Lotta people think the NEC is a design book. It is not. It is the bare minimum requirements for safety.
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Replacing 50 amp breaker with 60 amp?
- Thread starter MatildaModelY
- Start date
If I set the amperage on the app to 44amps which is a little higher, what’s the real problem running this on a 50amp breaker?
If the Wall Connector is configured for a 50A circuit I don't believe that the Tesla app or the vehicle charging screen will let you set the charging amperage higher than 40A; only lower. The charging screen may default to 48A but once you start to charge the Model Y and the Wall Connector or other EVSE will handshake and settle on a maximum charging amperage that is compliant with the charging circuit, i.e. not to exceed 40A (for a 50A circuit.) (When charging using the Tesla Gen2 Mobile Connector with the NEMA 14-50 power plug adapter the maximum charging amperage would automatically set to 32A.)
If you set the breaker to 60amp then in the app you can toggle amps to the car from 32 to 48.
I don't believe this is true. The Wall Connector (or other EVSE) calls the shots (sets the maximum charging amperage), not the Tesla app or the Tesla vehicle charging screen settings, as it should be.
I believe OP means "If you set the wall connector as if it had a 60 amp breaker...".
And yes, it would still be marginally okay to set the car amperage down to 44 with a 50 amp breaker, since the wire is rated to 55(times 80% for EV use). The minor problem with that is that every now and again, the Tesla will randomly forget that 44 and go back to 48 with no warning, like after a firmware update. IMHO, its still not really a danger because the breaker will trip before the wires will burn.
To set the charging amperage above 40A, and charge at the higher amperage, the Wall Connector would have to be configured for a 60A circuit. As @Sophias_dad noted the Tesla charging settings may revert to 48A the next time you charge even if you previously set a lower charging amperage. It is too bad that the Wall Connector does not support a setting for 55A so that charging would automatically be limited to 44A.
Pretty sure the breaker only breaks if you exceed the max amperage of the breaker (exceed 60A in this case). A breaker will happily let you burn your house down.
As I understand it the issue is continuous usage.
Because electric car chargers draw their current continuously for many hours on end they are treated more strictly and limited to only 80% of the rated safe current for the wire.
I know it seems unfair, and of course it would work at 48 amps even on the 50 amp breaker as mentioned, but the simple fact is it’s not permitted. Fortunately 40 amps still charges plenty fast, and may even have some advantages for your battery or longevity of you charger.
I’ll adjust back down to 40amp charging.
ATPMSD
Active Member
The “round up” rule does not apply to EV charging, there is a section in the NEC code that specifically addresses EVs. You cannot use anything higher than a 50-amp breaker unless the wire is rated at 60-amps. I do not have the code reference handy, but it is posted in a lot of forums if you want to look it up.
fiehlsport
Tire Guy
Correct. #6 NM (romex) is not permissible by code for 48A charging on a 60A breaker.
#6 THHN is.
ATPMSD
Active Member
EVer Hopeful
Active Member
... at less than the max conduit fill percentage 
(then we can talk about the max no of bends in the conduit)
(then we can talk about the max no of bends in the conduit)
EVer Hopeful
Active Member
Two pages and the most important question of all hasn't yet been asked
Why?
I mean I understand you want to get the most of of the appliance, but still, do you really need that throughput?
I installed mine and downrated it to 30A due to the results of a Load Calculation. It's not a bother at all, because mostly, I come home with a significant amount of charge, plug it in, then go to sleep for at least 8 hours. More than enough time to get the top up I need
Unless you're in and out of your house continuously and driving squillions of miles, maybe keeping things the way they are will be more than sufficient
...plus UF-B is a bugger to work with
OxBrew
Active Member
Agree. I set mine to charge at 32A, mostly to keep components in the onboard charger cooler (this is really unnecessary, but I'm just overly cautious). Most days topping up takes 1-3 hours, usually done before I go to sleep.
Twice in 7000 miles I bumped it up to 48 since I forgot to plug in the night before, and had to start a 350 mile trip across the state. No big deal. 40A is plenty.
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