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On Saturday, my wife is going to test drive a Model X. This will be for her car and not mine as I already have a reservation in for the Model 3. This will be our first time ever in a Tesla actually. Depending on how it goes, we might be placing an order for one. Though, who am I kidding... I don't really see her not liking it.

One of the steps that I was planning on doing down the line for the Model 3 was to get 100 amps to the garage for charging. I feel this will suffice for 2 EV's with the HPWC power sharing feature.

Our house has a 150A breakerbox and it is completely maxed out. My question is how an electrician will get 100A to the garage? Will the main breakerbox have to be upgraded to 250A-300A (in order to install a 100A breaker for the garage) or can the original 150A breakerbox be kept and a second 100A breakerbox be installed in the garage? I'm just curious if I "HAVE" to route the power through the main breakerbox due to some code or something. I know this can vary from state-to-state (I'm in VA).
 

BerTX

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May 2, 2014
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Texas/Washington
On Saturday, my wife is going to test drive a Model X. This will be for her car and not mine as I already have a reservation in for the Model 3. This will be our first time ever in a Tesla actually. Depending on how it goes, we might be placing an order for one. Though, who am I kidding... I don't really see her not liking it.

One of the steps that I was planning on doing down the line for the Model 3 was to get 100 amps to the garage for charging. I feel this will suffice for 2 EV's with the HPWC power sharing feature.

Our house has a 150A breakerbox and it is completely maxed out. My question is how an electrician will get 100A to the garage? Will the main breakerbox have to be upgraded to 250A-300A (in order to install a 100A breaker for the garage) or can the original 150A breakerbox be kept and a second 100A breakerbox be installed in the garage? I'm just curious if I "HAVE" to route the power through the main breakerbox due to some code or something. I know this can vary from state-to-state (I'm in VA).

Consult a licensed electrician, not a car forum.

Just because your main box is full of breakers does not necessarily mean it is "maxed out". That is calculated by load, not the number of breakers. That said, you probably WILL need to up the service, and probably put in a sub-panel in the garage slightly larger than what you need for the Wall Connector. They will likely run the sub-panel anyway, as you will need a switch in the garage to be able to shut it off locally.

Consult a licensed electrician.
 

Dwdnjck

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Mar 11, 2013
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First, look in you laundry room. Do you have an unused dryer plug , or plumbing for a gas dryer? It might be a lot simpler to buy a gas dryer and move the dryer plug. Unless you and your spouse both have a long commute, a 110 plug might even be workable on one of two electric cars. Remember, you don't start every day with a full tank in a gasoline car.
 
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Consult a licensed electrician, not a car forum.

Just because your main box is full of breakers does not necessarily mean it is "maxed out". That is calculated by load, not the number of breakers. That said, you probably WILL need to up the service, and probably put in a sub-panel in the garage slightly larger than what you need for the Wall Connector. They will likely run the sub-panel anyway, as you will need a switch in the garage to be able to shut it off locally.

Consult a licensed electrician.
Well no kidding I will consult a licensed electrician. I'm pinging a few people here. My question I guess is does the sub-panel require to be tied into the main panel or the cable between the outside meter and the main panel.

First, look in you laundry room. Do you have an unused dryer plug , or plumbing for a gas dryer? It might be a lot simpler to buy a gas dryer and move the dryer plug. Unless you and your spouse both have a long commute, a 110 plug might even be workable on one of two electric cars. Remember, you don't start every day with a full tank in a gasoline car.

My daily commute can range between 80-120 miles round trip for 2 locations I go to frequently. My wife has a 60 mile round trip commute. We will benefit from a dedicated 100A circuit for daily charging.
 

BerTX

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May 2, 2014
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Texas/Washington
Well no kidding I will consult a licensed electrician. I'm pinging a few people here. My question I guess is does the sub-panel require to be tied into the main panel or the cable between the outside meter and the main panel.

It will need to be tied into the main panel unless you have a separate meter installed.
 
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Zeroeth, make an estimate of how much charge capacity you'll actually need. Estimate the average and "typical" miles/day you put on your existing cars, and estimate how many hours of "down-time" (typically evenings & overnight) each car will have. That's your starting point -- the range replenishment that you need.

My main panel couldn't be expanded without some significant re-wiring. However, the 10 mile/hour replenishment rate supported by an existing 240V, 20A circuit was sufficient to keep the car fully charged on average -- occasional incomplete charges were offset by full charges the next night.
 
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They will likely run the sub-panel anyway, as you will need a switch in the garage to be able to shut it off locally.
I read quickly that is required in MD so prob here in VA too.

It will need to be tied into the main panel unless you have a separate meter installed.
Ah ok. I just wasn't sure how it would be connected. Makes sense.

Zeroeth, make an estimate of how much charge capacity you'll actually need. Estimate the average and "typical" miles/day you put on your existing cars, and estimate how many hours of "down-time" (typically evenings & overnight) each car will have. That's your starting point -- the range replenishment that you need.

My main panel couldn't be expanded without some significant re-wiring. However, the 10 mile/hour replenishment rate supported by an existing 240V, 20A circuit was sufficient to keep the car fully charged on average -- occasional incomplete charges were offset by full charges the next night.

I could do that or just invest a couple $k into this upfront and not have to worry about it again... The wife and I are already busy enough that I just don't want to have to think about charging time. A simple rule that when the car is in the garage, PLUG IT IN will be the only step outside of obvious things.

I think these people have not caught on that you will have two Teslas, and likely no ICE car for backup. Do it right. If you are that committed to going electric, build the infrastructure to make it work without any inconvenience.

Yea. I definitely want to do this right up front. Also... getting this done will be required inevitably anyway with the way technology has engulfed the auto industry. I have an ICE Wrangler as our backup vehicle but I just hate driving that thing down the highway on a windy day... It's a mental workout.. lol. and a gas hog as well.
 
You will also need to think about the service coming into the house, that will likely need to be upgraded (new lines from the pole) if you only have 150 amp service now.

The key here is you want to be able to pull 80 amps just for the cars, thats over 50% of your load on your main breaker. It's possible, but only if you don't have alot of other large loads like electric range, dryer, AC, etc...
 
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Really depends on how you want to set it up. My utility requires a separate meter (one line from the pole to two meters) if you want to take advantage of the lower overnight rates. This separate meter is running to a dedicated breaker box.

If you need to upgrade your power from the pole, I would consider doing a separate panel right off the meter. May be cheaper in the long run. Does your utility offer a program for EV charging?
 

BerTX

Active Member
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May 2, 2014
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Texas/Washington
You will also need to think about the service coming into the house, that will likely need to be upgraded (new lines from the pole) if you only have 150 amp service now.

The key here is you want to be able to pull 80 amps just for the cars, thats over 50% of your load on your main breaker. It's possible, but only if you don't have alot of other large loads like electric range, dryer, AC, etc...

Definitely something to check. The power company generally WAY oversizes the drop, but an older home may be an issue.
 
In most cases, depending on other home electrical draws like do you have a gas or electric stove/dryer/etc..., 150A won't be enough when using up to 100A of that service for the charging of electric cars/anything. You'll likely need a minimum of 200A service to accommodate all of your loads but I'm not a licensed electrician, just an amateur one... LOL

Service upgrades can be quite pricy depending on a number of factors like above/under ground service lines, transformer capabilities upstream, etc...

Jeff
 

Branzo90D

Salt and Pepper
Oct 13, 2015
154
101
NorCal
First, look in you laundry room. Do you have an unused dryer plug , or plumbing for a gas dryer? It might be a lot simpler to buy a gas dryer and move the dryer plug. Unless you and your spouse both have a long commute, a 110 plug might even be workable on one of two electric cars. Remember, you don't start every day with a full tank in a gasoline car.

That's exactly what I did. I have only 100 amp service in my home. As others have stated, you don't need 100A of electrical service just to charge your car. The rating is for continuous use for all needs in the home when used simultaneously.

I use the UMC that came with the car to charge through a NEMA 14-50 plug mounted in the garage using the old dryer plug circuit. This charges the car at 240V/40A and it is plenty of charging speed for my needs. I turn on the charging at 11 PM (electricity cost rates are lower at night in many places) and the car is usually charged to 80% within a couple of hours. Even when I come home with 20% SoC, I can charge it to 80% by about 4 or 5 AM while rates are still low.

If you plan to have two electric vehicles at the same time, you may want to put in a solution now which will better suit your future needs, however.
 
Your electric company can tell you the capacity of their lines to your service entrance. If they need to be upgraded, they will likely have to end someone out to survey before they can tell you how much it would cost (if anything).

At my house, I have a 100A panel and incoming underground service capable of only 125A. Very expensive to upgrade.

Do you have 240V breakers that are not in use; stove, oven, dryer? I have a gas dryer so I was able to move the 30A dryer outlet to a convenient spot for charging. to add 80% (56kWh) overnight on my S70 takes 10 hours.
 
Your electric company can tell you the capacity of their lines to your service entrance. If they need to be upgraded, they will likely have to end someone out to survey before they can tell you how much it would cost (if anything).

At my house, I have a 100A panel and incoming underground service capable of only 125A. Very expensive to upgrade.

Do you have 240V breakers that are not in use; stove, oven, dryer? I have a gas dryer so I was able to move the 30A dryer outlet to a convenient spot for charging. to add 80% (56kWh) overnight on my S70 takes 10 hours.
I'll have to take a look at the breakers again when I get home. This is our first house so I'm still getting used to the amount of breakers we now have.

My electrician is coming out anyway to troubleshoot our wood stove insert blower (installer shorted out a bunch of wires due to negligence). I had already ran it by him a couple weeks ago, and showed him the path from the breakerbox in the basement to the garage that he could take. I already have holes in the walls in the basement for when I ran a fiber cable from outside the house to a utility room in the basement for my internet. There's enough already done to get him 80% the way to the garage.

If upgrading the service to the house ends up costing over $5k, I might just have him run the required wiring for a 100A subpanel in the garage, but install a smaller set of breakers or something like that until we get our second EV 2 years from now.
 
Lots of good advice above. Keep in mind that two Tesla Wall Chargers will work together to use whatever power is available. 220v 50amp will give you about 30 range miles per hour. That is roughly a max of 300 miles per 10 hrs.

My daily commute can range between 80-120 miles round trip for 2 locations I go to frequently. My wife has a 60 mile round trip commute. We will benefit from a dedicated 100A circuit for daily charging.

When charging starts the two chargers will use max current, but as the cars "fill up" they use less power, so both cars can be charging at "full speed" after a few hours. I believe you will be fine with 2 HPWC and a 50 amp circuit. This may be worth considering if you have a 50 amp circuit available. If you need to upgrade your service then go all the way with 100 amps.
 
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Lots of good advice above. Keep in mind that two Tesla Wall Chargers will work together to use whatever power is available. 220v 50amp will give you about 30 range miles per hour. That is roughly a max of 300 miles per 10 hrs.

Hmmm... That's interesting. On a bad day driving separately, we should be commuting a combined total of 180 miles. At 40A - 30miles/hour charging rate, it should only take between 6-8 hours of charging total.

Just trying to get in a different mindset of travel logistics.... lol. If my wife drives to work on Friday with a 100% charge and comes home. Then we pack up for a small roadtrip to visit family. I could at least recoup half of the miles she used going to work and back in about an hour of charging at home while we pack. I could still have enough left in the battery to drive the 180 miles to the supercharger in the family's city with a little room to spare. It would be close, but about 1/3 of that trip is 55mph.

I'll have to have the electrician look the panel over on Monday to see if we can free up something. I could make do with a 50A circuit for now. Plus to be honest, we carpool in her SUV about 50% of the time anyway. Our work schedule is far from static....
 

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