There’s a big difference between a dryer running for an hour at most and a car charging for eight hours.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Home Charging Question on Using Electric Dryer Outlet 10-30A
- Thread starter Toysla
- Start date
Dryer heating elements also cycle on and off to maintain the desired temperature. They definitely aren't a constant load like an EV is.
Oyster Bait
Member
I am renting a workshop with precisely that outlet and am charging my Tesla there at 20 amps, getting a 15 mph charging rate. I bought this pigtail adapter
https://www.amazon.com/gp/product/B078JLDB3Z/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
from Amazon for $40, to adapt to the NEMA 14-50 adapter in the portable charging kit.
The vendor's website is Electric Vehicle Charging Adapter Cord and you can find more information there.
My workshop is remote from my apartment and I haven't charged my Tesla for more than a couple hours at a time but I was comforted that none of the adapters or wires were more than luke warm at the end of the charging session. My landlord said he had 20 amp breakers on the two legs of the circuit to the outlet and would be happy to install higher amperage breakers but we put that off until we determined what gauge wires were in the box.
https://www.amazon.com/gp/product/B078JLDB3Z/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
from Amazon for $40, to adapt to the NEMA 14-50 adapter in the portable charging kit.
The vendor's website is Electric Vehicle Charging Adapter Cord and you can find more information there.
My workshop is remote from my apartment and I haven't charged my Tesla for more than a couple hours at a time but I was comforted that none of the adapters or wires were more than luke warm at the end of the charging session. My landlord said he had 20 amp breakers on the two legs of the circuit to the outlet and would be happy to install higher amperage breakers but we put that off until we determined what gauge wires were in the box.
Last edited:
I’m in the same situation using a dryer plug to charge my Model 3. I originally wanted to install a new line but this would have needed significant work in the panel and because I’m renting the place, I did not want to pay myself for it.
So I bought an adapter
https://www.amazon.com/gp/product/B06VWGVQDF/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
And an extension
https://www.amazon.com/gp/product/B0024ECIP0/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
I set my charging rate at 24AMP and I’m getting 6kw and 230v. I’v been monitoring the temperature of the outlet, cable and breaker with an infrared thermometer and it has been fine.
Make sure to verify your electric cable in the conduit has the proper gauge for your breaker.
So I bought an adapter
https://www.amazon.com/gp/product/B06VWGVQDF/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
And an extension
https://www.amazon.com/gp/product/B0024ECIP0/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
I set my charging rate at 24AMP and I’m getting 6kw and 230v. I’v been monitoring the temperature of the outlet, cable and breaker with an infrared thermometer and it has been fine.
Make sure to verify your electric cable in the conduit has the proper gauge for your breaker.
But there is no difference in this situation. His dryer is on a 30amp breaker and installing the -30 tesla adapter he got, it would automatically limit the car to 80% of that breaker rating or 125% of the load, whichever way you want to do the math. If the breaker is a 30amp breaker then there is no difference if the guy is using the circuit for his dryer or his car.
In theory, yes, but you’re assuming the wire gauge is correct and all the connections are tight and the outlet is in good condition. We’re not assuming that, because of the apparently jury rigged setup of mismatched outlet and breaker. That’s the reason for the recommendation to have an electrician take a look and change outlet to what’s appropriate.
Teslas have circuitry to detect how many amps can be safely drawn from the outlet they are plugged into and they will adjust their charge rate to a safe level. If for example the dryer circuit in question is fused at 30A the car will only draw about 20A automatically.
Of course it would be preferable for the OP to have a higher amperage circuit to use to charge his car. But the car will charge just fine overnight at 20A.
That would of course be a very sensible thing to do.
I’m afraid someone may misinterpret this. The car can’t detect what the “fuse” (circuit breaker) is that’s protecting the circuit, or if the wiring size is correct to be safe for that draw. What the car detects is the adapter that is attached the UMC. If it’s the 14-30 adapter, for example, the car assumes it’s a 30A circuit and will set to draw 24A (80% of 30A) automatically. If that 14-30 outlet is wired to a 20A breaker though the car has no way to detect that and will still try to draw 24A.
If the car is hooked up to a 30a circuit and has the 14-50 adapter on it will try to pull the max amps as if it were a 50amp circuit. If the car is hooked to a 30 amp circuit and has the 14-30 adapter on then it will only pull 24 amps (the max for a 30amp circuit) The car has no way to know what size breaker is on the circuit. The reps tried telling me it didn't matter what size breaker was used the car would know and automatically reduce draw, there is no way to now how many amps a breaker is rated for by plugging into a socket on the circuit.
Yeah, we can add that to the list of stupid stuff Tesla people have said. We used to have a thread of this but I can’t find it.
Oyster Bait
Member
After I got everything connected the first time, the charging didn't start out so smoothly - charging started then stopped a couple times and tripped the breaker once. I lowered the charging amperage on the charging page on the screen in the car to 20 amps and everything has gone smoothly ever since. It's curious to watch - the charging rate starts out at zero, then after minute or so it shows 1 MPH, then another minute or so it goes to 2 MPH etc. etc. Eventually getting to 15 MPH.
I don't know what automatic sensing the Tesla does, but I know from experience you can manually change the charging rate and that intuitively seems like a safe way to approach the current draw issue.
Me thinks this Dryer Buddy is the best answer to my dilemma. I want to appreciate and thank all of you for your input ideas and help.
This Tesla phenomenon is truly an eye-opening and welcome experience. This quirky Elon guy is one pretty smart dude with genius ideas & follow-through, using cutting-edge technology mixed in with some theory Z management ;-). I think what's going on now is only the tip of the Elon's iceberg. Perhaps Tesla will become much more integrated into our personal and business infrastructure than we ever imagined. Time will tell if he becomes the Steve Jobs of the transportation (& energy) industry.
I have a question of using that kind of adapter on Amazon . Since the NEMA 10-50 has two hots and a NEUTRAL only,no GROUND, while the Tesla UMC needs the GROUND connection instead of NEUTRAL. Using that adapter will cause safety problem because of missing of GROUND connect to the UMC? Thanks
Xelloss99
Member
The Tesla 10-30 adapter does the same thing, connects your house Neutral to UMC Ground.
There is no inherent safety problem with doing this, because there is no touchable conductive surface anywhere on the car or UMC which is in contact with the UMC ground (and hence in this case the house Neutral, in case there is some form of Neutral wiring fault)
A third party 10-50 adapter to 14-50 adapter will do the same for a 50A circuit what the Tesla adapter does for a 30A circuit, with the only difference is that the third party adapter doesn't monitor the outlet temperature.
If it were me, I would do as others have suggested:
1. Get an electrician over to confirm the makeup of the entire circuit. Perhaps the wiring is sufficient for 50 amps. Perhaps there is already a ground wire in there. Perhaps your fuse (circuit breaker?) can be upgraded to 50 amps or more.
2. Whatever the electrician finds, have him install a new, modern outlet that matches the breaker.
3. Have him install the dryer buddy.
4. Have him swap the power cord on your dryer to match outlet #1 of the dryer buddy.
5. Get the appropriate adapter for your mobile connector to plug into outlet #2 of the dryer buddy.
1. Get an electrician over to confirm the makeup of the entire circuit. Perhaps the wiring is sufficient for 50 amps. Perhaps there is already a ground wire in there. Perhaps your fuse (circuit breaker?) can be upgraded to 50 amps or more.
2. Whatever the electrician finds, have him install a new, modern outlet that matches the breaker.
3. Have him install the dryer buddy.
4. Have him swap the power cord on your dryer to match outlet #1 of the dryer buddy.
5. Get the appropriate adapter for your mobile connector to plug into outlet #2 of the dryer buddy.
While the car can't detect what size breaker is installed, it doesn't really need to. If the car tries to draw more current than the breaker can provide, the breaker will trip. That's the whole point of a circuit breaker ;-)
The car does, however, detect voltage drop. This is why you see the current start at 0 and slowly ramp up to the set current level. If the drop is too high (due to wiring being too small gauge for example, or the run being too long, or a bad connection somewhere), the car will drop the charging current automatically to a rate with minimal (less than 5% I think?) voltage drop and stay there. It will also pop a warning on your screen saying to check your wiring and make sure you're not using extension cords.
"the breaker should, hopefully, trip"
There--fixed that for you. There were a couple of brands of panels/breakers, like Federal Pacific, that were notorious for having awful failure rates, like about one third of the time, they would fail to trip from an overcurrent and would stay locked on, leading to fires. They were outlawed many years ago, but some old houses still have them. But even for breakers that work well, hitting their trip mechanisms is a little hard on them, so you don't want to have that happen often.
So it's just a bad idea to set something up which needs someone to remember to change a setting and could rely on tripping a breaker often. So do it right. Get one of the proper adapters that automatically sets the current for you, without having to remember to change the setting in the car.
davewill
Active Member
There have been many folks that have had the car's setting revert to full rate on it's own. Relying on the setting in the car is fine for occasional use where you can manually verify the setting is correct when plugging in, but trusting the car to remember on it's own day in and day out is just not a sound idea. Even if you tell yourself you'll check it every time, after it's gotten it right every day for couple of months, you're bound to become complacent about it.
Exactly. The only way it's automatic is if the right adapter is used on a UMC, or the switches are set correctly on a wall connector or other EVSE. Otherwise there is nothing in the car that would prevent trying to draw more than the breaker size. Every now and then we get someone posting who thinks the bad circuit detection code is some sort of automatic circuit size detection system, but it's REALLY not.
Last edited:
Thank you for the info. I did same thing. I made an adapter (actually, a extension cord) to plug into 10-30 dryer receptacle. The other end of the extension cord is a 14-50 and use UMC GEN 2 to charge my Model 3. The Neutral of the 10-30 is wired to Ground of the 14-50 and the Neutral of the 14-50 left unconnected (since UMC does not use Neutral). It's works fine so far (I limit the charge current to 25A). For safety, I'm thinking of connecting the Neutral and Ground together at the Service Panel. Is it doable? Thank you.
Yes, that would be the correct way to switch those wires, since the Tesla charging system does try to check for the ground, and it will treat the neutral pin of a 10-XX series outlet as if it is the ground.
As someone pointed out to you in another thread, that is supposed to be 24A or less.
Here's a thing I and some other people have done to help address this particular issue. Back when Tesla did not have many adapters available, we did get some of these kinds of adapters that switched a lot of things to 14-50 outlets. That would normally require this manually dialing the amps down on the car's screen, which is not super reliable long term. So when I was finally able to get a Tesla 14-30 plug, I cut the neutral blade off of the plug with a hacksaw. Now, it can plug right in to my adapters and extension cords that have 14-50 outlets, but it will properly limit the current to 24A for plugs like a TT-30 or 10-30.
Similar threads
- Question
