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Replacing 50 amp breaker with 60 amp?

Guys, simple answer: do no do it.
High Risk just to save some time. Main difference on EV charging is that the car will draw that current CONSTANTLY for several hours. The cable will overheat, maybe the first couple of times you wont see a problem but eventually the degradation of the materials running outside their approved temps will lead to failure.

The correct way is to replace the wiring to a higher spec, specially taking into consideration the distance from the breaker box.
 
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I was obsessed with getting max charging at our cabin and considered rewiring for 60 amp, but have literally only wished for faster charging once or twice. My current setup is 50 amp breaker and I charge at 42 amps which is good for 37 mph, so plenty of charge in 4+ hours (plus Supercharger 20 miles away in Leavenworth).
 
I was obsessed with getting max charging at our cabin and considered rewiring for 60 amp, but have literally only wished for faster charging once or twice. My current setup is 50 amp breaker and I charge at 42 amps which is good for 37 mph, so plenty of charge in 4+ hours (plus Supercharger 20 miles away in Leavenworth).
Ha, sounds exactly like my situation. This is a lake house/cabin property and I'm also obsessed with getting max charge! :p
 
The wire (6 gauge UF-B or NM-B) is rated to 55A. The wire being limited to 55A is the limiting factor not the 60A breaker. Whenever charging an EV the rule is to always derate the circuit to 80% of the rated maximum amperage, so 44 amps would be the maximum when charging in this case. If the Tesla Wall Connector could be configured for a 55A circuit then charging using the Wall Connector would be limited to a maximum of 44 amps. Since the Wall Connector does not have a setting for a 55A circuit the next lowest setting must be used. In this case the Wall Connector would be correctly configured when set for a 50A circuit. This would enable charging at a maximum of 40A. (40A is also your current charging amperage with the current wiring.)
Looking at this brings up another question and/or issue. What size conduit is this 6-3 UF-B Romex in? (btw: I am glad her electrician used the UF-B and not the NM-B)
 

ATPMSD

Active Member
Mar 12, 2021
2,007
1,930
Atlanta, GA
Looking at this brings up another question and/or issue. What size conduit is this 6-3 UF-B Romex in? (btw: I am glad her electrician used the UF-B and not the NM-B)

Romex does not require a conduit, except on an exposed wall typically less than 7-feet in height. Just curious as to why are you glad the electrician used UF-B and not NM-B? UF-B can be buried while NM-B cannot. Was their another reason?
 

terranx

Member
Aug 29, 2019
793
1,141
USA
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.
The exception to this is that the wall connector can be configured to 44A if using power sharing. Tested this a while back out of curiosity (right now I actually have it set to split 52A as per the capacity of #6 THHN)
 

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Rocky_H

Well-Known Member
Feb 19, 2015
8,757
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Boise, ID
The exception to this is that the wall connector can be configured to 44A if using power sharing. Tested this a while back out of curiosity (right now I actually have it set to split 52A as per the capacity of #6 THHN)
Wow, what?! I did not know the Tesla wall connectors could be set for a 44A limit now. I thought they always had to be set for the more round numbers of 40 or 48A to correspond with the 50 and 60A circuits.
 

terranx

Member
Aug 29, 2019
793
1,141
USA
Wow, what?! I did not know the Tesla wall connectors could be set for a 44A limit now. I thought they always had to be set for the more round numbers of 40 or 48A to correspond with the 50 and 60A circuits.
Well it’s a little bit of a hack. When you enable power sharing, it lets you set a network wide limit in 1A increments. So if you have the individual power connectors set to 48, but the network set to 44, it sets everything to 44. I couldn’t figure out a way to pull that off with just one power connector
 

bradtem

Robocar consultant
Dec 18, 2018
932
1,063
Sunnyvale, CA
This is beyond silly. At 40 amps 240v you can add 37.5 miles per hour to your car. In an overnight charge of 8 hours that's 300 miles. Have you ever added 300 miles in one night? Have you ever only parked the car for 8 hours? You didn't get that much sleep that night, I guess. Have you ever gotten even close to this? The average car needs only 10kwh per day. It can get by on Level 1 with 1.4kw! It won't get full every day but it has a very low chance of ever getting empty. On that 1 day a year it happens, you go to the supercharger. People are shocked to learn that level 1 is OK for most drivers. For above average drivers, 3kw is usually more than enough.

So why put a lot of effort in getting to 11kw? Even if you think a day might come where you will pull in almost empty and need to get to full after 7 hours of sleep (you should not generally do either of those things, it's not good for the battery) you can stop by a supercharger for a few minutes. Any supercharger. You will be almost full and need just a mild touch up on that one day in 10 years this happens.

So maybe you think you want to pop home for just a few hours and get just a few more miles during the stop. I guess you could want that, but do you need it? As others have explained the rating of your wire and breaker is for short duration current. All of it is only rated for 80% of that max on charging current that will last more than 15 minutes. A 50 amp breaker is supposed to blow if you put more than 40 amps through it for more than 15 minutes. It will probably take more than 50 amps for several seconds, but should blow if it gets 51 amps for more than several seconds.
 

rjpjnk

Active Member
Mar 12, 2021
1,382
982
NJ
This is beyond silly. At 40 amps 240v you can add 37.5 miles per hour to your car. In an overnight charge of 8 hours that's 300 miles. Have you ever added 300 miles in one night? Have you ever only parked the car for 8 hours? You didn't get that much sleep that night, I guess. Have you ever gotten even close to this? The average car needs only 10kwh per day.
I get your point, but I don't think it is silly. One could just as easily argue "Do you really need a car that can go 0-60 in 4 seconds for everyday driving? How many times did you have to go that fast on the highway?" It's the same sort of argument. We don't *need* either of these things, we just enjoy them because they are possible and fun.
 

rjpjnk

Active Member
Mar 12, 2021
1,382
982
NJ
That's pretty much why I downrated my wall charger to 30A ... well I really did it because of a load calculation I did, but it's why I have no problem with it being downrated

30A is more than enough for me!
Same here. I charge at 40A even though I could go to 48A. I figure lower current is a little less stress on everything, and I am not in any hurry. 30A would be fine as well.
 

bradtem

Robocar consultant
Dec 18, 2018
932
1,063
Sunnyvale, CA
I get your point, but I don't think it is silly. One could just as easily argue "Do you really need a car that can go 0-60 in 4 seconds for everyday driving? How many times did you have to go that fast on the highway?" It's the same sort of argument. We don't *need* either of these things, we just enjoy them because they are possible and fun.
You don't. Mine takes 5.1 seconds. I almost never use that. With the Tesla's design, it sort of comes with it. I do use that power not from dead stops but on the highway when passing etc. In fact, I would prefer to tune the car to give me more power at 60mph and less at 0, the electric motors naturally are best torque at 0.

What is silly is going to major lengths or cost or risk of going beyond the tolerances of the electrical code to get above 40a. If you had 2 cars, you might think about it, but frankly 40a is enough for 3 cars, because even though you might drive one car to empty 2 days in a row, you don't drive all 3 of them. Even 3 people who all have a 100 mile RT commute would only start to push a need over 40a.

What you learn when you charge with Level 1 (1.8kw 20a) as I did for 2 years is that it's no big whoop to not get to full. The bigger your battery, the less charging speed you need -- something that is counter to most people's intuitions -- because you can tolerate not getting to full for a few days. What mainly matters is are you charging long enough to do just a bit better than your average usage, because eventually you will get back up to full that way. Those very rare days it dips too low can mean a short supercharger visit.

Now don't get me wrong. This is what you *need*, it's a minimum, and it doesn't mean more isn't nicer and a bit more convenient. But it does mean you don't want to go nuts. It should never be necessary to do things like upgrade your panel and service to have an EV, though under today's electrical code you sometimes do. (In the future, we'll see cars and EVSEs designed to track the usage of other loads in the house, and moderate the car's demand, so that the car stops charging when the air conditioner, dryer and oven all go on in the middle of the night, which they don't.) If we get the electrical code to accept that, there's plenty of power to charge your car.
 

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