I just got a 50 amp breaker in my sub panel to feed by 8 gauge wires to Nema 14-50 installed. When I charge with the supplied mobile adapter I can see it draws only 32 amp. I was thinking it will draw 40 amp. I cannot up the amperage on the screen either. Any reasons you guys can think of?
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Help: 50amp 240v limiting to 32 amp only
- Thread starter JoganJani
- Start date
If you read the home charging section of Tesla’s web site the options and the amps for each are explained clearly.
Home Charging Installation
Home Charging Installation
For one, in Canada they can only draw 32A max. Another, too many NEMA 14-50s are installed on 40A circuit breakers. Thirdly, early models of Gen1 chargers melted plugs and outlets when drawing full power.
32A is listed in the owners manual and most likely on the charger unit itself. https://www.tesla.com/sites/default...bile_connector_owners_manual_32_amp_en_US.pdf
eprosenx
Active Member
I suspect that moving from 40a down to 32a also allowed them to make the UMC Gen 2 slightly smaller/lighter and probably cheaper than the old UMC Gen 1. As others mentioned, it seems to have added a margin of safety for electrical jobs that were not up to snuff. It is generally legal to have a NEMA 14-50 receptacle on a 40a branch circuit. The highest current "continuous load" allowed on a 40a circuit is 32a. All EVSE's are considered "continuous loads". While what should happen is a breaker should blow if things go wrong, but there is always the chance that something goes wrong and it causes a fire instead.
Note that I think they still sell a version of the UMC Gen 1 that has a fixed pigtail Model S/X Corded Mobile Connector I don't see it documented anywhere, but I suspect this can still do 40 amps.
But yeah, if you want more than what the UMC Gen 2 will do, I would probably just install a wall connector. That is what I did.
I was going to say that, but I already told two posters today to RTFM in response to other questions and it’s getting kind if tiring to keep repeating that.Thanks Guys. I better RTFM
But really, new owners NEED TO RTFM. This is unlike any other car you have ever owned.
eprosenx
Active Member
Also: What kind of wire was used? If it was NM wire (Romex) then this is not a compliant installation. You have to use the 60c rating with NM cable which would only allow 8awg to handle 40 amps (32 amps continuous). If using THHN in conduit (as an example) then 8 AWG is good for 50 amps (40 amps continuous).
Yes, the corded mobile connector does supply 40A, so it could handle this. But really, if you're going to buy an extra something, I would instead just get a wall connector for about the same price.
I walk on eggshells around here, because the uptight moderators smack people down way too easily, but I really respect your willingness to tell people to RTFM.
TexasEV is absolutely correct in pointing the need to RTFM. I took his advice awhile back and was not at all surprised when my 14-50 on a new 50 amp breaker only drew 32 amps.
You will find an awful lot of advice on these forums that is not correct.
For anything electrical this is a good source of information.
FAQ: Home Tesla charging infrastructure Q&A
henchook
Member
Just installed black signature wall connector, on a 50A breaker on the sub panel (with the selector pin properly set to #8 for 50A breaker).
According to this chart Wall Connector the Model 3 should charge at 40A and add 37mi/h range, but the car shows only 32A max (approx 28-29mi/h).
Is this right? Why can't I charge at 40A?
According to this chart Wall Connector the Model 3 should charge at 40A and add 37mi/h range, but the car shows only 32A max (approx 28-29mi/h).
Is this right? Why can't I charge at 40A?
Unless you have LR Model 3 you're limited to 32amp. LR can do up to 48.
timk225
Active Member
Your Model 3 will charge at up to 240 volts at 48 amps if you're at a HPWC that is wired to allow such a load. 60 amp breaker required, and 4 or 6 gauge wire. I think that's a 45 mph charge rate.
Most HPWC's I've tried are on one leg of a 480 volt 3 phase power supply, so 208 volts, and more like 198-205 volts at the car. 32, 40, or 48 amps are charge rates I have seen.
Most HPWC's I've tried are on one leg of a 480 volt 3 phase power supply, so 208 volts, and more like 198-205 volts at the car. 32, 40, or 48 amps are charge rates I have seen.
Your mid-range Model 3 can charge at a maximum of 32 amps. Long range can do up to 48 amps.
Hopefully that's THHN wire in conduit... as was stated earlier in the thread, #8 romex(NM-B) is not allowed to have a 50A breaker.
Similar threads
- Question
