Your electrician gave you good advice. If you use the 14-50 receptacle and the Mobile Connector with the 14-50 power plug adapter you should plan to leave the 14-50 power cord plugged into the receptacle. You don't want to be frequently plugging and unplugging the power plug from the 14-50 receptacle as most 14-50 receptacles are not designed for a high volume of plug and unplug actions.. You should not let the Mobile Connector hang supported by just the power plug adapter pigtail as over time the plug will fail. Tesla sells a charging cable organizer that includes a wall mount holster for the Mobile Connector electronics package or you can find similar brackets on Amazon or Etsy or figure another way to support the Mobile Connector.
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Wall connector vs. NEMA 14-50 connector
- Thread starter Tobin
- Start date
I am waiting for delivery of my MY and have a quick question about home charging. My house was built 4 years ago and it has a NEMA 14-50 receptacle in the garage. I cannot find information about the maximum current for this outlet. Is it safe to charge a MY with this outlet and a NEMA 14-50 adapter? Is it a code violation if you put a NEMA 14-50 receptacle and it is wired to support only 20A draw?
Welllll...I would have said yes, it's that basic and simple except for your follow-up question. The Model Y will not come with the 14-50 adapter plug included, so you would want to order that from Tesla. It's $35. So if it were a standard normally installed 14-50 on a 50A circuit, that's what you would do. But...
Oh, uh, what? Are you saying you've looked, and it is actually hooked up to 20A two pole breaker? Technically that is not a code violation, but it's usually sloppy bad practice. Code specifies that the breaker must not be higher than the rating of the outlet. So for a 14-50, you are not allowed to use for example a 60A breaker. But someone could put a 20 or 30A breaker on there. There are very few reasons for doing that though.
How are you interpreting this? I've seen several people confused about how the breaker ratings work, where they think you multiply or divide by 2 because of voltage levels between 120V or 240V or one and two pole. What does it look like and what is the actual number printed on it? I'm wondering if it says 40, but you're thinking it like divided in half for some reason, which is not correct.
So here is what would happen if that's what you have. You would plug in the Tesla charging cable with the 14-50 plug, and it will try to pull the max amps that it is built for, which is 32A. And the 20A breaker should trip within a minute or two. So that's just not a good setup. So what can you do about it? Well, that depends on what size of wire you have.
1. If there is thick enough wire in the wall that would support a 40 or 50A circuit, then you could keep the 14-50 outlet and put the right size breaker on it.
2. If the wire is small, like really sized for a 20A circuit, then it shouldn't have that 14-50 outlet on there. Put an appropriate 20A outlet type on there, like a 6-20, and buy the 6-20 adapter plug from Tesla.
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The NEMA 14-50 should be installed on either a 40A or 50A double pole circuit breaker. If you look inside the cover of your electrical panel I would be surprised if the 40A or 50A breaker was not labeled Car Charger or similar. The circuit wiring should be rated for 50A even if the breaker installed is only 40A. I doubt it is other than 40A or 50A as this would be confusing to anyone attempting to use the circuit with equipment of greater than 30A. The Tesla Mobile Connector that comes with the vehicle is limited to a maximum of 32A, Tesla sells a 14-50 plug adapter on the Tesla store site (cost $35 US.) If you want to charge at 40A, the maximum when charging an EV on a 50A circuit you could use the Corded Mobile Connector (rated for use at 40A) or another EVSE.
Thanks Rocky for your quick response and advices. I have already ordered the 14-50 adapter and I will try when my MY arrives. As for the 20A number, the hand-written label on a double-lever-breaker in my electric panel reads "20 dedicated garage" so that is a wild guess but it could be something else. I will take a close look at my panel. Thanks!
I use the 14-50 and I'm quite satisfied. I can go from pretty much empty to full overnight. My opinion is that unless you're maxing your range almost every day, there's not a good reason to worry about higher than 32A. Except on trips of course but there you'll be wanting supercharging. I think there are some destination chargers where the corded connector might help but I think that's pretty rare.
Some think the wall connector is a better choice citing the ability to put together 2 and they can smart load balance. But of course that's only a reason if you have more than one Tesla. Others cite scheduled charging. Maybe but others complain about how Tesla does that. I do scheduled charging by changing the charge limit on a schedule via TeslaFi.
So my opinion is that the $35 for the adapter is a better choice than $500 for the wall charger or $520 for the corded mobile. Some have bought a second mobile for $275 so they don't have to unplug for a trip.
Some think the wall connector is a better choice citing the ability to put together 2 and they can smart load balance. But of course that's only a reason if you have more than one Tesla. Others cite scheduled charging. Maybe but others complain about how Tesla does that. I do scheduled charging by changing the charge limit on a schedule via TeslaFi.
So my opinion is that the $35 for the adapter is a better choice than $500 for the wall charger or $520 for the corded mobile. Some have bought a second mobile for $275 so they don't have to unplug for a trip.
Are you certain that the receptacle in the garage is a NEMA 14-50? https://www.tesla.com/sites/default/files/pdfs/installation-guides/nema-14-50-installation-guide.pdf
If on a circuit with a 20A double pole breaker it could be that the electrician installed a NEMA 6-20, a 240V/20A receptacle.
Uh, but I said don't until you can figure out what you actually have installed.
There is a hand written note actually on the breaker? The breaker handle should have a number printed or molded into it to show what it is. You should find out what's going on here, and maybe that's taking an hour of an electrician's time.
Here is a picture of my panel, and this breaker I think it is for the NEMA 14-50 outlet.
Thanks! So the wiring can support 80A on that circuit which is more than enough for EV charging.
no, it's 240/40A
But the standards are to max at 80% of the capacity for continuous draw. So that drops it to 32 which is the max for the connector that comes with your car.
You can't add 40+40 to get 80 amps. The simple explanation is that it is 40 and you're adding 120+120 to get 240V.
But the standards are to max at 80% of the capacity for continuous draw. So that drops it to 32 which is the max for the connector that comes with your car.
You can't add 40+40 to get 80 amps. The simple explanation is that it is 40 and you're adding 120+120 to get 240V.
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A real world example is our original 30 year old oven which was a 240v 40amp breaker. However we replaced it with a modern high efficiency AEG oven which required no more than a 20 amp service. So the breaker was changed from 40 amp to 20 amp to ensure it met the expectations of the downstream dedicated equipment.
No, and that's why I said this.Thanks! So the wiring can support 80A on that circuit which is more than enough for EV charging.
A lot of people think it's half or double on the amps, but it doesn't work that way. @spokey explained that well, that the double handle is connecting to both voltage parts in your panel to get the 240V instead of 120V, but the amps are still just the amps as they are printed on the handle of the breaker.
And seeing the breaker now, that is the situation I mentioned above, where a 14-50 is fairly common to put on a 40A circuit, and with Tesla's charging cables only pull 32A maximum, that's fine to just plug into what you have as it is.
Perhaps a better way of describing a double pole breaker is that the current goes "out" on one side and "in" on the other. With a 240V device, both sides are redundantly sensing the same current. Either side can trip and open both sides at once. So it's still limited to 40 amps, no halving or doubling.
I use the 14-50 Plug in the garage as we are not sure if we will move in the near future. I will say that I do take the MCU with me when we go on our trips with our travel trailer. This is because every night at the RV camp ground we plug the trailer into the 30 Amp service and the MY in to the 50 Amp service. So we get a full charge for the next days adventures.
I'm happy with the 14-50 as well. Don't take a lot of trips but have done the same. Unplug the MC and toss it (with the 14-50 plug attached) in to the frunk. If my trips increase to the point where that is a hassle, I'd buy a second connector. Maybe another 14-50 adapter although I haven't stayed in an RV park since my bicycle touring days.
However; one thing I think I've learned is that the 14-50 / wall connector debate will be here forever with passionate die-hards on both sides.
I can only think of two more passionate conflicts.
1 - Orange man our savior vs orange man the devil incarnate
2 - And of course the top worst polarization in the world: set the battery SOC to percent or miles.
However; one thing I think I've learned is that the 14-50 / wall connector debate will be here forever with passionate die-hards on both sides.
I can only think of two more passionate conflicts.
1 - Orange man our savior vs orange man the devil incarnate
2 - And of course the top worst polarization in the world: set the battery SOC to percent or miles.
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