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Which electrical charger installation proposals should I pick?

Hi all, I live in Chicago and am looking for electricians to install a 240V outlet in my detached garage for a Model Y expected at EOY. I got several proposals and eliminated them to two of the ideal ones. I know nothing about electricity so I am looking for some advice on which one to pick:

Background: Total 100 AMP with limited to no extra spaces in the panel.

First Proposal: $1,500 for a panel swap with a new Siemens 100 AMP, 32-space panel, and $2,500 for the power brought to the garage via underground pipe. Total: $4,000

Second Proposal: Install a new sub-panel and power brought to the garage through the roof. Total: $3,352

Based on my research, I should choose the second proposal because it is safer and cheaper to install a sub-panel; however, I do have a problem with my current panel where occasionally my lights dim or flash during the winter when my furnace is on, so I am debating on the first proposal as well. Can someone please give me some suggestions?
 

SageBrush

REJECT Fascism
May 7, 2015
14,161
19,690
New Mexico
First Proposal: $1,500 for a panel swap with a new Siemens 100 AMP

I doubt you understood correctly. While it is possible that the Electric service drop is 100 Amps, it is not likely. Start there, since a beefier service will allow a new panel with a higher Amp rating. Current NEC code requires 100 Amps to multi family dwellings, and 200 Amps to single family homes. Staying with a 100 Amp panel and charging an EV is possible but it amounts to putting a square peg into a round hole. If you plan to stay in that home for years, consider upgrading the service panel to 200 Amps, presuming the service allows.

Your dimming lights is an overloaded branch circuit issue, not a matter of the service panel 100 Amps.

Your take that a sub-panel choice is the basic question is a red herring since it doesn't matter whether you add a breaker to your service panel to go to the EVSE receptacle, or add a breaker to the service panel to power a sub-panel and from there to a receptacle. Re-focus your decision on the home Amp service rating you want, the utility service feed allows, you are willing to pay for, and go from there.
 
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SageBrush

REJECT Fascism
May 7, 2015
14,161
19,690
New Mexico
TLDR

I would like to suggest the SPAN electrical panel and SPAN drive if $$$ is not quite a concern.

No, I don't have it.

The SPAN panel attempts to circumvent load calculations by enforcing a maximum load. It is a very interesting idea, but it does not break the laws of physics, and it does have to be accepted by your local regulatory authority.
 
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qdeathstar

Completely Serious
May 17, 2019
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Hey @jcanoe, thank you so much for the information! This gives me a lot of confidence. I rarely drive; in fact, Model Y is my first vehicle. On average I drive about 20-40 miles a day and 60 miles at most.
Install a Nema 5-20 GFCI plug in the garage (and make sure wire and breaker can handle that) and you can charger at 120v/16amp and get about 7 miles of range per hour of charge.

Also go through your house and make sure you're using LED light bulbs everywhere and look at installing more efficient appliances (example: hot water tank). Spend your money reducing your electrical load, rather than increasing your capacity. Consider a shared outlet for your dryer, if you want to charge your EV at 240v.
 
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Rocky_H

Well-Known Member
Feb 19, 2015
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Boise, ID
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