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Tesla Wall Connector amp limit

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I have a LR RWD Model 3 that states on my display that the max charge amps are 48 A. When my electrician installed my wall connector, he put in a 40A breaker. If I leave things alone, the charger will charge at the full 40 A so I have dropped the max charge amps to 39 A to include a 1A "factor of safety" - I am a little uncomfortable maxing out the circuit. My questions are:

1. Is this worth doing? Or should I just let it max out and charge at the full 40 amps?

2. Should I call the electrician back and ask him to install a 50 A or 60 A breaker so that I can charge at the full amps the car can do? Is there any advantage to charging at the lower rate? I assume my electrician installed the 40 A breaker because that's what he thinks my circuitry can safely handle.

Thanks!
 
What kind of wall connector, the Tesla one or a 14-50 outlet that the UMC2 that came with the car plugs into. You shouldn't draw 40 amps on a 40 amp breaker. If it's a 14-50 outlet the breaker should be 50 amps. If it's a Tesla wall charger that's wired directly I think it should be 60 amps which will yield 48 amp charging.
 
See the install guide here: https://www.tesla.com/sites/default/files/80A_Wall_Connector_Installation_Manual_EN_JP_ES_0.pdf
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All the answers so far are correct.

The electrician may or may not just be able to swap the breaker. I can't imagine why he'd put a lower amperage breaker in unless he used wire that was incapable of carrying more current. I'd even be concerned whether the wire he did use was sufficient for that breaker.

The rules on continuous load are there for your safety.
 
I am sorry, my big mistake. I looked again, and he has a DOUBLE 40 amp breaker, see pic. So that should mean I can do the full 48 amp charging, is that right? He told me he checked the wiring and I saw him going step by step through the book. He told me this was the third wall connector for a Tesla vehicle he has done.

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I am sorry, my big mistake. I looked again, and he has a DOUBLE 40 amp breaker, see pic. So that should mean I can do the full 48 amp charging, is that right? He told me he checked the wiring and I saw him going step by step through the book. He told me this was the third wall connector for a Tesla vehicle he has done.

View attachment 359970

No. The fact that it is "double" 40 amp means that it is 240 volts instead 120 volts. It is still a 40 amp breaker which means that you will be limited to 32 amps when charging. You need to determine what size wire was used either by asking the electrician or opening your panel.

I might speculate that the electrician confused the 32 amp mobile charging specs with the wall unit specs.
 
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No. The fact that it is "double" 40 amp means that it is 240 volts instead 120 volts. It is still a 40 amp breaker which means that you will be limited to 32 amps when charging.

The first time I charged at home, I watched it go all the way to 40 amps (40/40) and it stayed there, which is what made me uncomfortable. So, what I gather from all the other posts, I should definitely ramp it down to 32 amps in order to safely charge on my circuit.
 
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The first time I charged at home, I watched it go all the way to 40 amps (40/40) and it stayed there, which is what made me uncomfortable. So, what I gather from all the other posts, I should definitely ramp it down to 32 amps in order to safely charge on my circuit.

Rather than change it in the car, you should change the setting INSIDE the Wall Connector NOT in the car software. You can do this yourself. Change the dial inside the Wall Unit to #6. Then the Wall Unit will be protecting the wiring permanently rather than relying on the software setting in your car. The Wall Connector will communicate the max amperage to the car and you will not have to change the car setting yourself.
 
Again, a bunch of good answers here... your HPWC is set incorrectly, and should be tweaked down(on the rotary dial inside the HPWC) to the 32 amp setting (arrow toward number 6). This keeps the HPWC from exceeding 32 amps, which should keep your circuit breaker from nuisance tripping and your wires becoming dangerously hot.

Yes, you >could< do it on the screen in the model 3, but then someone comes over and plugs some other Tesla in, or your wife gets impatient, and so on....
 
I have a LR RWD Model 3 that states on my display that the max charge amps are 48 A. When my electrician installed my wall connector, he put in a 40A breaker. If I leave things alone, the charger will charge at the full 40 A so I have dropped the max charge amps to 39 A to include a 1A "factor of safety" - I am a little uncomfortable maxing out the circuit. My questions are:

1. Is this worth doing? Or should I just let it max out and charge at the full 40 amps?

2. Should I call the electrician back and ask him to install a 50 A or 60 A breaker so that I can charge at the full amps the car can do? Is there any advantage to charging at the lower rate? I assume my electrician installed the 40 A breaker because that's what he thinks my circuitry can safely handle.

Thanks!

Others have this pretty well covered but I will recap and add some pieces:

This was done wrong. There is no way around that. Even if the wire is good for say 50 amps, by setting the Wall Connector wrong, your electrician has created a situation that will likely result in nuisance trips of the breaker as they are not intended to operate at 100% for extended periods of time.

NEC says that all EVSE’s are “continuous loads” and that you must size the circuit as if the load was 125% of what it actually is (hence people saying the 80% derate which is the inverse of 125%).

The real concern here is that let’s say your electrician only ran say 8 awg romex which is only good to 40 amps (32 amps continuous). Running it at 40 amps continuous takes away that safety margin. I would not do it period.

If you were in a pinch and needed a solution for a day or two I would charge manually at 32 amps using the display screen, but this is *not* a long term solution. As others have stated, you could do the work yourself to tweak the dip switch down by one setting, but I personally would not want to have paid for a wall connector only to get just 32 amps out of it...

The real questions are:

What kind of wire was installed? Romex (NM cable) or something like THHN in conduit? What AWG (size) was it?

Does your “service” (breaker panel) have sufficient ampacity to support a circuit larger than 40a?

What was the agreement with the electrician for? Did they commit to install any particular size circuit? Or was it just to “install the wall connector”? If so, they may have fulfilled their contractual obligations (other than to set the dip switch correctly which is a trivial change).

If I were you, I would optimally want a 60a (or even higher) circuit installed. This is what I have and I love it. My M3 charges so fast!

(though 32 amps may be completely sufficient for your needs)

P.S. Your electrician may need to go back and check any other units they installed this same way. I am not sure how to politely point that out to them.

P.P.S. We are also assuming that the wire is of sufficient ampacity for even 32 amps continuous. We have no evidence of that and very little confidence in your electrican based on the double whammy of only installing a 40a breaker AND setting the dip switch wrong.
 
IN his defense I originally ordered the mid range M3 which charges at the lower rate, so the 40 amp breaker should have sufficed. I seem to remember him telling me he was setting the switch for 40 amps so it should have been right. The wiring used was for a 240V outlet for a large freezer which was in the garage for the former owner of the house and the wall connector is right next to the breaker box. Knowing that, would I still need to upgrade the wiring to take advantage of the faster rate of charging (install a 60 amp breaker)? Perhaps the 40 amp is indeed good enough.
 
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IN his defense I originally ordered the mid range M3 which charges at the lower rate, so the 40 amp breaker should have sufficed. I seem to remember him telling me he was setting the switch for 40 amps so it should have been right. The wiring used was for a 240V outlet for a large freezer which was in the garage for the former owner of the house and the wall connector is right next to the breaker box. Knowing that, would I still need to upgrade the wiring to take advantage of the faster rate of charging (install a 60 amp breaker)? Perhaps the 40 amp is indeed good enough.

Large freezers (assuming it isn't a walk in type) are rarely on circuits greater than 20a. I would try to understand more about this installation for your safety.

I assume it was not inspected?
 
Large freezers (assuming it isn't a walk in type) are rarely on circuits greater than 20a. I would try to understand more about this installation for your safety.

I assume it was not inspected?

True dat. My Nissan Leaf Aerovironment charger was on the breaker for the past seven years so no inspection was required in our town.
 
True dat. My Nissan Leaf Aerovironment charger was on the breaker for the past seven years so no inspection was required in our town.

What rate does the leaf charge? Was it plugged into the refrigerator outlet? What type of plug was on it before the HPWC was installed?

Personally, I'd like to know the gauge of the wire, just to be safe, to determine what rate you should charge at or if the wiring should be replaced.