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How many amps are you going with for your Model 3 home charging circuit?

How many amps are you going with for your Model 3 home charging?


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    88
I thought I was future proofing my home when I put in a 100 amp sub panel. Wish I had more. Two cars, electric water heater, lights, fans, la-de-dah and I'm sitting at 100 amps. I figured that charging from 8PM when the rates drop I can easily charge the cars at 24 or 32 amps on my 50 amp Tesla charger. They always get full, but I don't run them to empty hardly ever. There's no need for even 40 amps. I dial the cars down and they take what I ask them to, works great.
 
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Doug_G

Lead Moderator
Global Moderator
Apr 2, 2010
17,888
3,410
Ottawa, Canada
I don't have a 3 coming, but having driven Teslas for 8 years now I have a little experience with charging.

I have both 90A (70 usable) and 50A (40 usable) charging stations in my garage. I almost always charge at 40A.

I might use 70A a couple of times a year. That was true even when I was plugging the Roadster into the 70A station daily. It was more efficient charging at 40A, and I rarely needed faster than that.

As for less power... I've had occasional nights where 30 would not have been enough for a full charge. Of course that's really only an issue if you need a full charge the next day, i.e. back-to-back road trips. On a few occasions I've needed the full 70A to be charged in time, but that's much less less of an issue now that there are Superchargers.
 
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Rockster

Active Member
Oct 22, 2013
3,022
4,708
McKinney, TX
Your poll doesn't allow for high enough amperage. We have two HPWCs, sharing a 100-amp circuit. If a person's home has the power capacity there's no reason to restrict the circuit to a specific vehicle. It's better to future proof the setup.

Now, we can charge at 80 amps continuous using either charger, or share the circuit as we need.
 
Just installed my HPWC....I already had a 100 amp sub panel in my garage from my Chargepoint install. I have a 40 amp breaker on the chargepoint and a 60 amp on the Tesla HPWC.
A little crowded putting them both between my garage doors, I may end up moving them someday.


That's what I'll be doing too. Installing a 100amp sub-panel in the garage and probably dedicate 60 for the Tesla HPWC and leave 40 for a future EV.
 
Load calculations allow provisioning more total load than the panel is rated for, on the assumption that you will rarely run everything at the same time. My last home had 100A service with two 30A breakers for dryer and AC and a 50A breaker for the oven. That's 10% over the panel's 100A capacity before adding any other loads. But the actual draw from each of these circuits is below even 80% of the rated capacity and they are rarely all running at the same time so the 100A master breaker was never tripped.
 

MorrisonHiker

Well-Known Member
Moderator
Mar 8, 2015
10,551
10,578
Colorado
Do you folks with dual chargers have 400A service? I'm just not sure how you keep your total load under the 80% mark without load control devices. Or did no-one check the load calculation?

For me, house area + AC + dryer + well pump (12A, 240V)+ 40A charger maxes my 200A service.
The Gen2 WCs are load balanced and can share a circuit. This summer, we'll be installing 3 load-balanced WCs in the garage, replacing 2 14-50 outlets.
 
Load calculations allow provisioning more total load than the panel is rated for, on the assumption that you will rarely run everything at the same time. My last home had 100A service with two 30A breakers for dryer and AC and a 50A breaker for the oven. That's 10% over the panel's 100A capacity before adding any other loads. But the actual draw from each of these circuits is below even 80% of the rated capacity and they are rarely all running at the same time so the 100A master breaker was never tripped.
Yep, well aware. It's the continuous loads that count...my total is well higher than 200 too... You should see how many circuits and breakers I have...
 
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Do you folks with dual chargers have 400A service? I'm just not sure how you keep your total load under the 80% mark without load control devices. Or did no-one check the load calculation?

For me, house area + AC + dryer + range + well pump (12A, 240V)+ 40A charger maxes my 200A service.

I have 200 amp service. I am pushing the upper limit of my panel with a 40A (32 actual charge) Chargepoint EVSE and 60A (48A actual charge) Tesla HPWC. But even with a 3600 sqft house with a pool, I am able to make it work.
 
I have 200 amp service. I am pushing the upper limit of my panel with a 40A (32 actual charge) Chargepoint EVSE and 60A (48A actual charge) Tesla HPWC. But even with a 3600 sqft house with a pool, I am able to make it work.
Your numbers should be very similar to mine, so very surprised you aren't considered over. With the chargers and the home area, you would only have about 9000 watts remaining of the 38400 watts allowable on a standard 200 A service.

So 9000 watts for stove, pool pump, central heating, AC, hot water and dryer isn't typically anywhere near sufficient if all electric.

So assuming you have gas heating, gas dryer, gas hot water and a gas stove, you might just be marginal.

Do you know if a load calculation was done when your chargers were installed?

If you want to run one yourself, here's an easy to use calculator: CEC Electrician Calculators

(I'm mostly bummed because I'm (officially) capped at 40A total load for car chargers. Just don't know how others are 'getting away' with more.)
 
40amp is plenty. I have invested in hpwc and 80amp wiring thinking that I'll make it future-proof while keeping the old box and dialling down hpwc for now. Guess what, it's been 5 years and I never needed more. Now with Model 3 joining the family might need to add another 40 amp HPWC and upgrade the house to 200 amp.
 

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