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40amp 14-50 outlet vs Wall Connector Gen 3

kithytom

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Jul 30, 2021
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Hi electrician friends, luckily my new house has a 40 amp breaker + 14-50 outlet pre-installed in the garage.
I'm debating whether to go with outlet + mobile connector or a Gen 3 Wall Connector. Specifically for MY Long Range, will there be a difference in max output?

Side question as a noob: can I change the circuit breaker to 50 A or 60 A without any other additional works so having Wall Connector is justified?

Thanks
 
The 14-50 outlet is a 50A outlet. If it was installed to code, it will be on a 50A circuit. That it has a 40A breaker is... pretty weird, and implies that this might not be to code. In which case, get an electrician out and have them look at what you have.

But if you've got the correct wire installed for that outlet: yes, you can put a 50A breaker on it. In almost all areas (again, ask a local electrician), the same wire gauge will also support a 60A dedicated circuit for the wall charger.
 

jcanoe

Well-Known Member
Oct 2, 2020
6,763
7,668
Maryland
Hi electrician friends, luckily my new house has a 40 amp breaker + 14-50 outlet pre-installed in the garage.
I'm debating whether to go with outlet + mobile connector or a Gen 3 Wall Connector. Specifically for MY Long Range, will there be a difference in max output?

Side question as a noob: can I change the circuit breaker to 50 A or 60 A without any other additional works so having Wall Connector is justified?

Thanks
In this case the 40A breaker limits to charging at 32A whether using the Mobile Connector or the Wall Connector.

Have an electrician perform a load calculation on your existing service and panel. The electrician should inspect the current wiring to see if it is in good condition, of proper gauge for 50A or 60A service. I would start out using the Tesla Gen2 Mobile Connector with the optional NEMA 14-50 power plug adapter and see if these meets your daily charging needs.
 
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jcanoe

Well-Known Member
Oct 2, 2020
6,763
7,668
Maryland
The 14-50 outlet is a 50A outlet. If it was installed to code, it will be on a 50A circuit. That it has a 40A breaker is... pretty weird, and implies that this might not be to code. In which case, get an electrician out and have them look at what you have.

But if you've got the correct wire installed for that outlet: yes, you can put a 50A breaker on it. In almost all areas (again, ask a local electrician), the same wire gauge will also support a 60A dedicated circuit for the wall charger.
Two things:

The NEMA 14-50 receptacle can be installed on a 40A circuit when there is insufficient capacity for a 50A circuit. (The reason is there is no specific NEMA receptacle made for use on a 240V/40A circuit.) The receptacle should be labeled 240V/40A to avoid any confusion.

The wire required for a 60A circuit may need to larger gauge wire than for a 50A circuit. If the wire type is NM-B (Romex) then 6 gauge wire would support a 50A circuit but for a 60A circuit 4 gauge NM-B would be required. If the wire is not NM-B, i.e THHN type wire then 6 gauge wire would support either a 50A or 60A circuit. NM-B, typically installed in homes in walls, attics is the most common type of home wire. 6 gauge NM-B is only rated for a maximum of 55A.
 
Hi electrician friends, luckily my new house has a 40 amp breaker + 14-50 outlet pre-installed in the garage.
I'm debating whether to go with outlet + mobile connector or a Gen 3 Wall Connector. Specifically for MY Long Range, will there be a difference in max output?

Side question as a noob: can I change the circuit breaker to 50 A or 60 A without any other additional works so having Wall Connector is justified?

Thanks
You need to check your wire gauge (size). 6 gauge can handle a 14-50 outlet. If it is not 6 gauge then you need to decrease the amperage the car will pull when recharging. Check the NEMA codes for the wire sizes you need for a given amperage.
 
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Rocky_H

Well-Known Member
Feb 19, 2015
8,789
11,469
Boise, ID
luckily my new house has a 40 amp breaker + 14-50 outlet pre-installed in the garage.
Ah, yep, a lot of states are going with building codes these last few years to require some kind of circuit or outlet pre-built in for EV charging. That's a good idea, since putting the wire in while the house is being built is so much easier and cheaper than later retrofitting.
I'm debating whether to go with outlet + mobile connector or a Gen 3 Wall Connector. Specifically for MY Long Range, will there be a difference in max output?
It's totally fine to just go with the mobile charging cable that comes with the car as a permanent at-home thing. I've been using mine for over 7 years that way--just hangs on a hook on the garage wall. As to a charging difference? That's all about how many amps get passed through, but either piece of equipment will give the same charging speed if they've got the same number of amps going. The questions are just in where the limits are.

You've got a 40A circuit there. By code, that can pass 32A. That's all the mobile cable can do. You could put a wall connector on that circuit instead, but it will still only be allowed to be configured to pass that same 32A. The wall connector could do more, if you could have the circuit be bigger, with thick enough wire and bigger breaker. Don't know what you've got for wire size and type.
 

kithytom

Special Guest
Jul 30, 2021
244
136
F3V4+837
In this case the 40A breaker limits to charging at 32A whether using the Mobile Connector or the Wall Connector.

Have an electrician perform a load calculation on your existing service and panel. The electrician should inspect the current wiring to see if it is in good condition, of proper gauge for 50A or 60A service. I would start out using the Tesla Gen2 Mobile Connector with the optional NEMA 14-50 power plug adapter and see if these meets your daily charging needs.

Right on the spot! 14-50 receptacle doesn't automatically equal to 50 A circuit breaker.

I was able to find the load calculation from the builder, it seems there are still some extra left?
For the gauge I have to inspect by my own later. I'm wondering can the gauge wire for 40 A breaker carry 50A beaker as well? My hope is to not change the wire just the breaker to 50 A.

rating.png
 

Rocky_H

Well-Known Member
Feb 19, 2015
8,789
11,469
Boise, ID
I'm wondering can the gauge wire for 40 A breaker carry 50A beaker as well? My hope is to not change the wire just the breaker to 50 A.
We can't answer that unless we know what type of wire your installation is using. It's usually one of two types: either the multi-wire cable, which is called Romex or NM-B, or it is run with conduit with individual wires pulled through it. So if people just say a wire thickness, that is not quite enough information. The same wire gauge with Romex has a lower current rating than separate wires in conduit.

Here's a table that shows this:

The first column is NM-B (Romex), and the second column is for the wires in conduit. So let's look at a hypothetical for your question. See how in the 8 gauge row, if it's Romex, it's only rated to 40A? If that's what you have, then no, it couldn't be used for a 50A circuit. But if it were 8 gauge wire in conduit, then yes, that's rated up to 50A. And the 6 gauge row is rated either 55 or 65 amps, depending on which type.
 
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rjpjnk

Active Member
Mar 12, 2021
1,386
984
NJ
Interesting. So it looks like they estimated the charger to contribute 46 amps to the load.
Hopefully one of the experts here can explain how one comes up with the 9600 VA assessment for the charger when performing a load calculation like this.
 

kithytom

Special Guest
Jul 30, 2021
244
136
F3V4+837
We can't answer that unless we know what type of wire your installation is using. It's usually one of two types: either the multi-wire cable, which is called Romex or NM-B, or it is run with conduit with individual wires pulled through it. So if people just say a wire thickness, that is not quite enough information. The same wire gauge with Romex has a lower current rating than separate wires in conduit.

Here's a table that shows this:

The first column is NM-B (Romex), and the second column is for the wires in conduit. So let's look at a hypothetical for your question. See how in the 8 gauge row, if it's Romex, it's only rated to 40A? If that's what you have, then no, it couldn't be used for a 50A circuit. But if it were 8 gauge wire in conduit, then yes, that's rated up to 50A. And the 6 gauge row is rated either 55 or 65 amps, depending on which type.
This chart is gold, it will help me a lot once I find out what wires are used. Thanks!
 
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208v service, maybe a condo? The bottom line is that at 32A a 20%-80% charge will take you about 10 hours, at 48A (max possible) it would be 6-7 hours.

Unless that difference is important to you I would just keep your existing 40A receptacle and charge with the included mobile connector. Total cost about $50 for the adapter.
 

kithytom

Special Guest
Jul 30, 2021
244
136
F3V4+837
We can't answer that unless we know what type of wire your installation is using. It's usually one of two types: either the multi-wire cable, which is called Romex or NM-B, or it is run with conduit with individual wires pulled through it. So if people just say a wire thickness, that is not quite enough information. The same wire gauge with Romex has a lower current rating than separate wires in conduit.

Here's a table that shows this:

The first column is NM-B (Romex), and the second column is for the wires in conduit. So let's look at a hypothetical for your question. See how in the 8 gauge row, if it's Romex, it's only rated to 40A? If that's what you have, then no, it couldn't be used for a 50A circuit. But if it were 8 gauge wire in conduit, then yes, that's rated up to 50A. And the 6 gauge row is rated either 55 or 65 amps, depending on which type.
Turns out the wire is Aluminum 6 AWG XHHW-2, Amp rating is 55 according to the chart.
Since simply changing to a 60 A breaker is not feasible I probably will stay with Nema 14-50 with 40 A breaker then. Thanks!
 

jcanoe

Well-Known Member
Oct 2, 2020
6,763
7,668
Maryland
Turns out the wire is Aluminum 6 AWG XHHW-2, Amp rating is 55 according to the chart.
Since simply changing to a 60 A breaker is not feasible I probably will stay with Nema 14-50 with 40 A breaker then. Thanks!
There may be an issue with the Aluminum wiring. Aluminum wiring should not be used to wire receptacles. Aluminum wire is commonly used for service wiring, running wire to a sub panel. Due to the special wire termination requirements Aluminum wiring should not be used for wiriing receptacles. You need an electrician to determine what should be done.
 
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kithytom

Special Guest
Jul 30, 2021
244
136
F3V4+837
208v service, maybe a condo? The bottom line is that at 32A a 20%-80% charge will take you about 10 hours, at 48A (max possible) it would be 6-7 hours.

Unless that difference is important to you I would just keep your existing 40A receptacle and charge with the included mobile connector. Total cost about $50 for the adapter.
Thanks for sharing the real case scenarios. For my case 3-4 hours faster is a huge benefit but running new surface-mounted conduit for the 60 A breaker would cost me $600+ in my area. I probably will stay with Nema 14-50 with 40 A breaker then. Thanks!
 

kithytom

Special Guest
Jul 30, 2021
244
136
F3V4+837
There may be an issue with the Aluminum wiring. Aluminum wiring should not be used to wire receptacles. Aluminum wire is commonly used for service wiring, running wire to a sub panel. Due to the special wire termination requirements Aluminum wiring should not be used for wiriing receptacles. You need an electrician to determine what should be done.
This is a new condo built in 2019 here in California, not sure what the code is but apparently that's the wire being used between the breaker and receptacle..
 
Short answer: what you have will work perfectly with the 32 amp mobile connector, and nothing more is needed.
Agreed, but with one caveat: if you're planning on unplugging the mobile charger to take it with you when you drive, you'll want to check your receptacle model. If it's a residential-grade (vs commercial grade), be aware that it's not designed for large number of plug/unplug cycles, likely loosening over time, as most 240V residential plugs are used for fixed equipment. Should be fine if you're planning on keeping the mobile charger in place, however.

If you have the budget, keeping your 14-50-enabled mobile charger onsite, and buying a second one for traveling, isn't a bad idea. I also keep a pair of 12/3 extension cords in the frunk - one 25', one 50' - to give me a little more peace of mind and quiet down my (most likely irrational at this point) range anxiety.
 

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