So let's talk long term

[Phoenixhawk101]

So my wife and I are both pretty confident that Electric cars are here to stay, if not the absolute way of the future. We have agreed to purchase our first Tesla (Model S) in the next few months and since her car is still fairly new we are making plans to purchase the family's Model X likely in 2020. As we plan things out and look at what is realistic we realise that there is a high likelyhood that our oldest son may end up with a Model 3 (or maybe the Model Y) sometime around 2024 (only 8 years out....wow).

We currently live in Chicago, which means all of the kitchen and the dryer run off natural gas. This means that the number of 220 lines in the home are pretty scarce. So we will be hiring an electrician in the next few weeks to install a new panel box and run the lines.

So here is the question. Considering we may be looking at Three electric cars in the next 8 years, all being powered from the garage what sort of Amp ratting should we tell the installer to build the system to handle? Run three separate lines at 80 amp each? Or run one massive line for all three cars?
Thoughts?

 

[AEdennis]

...
So here is the question. Considering we may be looking at Three electric cars in the next 8 years, all being powered from the garage what sort of Amp ratting should we tell the installer to build the system to handle? Run three separate lines at 80 amp each? Or run one massive line for all three cars?
Thoughts?

If you go all 3 Teslas...

Then, get the new HPWC from Tesla... You can actually chain up to four chargers together.

My solution @ home is to have four plugs. One J1772, two NEMA 14-50 and one NEMA 6-50.

 

[KJD]

I would install 1 wall connector on a 100 amp breaker. On the new wall connector design you can put 4 of them on 1 breaker and they will share the load between them. There is no need to run 3 separate lines.

Tesla — Wall Connector with 24' Cable

The Model S has so much range that I only plug mine in maybe twice a week anyhow.

 

[Discoducky]

Three separate 80AMPS would do it. But it depends if you want to go full bling with three HPWC's or go low budget with 3 14-50's. My 14-50 diy was a total of $20 breaker and receptacle from amazon, $10 of Romex, junction box and outlet cover from Home Depot and an hour of labor (going strong for 3 years).

 

[GBleck]

Don't the 80 amp outlets require 100 amp lines and breakers as they are continuous loads?

Oh and for people who don't live in cook or lake county Illinois, we run conduit for all residential electric. Just FYI.

 

[FlasherZ]

Yes, the circuit must be rated at 125% of the charging current. So fi you want to charge at 80A, you install a 100A circuit. If you are ok charging at 64A, you install an 80A circuit, etc. And yes, the unions thank you for your contribution to their trade through the conduit rules.

There are a number of options you have. If you want to be able to charge them simultaneously and your service has the ability to handle it, installing the full current and conductors for it makes the best future-proofing. At my home, I have 400A service and my load calculations do support two HPWC's running simultaneously, so I have 2 100A circuits running in the garage.

Some homes only have 200A service, though, and can only support a single HPWC - or worse yet, a lower current rating. In that case, you have the ability to run a single 100A feeder (or whatever will be allowed) to a subpanel in the garage, and then connect up to 4 identical branch circuits, one each to a HPWC on the wall. Connect them together and they will share the current provided among multiple cars based on the state of charge. This way, if you have only 100A to give to EV charging, you'll make the most use of it when the cars need it.

Most homes won't have the ability to install 3 HPWC's at full current. To guarantee overnight charging for three heavily-used vehicles, I might target having 2 HPWC's worth of current available, then install one primary and one set of two shared. Put your heaviest-use vehicle on the primary and the other two on the two shared units.

 

[strider]

Depends on your usage. Batteries will only get larger in the future so unless all 3 cars are driving hundreds of miles/day you won't need to charge all of them every night (my wife and each commute ~50 miles/day and we take turns charging - house only has 100A service). I would concur with the others saying to run 1 100A line (80A continuous) and daisy-chain 3 HPWC's (assuming you have a 3-car garage?).