead time to get a 14-50 adapter since I believe they no longer come with the car.
Yes. Conceptually very easy to do. Install a small subpanel with two dual pole breakers in it side by side. When you want to use the oven switch the oven breaker on and the charger breaker off and conversely. To simplify and satisfy yourself that you can never have both on at once link the toggles on the breakers so that turning one on turns the other off.
Note that 3 pole breakers are not required here. The neutrals stay connected all the time.
That's conceptually. Looks like the Dryer Buddy is a much more elegant solution.
Watts_Up
Well-Known Member
Yes but a Dryer Buddy is an automatic switch which disconnect the EVSE (Electric Vehicle Supply Equipment) when the Dryer starts,
and reconnect it when the Dryer ends.
I imagine that the OP doesn't uses quite often the oven, so this seems to be an haddock solution.
However, if someone forget to switch back the breaker after using the oven and the car needs to get charged overnight,
well someone will have a big surprise in the morning...
So I would say: That's conceptually. Looks like the Dryer Buddy is a much less practical solution.
Note: I mostly use my oven as a grill, but sometime I use it to bake something.
I always try to remember to put back to grill in that case, but I often forget.
So, the next morning when I try to grill some toasts, only one side is grilled.... and the other side is mochi.
Having trouble following that. If one goes with the breaker solution then he has to take responsibility for flipping the breakers. If he forgets to do that after using the oven then yes, his car will not be charged. And its his fault. A result of his absent mindedness.
With the Dryer Buddy the switchover is automatic. If he is charging the car and turns on the oven charging is suspended until the oven goes off at which point charging resumes. One need remember nothing. This is much more practical. However there may be some other things to consider. An oven cycles on and off in order to maintain temperature. This would cause charging to turn on and off every few minutes. Perhaps that isn't a problem. It is solved easily if the Buddy has minimum cycle time protection for just such consideration but this thing is an a Dryer Buddy, not an Oven Buddy. The other thing is that an oven usually has some kind of control system that will be drawing power continuously to, at least, operate the clock that is found on most ovens. That might prevent the thing from ever switching to charger mode.
BTW I get the impression that you may be confusing an oven of the type which plugs into an 14-50R with a toaster oven.
With the Dryer Buddy the switchover is automatic. If he is charging the car and turns on the oven charging is suspended until the oven goes off at which point charging resumes. One need remember nothing. This is much more practical. However there may be some other things to consider. An oven cycles on and off in order to maintain temperature. This would cause charging to turn on and off every few minutes. Perhaps that isn't a problem. It is solved easily if the Buddy has minimum cycle time protection for just such consideration but this thing is an a Dryer Buddy, not an Oven Buddy. The other thing is that an oven usually has some kind of control system that will be drawing power continuously to, at least, operate the clock that is found on most ovens. That might prevent the thing from ever switching to charger mode.
BTW I get the impression that you may be confusing an oven of the type which plugs into an 14-50R with a toaster oven.
Yes, there are, but I really think you are jumping to an assumption you don't need to be, and there are much simpler alternatives.
A lot of people seem really stuck on this idea that the thing they must have is a 50A outlet. Why? You just said that you are retired and don't drive that much, so maybe a 20A or 30A outlet would still be plenty for home charging. Many people use that. So the thing to do is to get a load calculation done. That tallies up the loads in your house compared to your total service to see how much of it is being used and how much spare capacity you still have available. That should show some number of amps available. If that is 23, then you would be allowed to add an extra 240V 20A circuit. However, there is another thing:
My house also has a 125A panel, and it was fine to add a 50A outlet because of this factor that does relate to your oven. Load calculations have a specific provision called "non-coincidental loads", which means loads that will generally be running at different times. So this is a perfect case of that. Your oven is a daytime load, and your car charging will be a nighttime load if you set it to start like at midnight or 1:00 AM or something. The load calculation then says that you can list these together but count the amps of only whichever is larger of the two. So if your oven is a 40A or 50A circuit, you could have a car circuit added at the same level, and it wouldn't change your load calculation at all.
I love to have the "specifics" on that. I've never been able to find anything in the code that was less than pretty vague. 220-60 applies to non residential buildings. I've observed that 400 or 450 amps of breakers on a 200 Amp panel raise no eyebrows and have been assured by at least two separate electricians that that is the case. OTOH i have a 200 amp panels, installed by a licensed electrician, that has a 100 amp circuit for the Tesla, A 100 amp sub panel (with more than 100 amps worth of breakers on it) and probably another 400 amperes worth of other breakers in the main panel. Now I am confident that I have not overloaded the panels becuase many of these loads come on seldom if ever, heat and cooling don't come on simultaneously etc but more to the point I keep historical records and the most ever pulled out of that panel has been 170 A when an electric E-heater cam on while the Tesla was charging at 72 A. That condition persisted for 7 minutes and has happened only once since the 100 A Tesla circuit was installed. Thus I have, I think, a pretty good argument for an inspector should this setup ever be questioned but if there is something hard and fast in the code that I can use to see if I am compliant I'd like to check it out.
I would only encourage OP to install the 14-50R if I had historical use data. kWhr data is not very useful but some utilities have installed "smart" meters that now calculate peak load and report that on the bill. Check to see if that number is there. It might help you to decide. I've found that the peak load on my house runs from 18 - 22 % of my service. Clearly I could install quite a few more circuits. This may or may not be the case for OP.
Watts_Up
Well-Known Member
You are right, unless you bake pies for living, cooking occurs mostly around dining time. And dryer usage is similar.
However heating and air cooling can occurs all around the day or night.
So to handle complex load calculation, some EV Energy Management Systems use real time consumption to regulate EV charging.
Well, it is 220.60, but I had not heard that the non-coincident load provision laid out there only applies to non-residential buildings.
NEC 220-60 Noncoincident Loads - Mike Holt's Forum
https://iaeimagazine.org/magazine/2012/07/16/article-220-continuation/
Satisfying Conditions
That is another method that can be used in load calculations. Instead of all of the assumptions and approximations about 50% use for this or 80% use for that, you can substitute if you have logged usage data for at least 1 year. Then, you can demonstrate the amount of spare capacity you really have. I don't know the code reference for this one, but I've seen @eprosenx comment on it a few times, so he probably knows where that one is.
This is actually what most of the examples are for. It is considered a given that you are not running both the heating and the cooling at the same time, so those are frequently paired up in a non-coincidental load calculation.
I think it is best to have an electrician give you are recommendation on the max amps to put on your 240V Tesla charging circuit. Let him or her do the load calcs.
I did, and even got a permit for the charger so everything was documented and signed off by the city. Just in case something when seriously wrong and we ended up in a finger pointing battle.
I did, and even got a permit for the charger so everything was documented and signed off by the city. Just in case something when seriously wrong and we ended up in a finger pointing battle.
eprosenx
Active Member
220.60 is super vague. But even the basic load calculations for a residence (not including 220.60) only have you count the larger of the heating or the cooling load. Generally residential hvac is not that complex and would never be running the heating and the cooling at once. Commercial is a lot more complex (and could have cooking and heating loads at the same time), but they would likely never ever be full bore heating and full bore cooling at the same time.
I think a lot of leeway is given to the AHJ in 226.60. I think a clear cut case would be something like two machines that require the same physical space to operate. It is easy to argue they would likely not be used at the same time. But say having a Wall Connector and a 14-50. You could argue that you would never use both at once, but the AHJ could challenge you saying “well what if the next owner has two EV’s and charges them at once”? I see no reason 220.60 would not apply to residences fwiw.
Anyway, 220.87 is what allows you to use a year (or 30 days!) of data to justify adding load beyond the calcs.
Watts_Up
Well-Known Member
Since you have enough Amp capacity, in general it is simpler to use a tandem circuit breaker than adding a new panel.
It seems that your electrician recommend a new panel to justify labor cost.
You should require a detail for the estimate labor and hardware cost.
Hardware might be less than 10% of the total estimate cost.
$16.83 - BR 2-50 Amp 2-Pole BQ (Independent Trip) Quad Circuit Breaker
Uses and Limitations of Tandem Circuit Breakers
How far is your main panel from where you plan to install the UMC?
How much then would be the cost of installing a 1" conduit and a NEMA 14-50 plug?
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What he actually wants is skinny dual pole breaker. One can often work one of those in to a full panel by using skinny style breakers elsewhere (including tandems). But the ability to use the skinny breakers is limited by how the stabs are arranged in the panel and they only seem to be available up to a size limit. I have a panel, for example, where the dual pole skinnys can only go in a few slots at the bottom of the panel. Even then one can often pull out two existing old style (fat) single pole breakers and replace them both with a skinny style tandem thus freeing a slot. Do that again and you have freed two fat slots - enough for a fat style dual pole if you have to use one of those.
Another possibility, rather than a new panel is a sub panel.
Another possibility, rather than a new panel is a sub panel.
Thank's. That's the chapter and verse I'm looking for.
The problem is, of course, that when doing new construction you are at the mercy of the electrician and utility. That is how I wound up with 600 A service (and a 600 A transfer switch for my 200 A generator). I had figured that I'd need 200 A service but, as one never knows what the future holds, asked them to install 400 A. They came back and said the utility said I must have 600 A (with the transfer switch) even though I told them to put the 14-50R outlets (which I thought at the time I'd be using for electric brewing) before the transfer switch. I then left for the winter (don't do that!) and when I came back in the spring there was a shiny new 600 A transfer switch, 3 ø of course because they don't make 600A 2 pole transfer switches, that is not compatible with the generator's app.
In the two years since this was done the maximum I have ever taken was 139.8 A when all three stages of E-heat came on for 5 minutes. Were I here charging the Tesla when that happened I'd be adding at most 40 amp to that. Two hundred amp service would be fine for me. Going to 400 was belt and suspenders attitude for whom I have no one to blame but myself but 600? Whom do I sue? No one, if I'm smart according to the general contractor.
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