100A Upgrade

100A Upgrade

I am in the process of buying a new home. The builder is offering a 100A connection including panel upgrade for $900. He is also offering a 50A connection for $700.

I am thinking of going with the 100A connection as that would give me an upgraded panel but I am not sure how the connection is terminated in the garage.

I am thinking of having an electrician come after I buy the home to put a sub panel with two 50A breakers on this 100A line and have 2 NEMA 14-50 connections to charge two cars.

Does anyone know how much does that cost to install a sub panel and 2 NEMA 14-50 connectors.

If that is too much $$, I can just go with over NEMA 14-50 and call it a day with the builder.

Any suggestions?


bp | 23. Dezember 2018

When we built our house 4 years ago, we had them install a 150A box running a 100A circuit for charging one car and a 50A for the other.

Another option would have been to install a 100A box and have two HPWC's sharing a 100A circuit - since the HPWC's will communicate and share the same circuit, similar to how a Supercharger shares one charger between two cars.

Though... Even with S/X 100 battery packs, a 14-50 outlet, using Tesla's 14-50 connector or an HPWC should fully recharge overnight, and you really only need more than a 50A circuit if you're trying to faster charging during the day.

Scottsdale100D | 23. Dezember 2018

I would suggest to do everything while your home is being built. Ask the Tesla charging department for specs based on your requirements so you can pass along to the builder. $900 is a bargain.

What will help you the most is to be crystal clear on what you want. If the builder would be willing to install the HPWC(s), then even better. Ensure they have the specs and your requirements documented. Enjoy!

Tesla2018 | 23. Dezember 2018

See if they can install the panel in the garage near where the cars will be located. I lucked out since my panel is on the same side of the 3 car garage where the car is. I only needed to run about 2 ft of wire to put in the 240 volt outlet.

I used to live in a condo that was built into the side of a hill. The bottom floor was even with the bottom of the hill and the decond floor was the garage area that was at street level and then it had a third floor above it. The panel was on the bottom level at one end of the condo and the garage was on the second level at the opposite end. It would have cost a fortune to run wires from the panel to the garage and have it go between floors that didnt have an attic between them.

stevencsimpson | 24. Dezember 2018

I have a 32amp setup and have never needed anything more. If you think you are going to need the miles available to you always day or night then possibly it would make economical sense. If you're
a heart surgeon on call or Elon that has to dash to the plant at a moments notice...!

kcheng | 26. Dezember 2018

$900 for "offering a 100A connection including panel upgrade for $900" seems expensive. I mean, my electrician wired my whole house for $2000, with a 200amp service. Of course, he was a childhood friend, and I helped him, and gave him $1000 extra, but still.

Not sure what's actually being added for a 100amp connection. Is it a 100amp junction box in your garage? So, basically running the appropriate size cable to a box? How long is the wiring run? Not sure what the panel upgrade is, because new homes should be 200amp at a minimum.

As for the OP's question, if there's a 100amp junction box in the garage, that you already paid $900 for, then it's simple for an electrician to wire up a small sub panel to handle a couple NEMA 14-50 boxes. The boxes are $30 each. Wire plus conduit depends upon how far away the boxes are from the sub panel.