Some questions about 14-50 receptacles

[Villainthrpist]

I'm looking to get a NEMA 14-50 receptacle installed and had a few questions, if anyone can help out. I'm looking to disconnect a wall heater right next to my garage and use that line to power the receptacle. It is powered by a 240V 20A breaker. The heater is the only thing that is on this circuit. I understand 20A is low for charging but it is better than 120v.

1. The Mobile Connector accepts a maximum current of 32A. Does this mean that it can accept lower amperages?
2. I don't know what the gauge is of the wire that is currently being run from the breaker to the wall heater. Is there a chance that the wire is not to spec for the receptacle?
3. The Hubble 14-50 receptacle I am looking at says it's rated for 50A. Do I need a breaker that is also rated for 50A or is it fine that the breaker output is less than the receptacle?

I ordered a wall connector to install in the garage but I am in a rental and the electrician quoted me $1k to disconnect the wall heater and run about 25ft of wire through wire track into the garage and connect the WC. I'm only going to be in this place for another year & 1/2 so the cost didn't seem to make sense, only to have to pay to get it disconnected when I leave and the set up again at my next residence.

 

[ATPMSD]

You cannot pull more than 20A through your existing wire and in fact the most you can use on that connection is 16A (there is an 80% rule for continuous load items) so you need a new wire. It is extremely unlikely the wire is rated for the kind of loads EV charging requires.

$1,000 may be a reasonable price based on location of the breaker box.

So then as to hardware cost, in addition to the wire and running it:

The Wall Connector is about $400 and the breaker is about $15. If you install a 50A circuit you will charge at 40A and if you install a 60A circuit you will charge at 48A. It is very easy to remove the wall connector and take it with you (easy DIY). Your sunk case is just $15 for the breaker,

The mobile connector is $230, the Hubbell NEMA 14-50 outlet is about $80, you will need a GFCI breaker at about $150, and some sort of cable management system for say $35, this total $492. You will be limited to a 32A charge rate (mobile connector limit.) It is of course easy to take the mobile connector with you, but the outlet and breaker costs are a sunk costs.

If you do not do one of the above, what other option(s) are you considering?

 

[Sophias_dad]

It would be odd for the wire that was installed to be able to be rated more than 20A, but its not impossible. 20A/240V charging should be plenty depending on how far you drive. Many people can get by with standard 120V charging(either 15 or 20A, which is really 12/16A). I don't have the chart handy, but a model Y would get about 3800/270 = 14 miles per hour of charging on a 20A/240V circuit., or about half that on a 5-20 which you might already have in the garage for FREE. Even the most common 5-15 outlet will give you 5 mi/hr. Do you really drive more than 60 miles a day?

The UMC will happily accept 20A, just get a 6-20 outlet installed, which would eliminate the need for more wiring.

Have you talked to your landlord about any of this? As a landlord, I'd be pretty annoyed if my renter went screwing with my house like this. It may well be a violation of your lease. Who knows, maybe the landlord would be all-in for EV's and get a subpanel installed in the garage which would power both the heater and the EV, and even pay for the outlet installation.

I assume you know the HPWC can be dialed back to 20A, and that might save you almost all your changes. I don't know what the layout of your space is, whether the 25 feet of new wire you referred to is just for the 14-50, or if you are putting the plug somewhere other than where the heater was.

 

[GSP]

@Villainthrpist -

The least expensive option would be to install a 6-20 outlet, using the existing 20 A breaker and wiring, and buy Tesla’s 6-20 UMC adapter. This adapter will automatically limit charging to 16 A, the maximum allowed on a 20 A circuit. Only 16 A is not ideal, but it should work fine as long as your daily driving is not extremely long.

If you have already received your wall connector, it can be configured for a 20 A circuit, also allowing 16 A maximum for charging.

I have been charging my Teslas at only 16 A at my home for 6 years, and my cars are almost always fully charged by morning [I set to 80%]. In the rare case that I arrive home late at night with low SOC, my car still has plenty of charge for the next day’s driving, and catches up to fully charged the next morning.

With this option, you can save your money to install a wall connector when you move to a more permanent location. Installation on a 40 A circuit should be plenty for 99.9% of drivers. To get the maximum possible charge rate the wall connector will need a 60 A circuit.

GSP

 

[Villainthrpist]

You cannot pull more than 20A through your existing wire and in fact the most you can use on that connection is 16A (there is an 80% rule for continuous load items) so you need a new wire. It is extremely unlikely the wire is rated for the kind of loads EV charging requires.

$1,000 may be a reasonable price based on location of the breaker box.

So then as to hardware cost, in addition to the wire and running it:

The Wall Connector is about $400 and the breaker is about $15. If you install a 50A circuit you will charge at 40A and if you install a 60A circuit you will charge at 48A. It is very easy to remove the wall connector and take it with you (easy DIY). Your sunk case is just $15 for the breaker,

The mobile connector is $230, the Hubbell NEMA 14-50 outlet is about $80, you will need a GFCI breaker at about $150, and some sort of cable management system for say $35, this total $492. You will be limited to a 32A charge rate (mobile connector limit.) It is of course easy to take the mobile connector with you, but the outlet and breaker costs are a sunk costs.

If you do not do one of the above, what other option(s) are you considering?

Thanks for the thorough reply.

To be clear, the $1000 is to run additional wire from the lines connected to the wall heater into the garage, not from the breaker box. The original plan was to connect that wire to the Wall Connector. Running new wire from the panel is not an option.

I was worried about the wire…So since the wire is already used on a 20A circuit, there is a chance that it is still not even good enough for EV charging loads?

I knew there there would be a reduction in amperage for continuous load items and I am ok with what I would potentially get. Just trying to do something better than a 120V.

I already have the Wall Connector and the Mobile Connector is on it’s way.

At this point if I could use the wire from the wall heater to connect to a NEMA 14-50, it would be cheaper to get the receptacle and breaker installed right where the wire exists rather than run additional wire to the garage to install the Wall Connector.

Obviously, if the wire is no good then all of this is a non starter. I just assumed that the wire should be fine since essentially the Mobile Charger was made to plug into a regular wall outlet. I get that this changes as the amps and volts change.

If I can’t get the Wall Connector or NEMA receptacle install then I would have to try resorting to the 120V or super charging until I relocate.

 

[minnesnowta]

As others have mentioned, get a 6-20 outlet installed and purchase the 6-20 adapter from Tesla. The UMC will automatically limit itself to 16 amps (20 * .8) so you don’t have to bother changing the amps.

 

[Villainthrpist]

It would be odd for the wire that was installed to be able to be rated more than 20A, but its not impossible. 20A/240V charging should be plenty depending on how far you drive. Many people can get by with standard 120V charging(either 15 or 20A, which is really 12/16A). I don't have the chart handy, but a model Y would get about 3800/270 = 14 miles per hour of charging on a 20A/240V circuit., or about half that on a 5-20 which you might already have in the garage for FREE. Even the most common 5-15 outlet will give you 5 mi/hr. Do you really drive more than 60 miles a day?

The UMC will happily accept 20A, just get a 6-20 outlet installed, which would eliminate the need for more wiring.

Have you talked to your landlord about any of this? As a landlord, I'd be pretty annoyed if my renter went screwing with my house like this. It may well be a violation of your lease. Who knows, maybe the landlord would be all-in for EV's and get a subpanel installed in the garage which would power both the heater and the EV, and even pay for the outlet installation.

I assume you know the HPWC can be dialed back to 20A, and that might save you almost all your changes. I don't know what the layout of your space is, whether the 25 feet of new wire you referred to is just for the 14-50, or if you are putting the plug somewhere other than where the heater was.

Just wanted to give a quick thanks for all the replies at 6:30AM haha.

But you nailed it on the head. I assumed the wire would have be good for at least 20A given that's what the breaker is rated for. 20A(16A) is perfect for my needs. My girlfriend and I will be sharing the car and it would see approx. 60 miles a day and my math came to about 13-15 mi/hr as well.

I was under the impression that the 5-20 only gave about 3 mi/hour? If I leave it on an 8 hour charge, those 16 extra miles could make a difference.

In regard to the landlord, I live in a corporate complex and I spoke with the front office about this. There are a number of other residents here that have had EV work done and they even gave me the number for their in house electrician that did the work for them. That's who gave me the quote. I would be responsible for all costs however.

The plan was to hook up the HPWC and dial it back to 20A. That seemed like the right move as it would be how I could get the most charge out of the available breakers without having to install a receptacle or GFCI breaker.

I attached some pictures of my layout. The idea was that either the receptacle or the HPWC would need to be located in the garage which would require routing additional wire from pre-existing 20A line from the wall heater.

Wall Heater - Door to the right leads to the garage

Shot from the garage

I don't know why I didn't make this connection sooner but the idea was to install the 14-50 outlet right next to the heater. I didn't even think about putting the HPWC there. I just took some measurements and I SHOULD have enough cable to reach the car (Yes the door would need to stay open).

I'm really hoping this can be the solution. I will unbox the HPWC and see if the cable reaches.

 

[Villainthrpist]

@Villainthrpist -

The least expensive option would be to install a 6-20 outlet, using the existing 20 A breaker and wiring, and buy Tesla’s 6-20 UMC adapter. This adapter will automatically limit charging to 16 A, the maximum allowed on a 20 A circuit. Only 16 A is not ideal, but it should work fine as long as your daily driving is not extremely long.

If you have already received your wall connector, it can be configured for a 20 A circuit, also allowing 16 A maximum for charging.

I have been charging my Teslas at only 16 A at my home for 6 years, and my cars are almost always fully charged by morning [I set to 80%]. In the rare case that I arrive home late at night with low SOC, my car still has plenty of charge for the next day’s driving, and catches up to fully charged the next morning.

With this option, you can save your money to install a wall connector when you move to a more permanent location. Installation on a 40 A circuit should be plenty for 99.9% of drivers. To get the maximum possible charge rate the wall connector will need a 60 A circuit.

GSP

As others have mentioned, get a 6-20 outlet installed and purchase the 6-20 adapter from Tesla. The UMC will automatically limit itself to 16 amps (20 * .8) so you don’t have to bother changing the amps.

I'll look into the 6-20 as an option. Thanks for the feedback!

 

[ATPMSD]

At this point if I could use the wire from the wall heater to connect to a NEMA 14-50,

Do not install a NEMA 14-50 outlet on a 20A circuit! Install a 6-20.

 

[Villainthrpist]

Do not install a NEMA 14-50 outlet on a 20A circuit! Install a 6-20.

Noted. Thanks.

The HPWC should be fine on the 20A, right? As long as I configure it to run at that?

 

[ATPMSD]

Noted. Thanks.

The HPWC should be fine on the 20A, right? As long as I configure it to run at that?

Yes sir!

 

[ATPMSD]

SHOULD have enough cable to reach the car (Yes the door would need to stay open).

The wall connector’s cable is 24-feet and the mobile connector is 20-feet. Remember to consider the distance from the connector to the floor, out the door to the car, then up from the floor to the car. You should seriously consider extending the wire inside the wall, from inside into the garage itself.

 

[Villainthrpist]

The wall connector’s cable is 24-feet and the mobile connector is 20-feet. Remember to consider the distance from the connector to the floor, out the door to the car, then up from the floor to the car. You should seriously consider extending the wire inside the wall, from inside into the garage itself.

Unfortunately extending the wire into the garage just does not seem worth the extra $500.

The electrician quoted me $450 to set up the charger right where the wall heater is. $1k to extend the wire into the garage.

I’m going to test out the length later. Will need my girlfriends help. Some rough measuring gives me about 6ft of wiggle.

 

[Sophias_dad]

A 5-20 will give around 1920w, divided by 270 gives you a bit more than 7 miles an hour. That's easily 70 miles a night. I'd buy the 5-20 adapter for the UMC for $35 and be happy. You also have weekends for even more charge time.

 

[jcanoe]

What about using the 120V receptacle(s) in the garage to charge with the Tesla Mobile Connector?

A 5-15 receptacle (the standard 15 amp, 120V receptacle) will enable you to charge using the Mobile Connector with the included 5-15 power plug adapter, capable of adding 3 to 4 miles to the range of the Tesla Model Y per hour.

A 5-20 (120V and a 20 amp circuit) will enable you to charge using the Mobile Connector with the optional 5-20 power plug adapter, capable of adding up to 7 miles added to the range of the Tesla Model Y per hour.

I would use the Tesla Supercharger network as required. You can also use PlugShare app to locate DC Fast Charge stations in your area. The Tesla CCS1 adapter costs ($250). Using the CCS adapter you would be able to use Electrify America, Chargepoint, EVgo, and Blink DC Fast Charge stations. The DC Fast Charge stations may cost less than using the Tesla Supercharger network.

I would not spend any significant money to upgrade the electrical at the rental. Save the Wall Connector for when you have your own place.

 

[D.E.]

It looks as if you are new at this so I’ll tell you what I know. I invite anyone else to jump in. I am not an electrician.

The car can charge from a 120V outlet. I get 3-4 miles per hour with my S charging this way. You cannot charge at the same amperage as the breaker. You can for a short while then the breaker will probably trip. A breaker has one function, that is to protect the wiring in the house. Modern breakers often trip slowly, they’ll often deal with a larger amperage but not for very long. Just because a breaker doesn’t immediately trip doesn’t mean it won’t trip later. If your breaker trips, you can set the car for a lower maximum charge rate.

The car will have a certain amount of “overhead” when charging so it is more efficient to charge at a higher amperage. I think of that overhead as fixed but that might not be right. In any case the increase in amperage will result in more miles of charge than one might think by simply doubling the 120V charge rate.

You can use various adapters and you can get a 50A extension cord. The cord is very heavy, it’s similar to a garden hose in diameter. Mine I think is 30 feet. Then one can add various adapters to the end. I have an adapter that goes to a modern clothes dryer outlet. With the extension and the adapter I can charge from a 240V household dryer outlet. I believe I get 15 or so miles of charge per hour that way, but it’s been a while.

If the time you anticipate spending in the current rental is limited, I’d look into using the available electrical supply/outlets. If there’s a clothes dryer that’s an option. An extension cord/adapter system will travel with you. We’re talking fat 50A extension cords, not the 120V cords you find at local retailers. Those mass market cords may provide a solution as well but you must pay attention to the ratings, the quality, the size of the wire and length of the cord. If any cord ever gets warm, that’s a serious warning. I have a small welder, 15A of current is sufficient to weld steel. Not as it comes from the wall but the point is that 15A is quite a bit of power. There’s another consideration, most things plugged into a 120V outlet sip power and don’t draw anything like the amount your car will. The car is a sustained high draw device.

There are a large number of outlet configurations in 120V and 240V, especially in older buildings. You can find about any adapter you need. The car is very good about using whatever you supply it. It’s good at limiting the amperage though a setting on the screen but that setting can change after a software update so always check. If you trip a breaker after a software update, that’s something to check.

On a positive note, it’s better for the battery to charge relatively slowly. The superchargers charge quickly but that’s harder on the battery than a slow trickle. You can find charts of various adapters on line. That chart will supply you with the information you’ll need if you go the adapter/extension cord route. I can charge about anywhere, from a 120V15A outlet up to 240V50A.

If using a nondedicated circuit, you want to be aware of other things on the circuit. A compressor motor in a refrigerator or freezer can draw a lot of current as it starts, much more than when simply running.

I can’t think of anything else to tell you right now, but this is far from exhaustive. It should get you started, though. You have a lot of options but you must read and know exactly what you are doing.

There are some tiresome people that go through blindly disagreeing with posts for no apparent reason. If anyone disagrees with something I‘ve posted here, please post exactly what it is that causes you to object, and why.

 

[ATPMSD]

What about using the 120V receptacle(s) in the garage to charge with the Tesla Mobile Connector?

Great idea! IF the 120V outlet in the garage is 100% dedicated it is easy to convert it to a 240V circuit. All you need is a 6-20 outlet (or the wall connector) and to change the existing single pole 20A breaker to a dual-pole 20A breaker, assuming space exists in the breaker box of course.

 

[jcanoe]

Great idea! IF the 120V outlet in the garage is 100% dedicated it is easy to convert it to a 240V circuit. All you need is a 6-20 outlet (or the wall connector) and to change the existing single pole 20A breaker to a dual-pole 20A breaker, assuming space exists in the breaker box of course.

I don't see the benefit of improving someone else's property (without permission from the owner and possibly the owner paying half of the cost.)

 

[exxxviii]

IF the 120V outlet in the garage is 100% dedicated it is easy to convert it to a 240V circuit. All you need is a 6-20 outlet (or the wall connector) and to change the existing single pole 20A breaker to a dual-pole 20A breaker

Is that to electrical code anywhere? To do that, you would have to convert the white neutral wire to a hot wire and use the unshielded ground wire as neutral. It would work electrically, but I wouldn’t confess to anyone that I did that.

 

[mspohr]

Noted. Thanks.

The HPWC should be fine on the 20A, right? As long as I configure it to run at that?

80% rule. Run the HPWC at 16 amps.