The slippery slope of electrical upgrades - or help I'm still charging at 120V!

[timeshifter]

Thinking once again about upgrading my electrical service to better support charging my car at home.

Background: bought my first EV, a Standard Range Model Y about two and a half years ago. During the purchase process and as soon as I got it home I was planning on upgrading the circuit to my garage. I even snickered at a guy I know who'd had a Model 3 for several years and was still charging at 120V 15A. Well, I'm now that guy.

I ended up staying at 120V 15A because getting a bigger circuit to the garage became a slippery slope. One electrician I trust thought I could add on at least a 240V 30A circuit. Another felt that my panel was too full. My service is 100A. So I decided to stay put as I didn't want to take on the expense of a full panel upgrade and I didn't want a half-assed circuit to the garage.

I've always been interested in upgrading my main service above the 100A, just never found the time or the money or the will to do it. However, recently I've done some more long drives during the day and am regretting that I can't charge faster.

Anyway, I'm trying to get a handle on the big picture of what I should do in terms on main service to the house and how much amperage to the garage.

My house is a 30 year old 2000 sq ft ranch with a full sized, unfinished basement, and an attached two car garage. We're new empty nesters, having sent our son off to college recently. My wife's car is not an EV, but I suspect she'll have one down the road. I have no plans to move and expect all my cars will be EVs from here on out.

So, how big of a main service should I upgrade to? 200, 300, 400? How much juice should I push to the garage, which is about 50 feet away from the panel? Should I put a sub panel in the garage?

 

[bruce4000]

If you have been getting by with a 100 amp panel then I would go with the standard 200 amp panel. I was living with charging on 120V / 20 amp circuit but recently upgraded to the Tesla Wall Charger. I had room on my 200 amp panel for a 50 amp 240V breaker but unless you have a long commute or drive for Uber, I think 240V / 40 amp breaker is plenty. With my Model YLR , at 31 amps, I get 10% an hour so can do 80% in 8 hours overnight.

 

[Cosmacelf]

Can you give us a picture of your current panel showing the breakers?

If doing a panel upgrade, such a house will not need more than a 200A service. If you think you’ll be charging two EVs in the future, then putting a 100A subpanel in the garage makes sense.

 

[timeshifter]

 

[timeshifter]

I found my notes about what the one electrician said. He thought my panel was over the limit. It's been two years, but in my notes I wrote "4 too many doubles" and "2 too many quads" and "4 wires on bus over limit".

 

[dafish]

1. Have you investigated the utility costs to upgrade? Both 200 and 400?
2. Have you evaluated putting in a new service just to the garage?
3. What do you expect future technologies will allow for DC charging per EV.

If I was upgrading an overloaded panel and planning to support two EV’s I would not be thinking another 100 amps. YMMV

 

[timeshifter]

1. Have you investigated the utility costs to upgrade? Both 200 and 400?
2. Have you evaluated putting in a new service just to the garage?
3. What do you expect future technologies will allow for EC charging per EV.

If I was upgrading an overloaded panel and planning to support two EV’s I would not be thinking another 100 amps. YMMV

1. I haven't looked into this seriously since I got my car about two years ago. I do recall one electrician indicating that a 400 amp service would be a whole magnitude higher than 200. Didn't make sense to me why then or now. Not everyone told me that but at least one did.
2. Hadn't really considered that. I'd really like to do a whole house upgrade regardless.
3. I don't know what "EC charging per EV" means. I presume that is a charge system that can alternate between cars.

I'm also thinking more than another 100 amps, don't think I'd regret over building it, but would like to have some justification or reasoning why more that 100 is a good idea.

 

[dafish]

Typo. Read DC charging…. I’ll correct.

 

[E90alex]

200A service would be more than enough if you’re already getting by with 100A for your house. The only reason you can’t add a circuit now is because your panel is full, not necessarily because 100A service isn’t enough to charge an EV.

A 240V charger would be exponentially faster than 120V@15A so the electrical load to charge the car can be confined to night time when you don’t have other major appliances running. Figure for a Model 3/Y charging at 240V 32-40A it’s approximately +/- 1 hour of charging per 10% of battery.

Running 100A to a garage sub panel would be more than enough to future proof and support two EVSEs. Keep in mind depending on your EVSE setup you can always load share between two of them and/or schedule it so one car charges first then the other instead of charging both at full power concurrently.

 

[stopcrazypp]

Thinking once again about upgrading my electrical service to better support charging my car at home.

Background: bought my first EV, a Standard Range Model Y about two and a half years ago. During the purchase process and as soon as I got it home I was planning on upgrading the circuit to my garage. I even snickered at a guy I know who'd had a Model 3 for several years and was still charging at 120V 15A. Well, I'm now that guy.

I ended up staying at 120V 15A because getting a bigger circuit to the garage became a slippery slope. One electrician I trust thought I could add on at least a 240V 30A circuit. Another felt that my panel was too full. My service is 100A. So I decided to stay put as I didn't want to take on the expense of a full panel upgrade and I didn't want a half-assed circuit to the garage.

I know you consider it "half-assed" but even changing it to a 240V 15A circuit can mean major charging speed increases. 120V 15A means a huge amount of power is lost to overhead, especially in extreme weather where heating may be required.

Have you seriously considered the other options including the intermediate ones? Here's the mph charging speeds for Model Y for the other adapters.

5-15	3 mi
5-20	4 mi
6-15	10 mi
6-20	14 mi
10-30	21 mi
14-30	21 mi
14-50	29 mi
6-50	29 mi

https://shop.tesla.com/product/gen-2-nema-adapters

If your dryer outlet is easily accessible and you don't need use it while you are charging, you can even consider a NeoCharge splitter (UL listed), which allows you use your existing setup to set up 14-30 charging.
Amazon.com

I've always been interested in upgrading my main service above the 100A, just never found the time or the money or the will to do it. However, recently I've done some more long drives during the day and am regretting that I can't charge faster.

Anyway, I'm trying to get a handle on the big picture of what I should do in terms on main service to the house and how much amperage to the garage.

My house is a 30 year old 2000 sq ft ranch with a full sized, unfinished basement, and an attached two car garage. We're new empty nesters, having sent our son off to college recently. My wife's car is not an EV, but I suspect she'll have one down the road. I have no plans to move and expect all my cars will be EVs from here on out.

So, how big of a main service should I upgrade to? 200, 300, 400? How much juice should I push to the garage, which is about 50 feet away from the panel? Should I put a sub panel in the garage?

As others mentioned, if all your other loads can get by with 100A, 200A seems like the next logical move (assuming you feel the options I mentioned above don't make sense). 400A is a whole other ball game and probably not worth it, and many power companies do not offer intermediate options like 300A (not that you really need it).

 

[timeshifter]

Have you seriously considered the other options including the intermediate ones? Here's the mph charging speeds for Model Y for the other adapters.

I have considered those in the past. Anything above what I'm getting now would require the labor of running new wiring from the panel to the garage. So if I'm going to have to pay for the labor I may as well pay for a thicker wire while I'm at it.

 

[boulder.dude]

We added a new panel “in front of” the existing main panel. So the new psnel became the main panel and the existing panel became a sub panel. Then we ran a 60A circuit to the garage from the new main panel.

 

[SalisburySam]

To @timeshifter I too would recommend an upgrade to 200amp service for your existing home. This would likely include either a much larger or second load center (circuit breaker panel) giving you the opportunity to get rid of the questionable number of dual- and quad-breakers, number of wires, etc. Most of what you might buy inside the home in the future could actually reduce consumption given ever-increasing efficiencies of lighting, HVAC systems, electric hot water systems, washers/dryers, induction cooktops, even ovens, pool pumps, irrigation pumps, etc. Any consumption increase will probably result from adding new electrical stuff, perhaps not envisioned today beyond multiple EVs.

As for the larger option of 400amps, some considerations here. We did just that about a decade ago when we moved into our 1905-built historic home with woefully undersized electrical capacity. For us it involved lots of moving parts:

• Running (MUCH) larger wires from the power pole transformer to the service meter (our cost).
• A new meter (our cost).
• A new 400amp load center plus a split from it to two 200amp load centers for further distribution to the home (our cost).
• A new trench, conduit, and 100amp load center for the detached garage (our cost).
• A new transformer on the power pole (utility cost, thankfully).

The upside to all of this is that we feel this home now has sufficient power for anything we could throw at it and is a nice selling feature for when that time comes as it eventually will. One fun example: in her initial discussion to replace our ancient HVAC unit with a two new high efficiency units, the sales person asked if we thought we had sufficient power for the replacements. We laughed.

By the way, in addition to the costs for the items above there is an another consideration to 400amp service. If you plan to get a whole house standby generator in the future you will likely have to get two 200-amp transfer switches as to date I’ve not seen a 400amp one, making this install more complex, more expensive, and taking up a lot more wall space.

Good luck with your decision, and share with us what that is and how it works out for you.

 

[legendsk]

We added a new panel “in front of” the existing main panel. So the new psnel became the main panel and the existing panel became a sub panel. Then we ran a 60A circuit to the garage from the new main panel.

I added a 34' wide garage onto the end of my 40 year old house. The original house had 100A power dropped from a pole to the house. I buried the line from the pole to the house, then put a new 200A main panel in the new garage, (with lots of outlets, including a couple of 14-50R ), and simply fed the original 100A panel as a sub panel from the new 200A. I didn't really break out the electrical cost separately, but it was a small part of the whole project. Basically the reverse of your solution, but equally effective. I imagine the total electrical part was $2,500 or thereabouts, mostly for heavy duty copper wire.

 

[Cosmacelf]

Incidentally, there are costs associated with staying at 120v/15A. Due to various inefficiencies, you pay more over the course of a year.

The calculator at the bottom of this page calculates it for you: CarCharging.us

Given that panel, I would definitely upgrade service to 200A.

 

[NickFie]

Even if you’re not ready to spring for 200 Amp service, at least get future-ready to the extent your budget allows.

- Consult one or two recommended electricians for estimates on the best option for a 200 Amp panel. Total replacement or twin panels.

- Also get estimates to run a 100 Amp capacity COPPER line to a sub-panel in your garage. Safer for you, one potential home sale stumbling block eliminated. “Is there ANY aluminum wiring in this residence?”

- Get your electric utility’s estimate for either additional 100 Amp service to your garage (suboptimal) or upgrade to 200 Amp service for your house (optimum). If the second 100 Amp service costs far less, you could use it for time-of-day service for EV charging and possibly some home appliances such as the dryer.

If you’re scraping the bottom of your budget, install the 100 Amp garage line & subpanel.

…Attach to 240-volt, 20 Amp breaker.

…Install Tesla HPWC (or equivalent) in garage wired to the subpanel with either 100 Amp cable ( probably Number 2 Copper, best) or 60 Amp capable cable (probably Number 6 Copper).

…Install 20-Amp 240 Volt breaker in the subpanel for the HPWC connection.

…Configure HPWC for 20 Amp circuit during setup.

This provides more than 125% faster charging than a wall plug.
- 2x voltage. Possibly higher thanks to larger gauge cabling.
- 1.25x Amps
- Improved on-board charge efficiency means higher percentage of the power makes it into the battery cells.

If you can afford it, it’s best to get all the work done at the same time.
- Ongoing inflation will jack up material and labor costs.
- Repeat estimates and visits add cost.
- Later-stage work will inevitably involve removing/replacing items paid for in earlier stages.
- Minimal accountability. Any errors discovered in Step N+1 will be attributed to Step N or earlier.

If possible, get all the residential 200 Amp work done in one project. Then there’s minimal internal electrical work after the utility upgrade.

 

[Big Dog]

we have a 100 amp panel and our electrician was able to add a sub-panel for the Tesla wall charger. I don't know the technical issues involved, but it was a whole lot cheaper than upgrading to a 200 amp panel. (Figured I'd save the upgrade for the day we added solar panels.). You might ask if a sub-panel is possible in your situation.

 

[CaseyL]

As for the larger option of 400amps, some considerations here. We did just that about a decade ago when we moved into our 1905-built historic home with woefully undersized electrical capacity. For us it involved lots of moving parts:

• Running (MUCH) larger wires from the power pole transformer to the service meter (our cost).
• A new meter (our cost).
• A new 400amp load center plus a split from it to two 200amp load centers for further distribution to the home (our cost).
• A new trench, conduit, and 100amp load center for the detached garage (our cost).
• A new transformer on the power pole (utility cost, thankfully).

This is an interesting option. Did your cost per kWh change at all because of the 400 amp service?

 

[Unclepaul]

Your home will be much happier with 200 amp service. You will too

 

[timeshifter]

Your home will be much happier with 200 amp service. You will too

Yep. 200 amp is pretty much my baseline at this point. Only remaining thoughts are whether I should go above 200 and what should I run to the garage.