Choosing between 32a plug-in and 48a hardwired

[Fat Mach]

most likely you can run your main house and ADU with your existing 200a service. you might have to add a sub-panel and tandem a few branch circuits to make room for a 100amp subpanel to ADU

stepping up to 300a+ service is a big deal, and likely to cost $5k-$10k because extra engineering reviews, permits, and likely new conductors on the utility side are required... assuming your nearest transfer and line can support the added capacity

stick with your 200a service if possible! add subpanels if you can.....

Since he says he’s in a rural area, there are probably no permits or inspection involved. That’s how it is here. However, the utility likely won’t let you upgrade the service to 320 without justification such as a new load calculation showing that what you are adding necessitates upsizing.
I agree with you, his 200 is likely adequate.

OK, thanks guys! I'm in Santa Clara County so permits would likely be required. Since the ADU was built without permits, prior to my buying the property- I really don't want any county inspectors coming out. I'll try it as-is and see if anything trips.

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[Mach-Lee]

I was lucky that the house I moved into had a full 100A subpanel that was mostly open. I hardwired my ChargePoint Flex. I see about 43mph @ 11kW charge rate set at 48A. The unit cost me $700, but comes with a 14-50 dongle if you want to plug it in and step down the current. The install only cost me $250 in this house because I mounted the EVSE about a foot from the panel.

I’d be careful about charging at 48A on a 100A panel, you could easily be overloading your main panel when you are using other appliances like A/C and a dryer or oven. I would set to 32A if you only have 100A service.

Loads vary significantly, but for a very rough estimate figure the other loads in your house add up to 50A. You don’t want to exceed 80-90% of your service rating after adding together your loads. There are more exact calculations that can be done but 50A+charger amps will give you a rough idea.

On the flip side, a 200A panel should handle dual 48A chargers just fine, no need to upgrade.

 

[Davedough]

I’d be careful about charging at 48A on a 100A panel, you could easily be overloading your main panel when you are using other appliances like A/C and a dryer or oven. I would set to 32A if you only have 100A service.

Loads vary significantly, but for a very rough estimate figure the other loads in your house add up to 50A. You don’t want to exceed 80-90% of your service rating after adding together your loads. There are more exact calculations that can be done but 50A+charger amps will give you a rough idea.

On the flip side, a 200A panel should handle dual 48A chargers just fine, no need to upgrade.

I misspoke. I have a dedicated panel just for the charger. There isn't anything else that shares the panel with it. I have an additional 200A panel that the rest of the house is powered from. The previous owner had the second main panel installed to power a large whole house generator that he took with him, so I was able to use that to isolate the charging

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