Charger Installation Q

[Jonathan S.]

Our home charger installation was relatively simple since we have a 200a panel.
(Snaking the line from the panel in the basement ski workshop to the garage was another matter! Fortunately the quote in advance was fixed-fee, since it took two person-days, one of which was two electricians playing Marco Polo for half a day ... and in brutally hot weather.)

I'm looking at a house to serve as the northern satellite base for my ski mountaineering habit.
(West Side of Mt Washington NH.)
Won't get used on an extended basis until our daughter is off at college, and she's only in eighth grade.
But tempting to buy now!

Details:

• Panel is only 100a. (Seems a big meager for 1987 construction w/ 2400 sq ft?)
• Panel location is in walk-out basement. (So easy access to exterior.)
• Garage is detached. (Why would anyone design this?)
• Distance from panel to corner of house is ~12' (based on floor plan), then an underground line runs to the corner of the garage for ~24' (based on aerial view).
• Garage probably does not have a subpanel (but not 100% on that).

So ... what exactly would need to be done?
(Assumed a hard-wired "universal" charger from the company run by you-know-who.)

TIA!

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[daveo4EV]

easy peasy - since it's a vacation home I'd just install any "good" EVSE and run a 40/50/60 amp breaker/circuit to the new EVSE

the real issue is local building codes for "adding" a new 240V circuit - based on current usage/capacity of the main panel

then pulling the new wire - since it's a new wire pull I'd go with NEMA 6-50 _OR_ hardwired - in each case you'll save some money on the wire by only pulling 3 wires instead of 4 wire - the 4th wire is unused by EVSE's.

the real issue to get answered is how big a circuit can "fit" into the existing home's panel - and then the 2nd issue is the actual wire pull - after that it's easy peasy

I'd get a licenced/bonded local electrician who can advise you and then get anywhere from a 30-60 amp circuit based on what's allowed - once you know your circuit size you can purchase any number of EVSE's to match the breaker/circuit size.

 

[Jonathan S.]

I knew you'd be the one to chime in first.
(Thanks!)

For how big a circuit can fit into the existing home panel, I was thinking that at 100a, it has almost no excess capacity?
If so, then does that mean I have the options of either replacing the current in-house panel w/ an entirely new 200a panel *or* adding a 100a subpanel to the garage?
(Local building codes? This is New Hampshire, with the state motto of Live Free or Die! Just kidding, I will of course find the most reputable local electrician and not skimp on anything, but I do want to have an overview of my options ahead of time.)

I'm also wondering if a 100a panel means that the service entrance write to the house from the pole/transformer needs to be upgraded?

 

[RAHRCR]

I have a 200A panel and added a 100A subpanel ~100ft away to my attached garage. From there I have a 60A circuit to service my EVSE. Not cheap but it enables all kinds of things that I want to do in the garage

 

[daveo4EV]

I knew you'd be the one to chime in first.
(Thanks!)

For how big a circuit can fit into the existing home panel, I was thinking that at 100a, it has almost no excess capacity?
If so, then does that mean I have the options of either replacing the current in-house panel w/ an entirely new 200a panel *or* adding a 100a subpanel to the garage?
(Local building codes? This is New Hampshire, with the state motto of Live Free or Die! Just kidding, I will of course find the most reputable local electrician and not skimp on anything, but I do want to have an overview of my options ahead of time.)

I'm also wondering if a 100a panel means that the service entrance write to the house from the pole/transformer needs to be upgraded?

in california the max circuit you can "add" is based on a ratio of existing 240v circuits to main breaker size - you may also be able to move to 125/150 amp main breaker with out a new panel, but that all depends on your panel type/age and local building codes…

upgrading to 200 amp main service may not be that expensive - or just run a dedicated 100 amp service to the garage - pole based service changes/additions are sometimes easier and more affordable than under ground service

the real problem here is your options are "unique" to your building and local building codes and your existing set of breakers - so there is no "fixed ansnwer" - the only correct answer is "it depends" - and no one on this forum is likely to be qualified to answer "what can I do" unless they happen to be a licenced electrician in New Hampshire…

so the only answer is: I don't know - it depends.

there are always options for different levels of cost.

 

[Jonathan S.]

Okay, thanks, that sounds like enough info to move forward, with the likely outcome that the EVSE install would be far more expensive than it was at my primary residence, but not a dealbreaker, for either EVSE or the house purchase.
Now I can go back to worrying about whether the nearby snowmobile trail would be too noisy!
I think the only way to assess that will be to take a house "tour" that entails just sitting in various parts of the house while working on my laptop for an hour or so.
(During one big snow year here in western Mass, when snowmobiles were traveling on the bike path near my house, the sound was annoying in the sense that they were violating the prohibition on motorized use, but the sound was not annoying in and of itself.)

 

[snstevens]

Here is an alternative -- Check with the local utility and tell them you want to add an EV charger in your garage, but that it is a stand-alone structure, and the panel in your home doesn't support an additional 100A (or 80A, 60A or 50A - whatever) breaker. Ask whether the utility would drop a new power line to the garage with a second meter.

My friend in Seattle did this same thing. Although the Utility generally doesn't allow 2 meters for a single customer on a property, they made an exception because he was using it to charge an EV, and they are trying to encourage that.

Good luck!

 

[Jonathan S.]

Ooh, I like that idea, thanks!

Turns out I'll be able to get an in-depth look at the house, since it's currently being used as an Airbnb rental. (Perfect reviews, except for the occasional problem with the rental agency.)

I've booked a family weekend trip for March 8-10, which will probably be preceded at some point by a booking with my ski mountaineering partners (thereby guaranteeing sideways freezing rain during that period).

My wife though is already favoring buying a condo instead right at the resort, rather than the ~8 min drive from this freestanding house.
Unfortunately, that would mean no garage (as the only properties right at the resort with a garage are far too big for any conceivable use by us, even far bigger than our primary residence, which is kind of excessive anyways).
Which in turn would mean, sigh, no Taycan trips there, as the entire charging infrastructure at the mega-large downhill ski area, big nordic touring center (and major golf course during the summer), massive old grand hotel, new conference center, and extensive condo developments, comprises ...
... two 14-50 outlets:
https://www.plugshare.com/location/40089

 

[WasserGKuehlt]

Which in turn would mean, sigh, no Taycan trips there, as the entire charging infrastructure at the mega-large downhill ski area, big nordic touring center (and major golf course during the summer), massive old grand hotel, new conference center, and extensive condo developments, comprises ...
... two 14-50 outlets:
https://www.plugshare.com/location/40089

I mean, who would ski there, amirite? <ducks, runs>

Look, the location has a solid 10.0 score. <ducks again>

Seriously, though, all you'd need at the condo is just a 14-50 plug with a locked enclosure.

 

[Jonathan S.]

Unfortunately, I’m pretty sure these condos don’t allow any external modifications like that.
But given that none of them are on the market now, I can worry about that at some point in the future … and by then, perhaps one of the biggest resort complexes in northern New England will even have EV charging!

 

[Jonathan S.]

I just realized that I might have a far easier solution, as the laundry room window is adjacent to both the driveway and the detached garage.

So if the laundry room has a dryer outlet (which it must, unless the dryer is on the house's propane supply and an outlet was never installed for an electric dryer, which seems almost impossible):

• For my Feb 4-6 rental, unplug clothes dryer, plug in Porsche EVSE via one of my many adapters and my extension cord (note to self: remember to transfer all that from my Taycan frunk into my A6ar I'll be driving on this trip, plus some insulation to seal up the gap in the slightly ajar laundry room window), and plug in my ski mountaineer partner's Prius PHEV (which makes for the perfect experiment, since seeking out an alternative is unnecessary should this not work), with no need to adjust the setting on the Porsche EVSE given that his Prius PHEV 3.3 kW charging speed is so slow that any dryer outlet can handle the power draw. (In case you're wondering how one of my ski mountaineering partners could drive a Prius PHEV, he lives in Richmond VA. And in case you're wondering why/how he lives down there, he's originally from there, but went to Dartmouth, and has always really been into the White Mountains, so now that he's retired, he's taking more trips up north.)
• For my Mar 8-10 rental, same routine, except use my wife's i4 EVSE (but remember to pack adapter, extension cord, and insulation into my A6ar), and lower the amp setting on the BMW app once she arrives separately with our daughter and friends.
• Should I decide to buy the house, for a permanent setup, dependent of course on the exact NEMA receptacle type (probably 10-30, since house was built in 1987), plug this: https://splitvolt.com/collections/all/products/splitvolt-safety-certified-splitter-switch-nema-10-30 ... into the dryer outlet, then run this: https://splitvolt.com/collections/all/products/egb-nema-10-30?variant=40778620797068 ... from that splitter switch out to the detached garage, and finally plug this: https://splitvolt.com/collections/all/products/cgb-nema-10-30-24-amp?variant=40763975499916 ... into the extension cord, mount on a garage wall, and I'm all set!

(Right? Far slower than our hardwired 48amp EVSE at our primary residence, but will be fine for up there.)

 

[daveo4EV]

I just realized that I might have a far easier solution, as the laundry room window is adjacent to both the driveway and the detached garage.

So if the laundry room has a dryer outlet (which it must, unless the dryer is on the house's propane supply and an outlet was never installed for an electric dryer, which seems almost impossible):

• For my Feb 4-6 rental, unplug clothes dryer, plug in Porsche EVSE via one of my many adapters and my extension cord (note to self: remember to transfer all that from my Taycan frunk into my A6ar I'll be driving on this trip, plus some insulation to seal up the gap in the slightly ajar laundry room window), and plug in my ski mountaineer partner's Prius PHEV (which makes for the perfect experiment, since seeking out an alternative is unnecessary should this not work), with no need to adjust the setting on the Porsche EVSE given that his Prius PHEV 3.3 kW charging speed is so slow that any dryer outlet can handle the power draw. (In case you're wondering how one of my ski mountaineering partners could drive a Prius PHEV, he lives in Richmond VA. And in case you're wondering why/how he lives down there, he's originally from there, but went to Dartmouth, and has always really been into the White Mountains, so now that he's retired, he's taking more trips up north.)
• For my Mar 8-10 rental, same routine, except use my wife's i4 EVSE (but remember to pack adapter, extension cord, and insulation into my A6ar), and lower the amp setting on the BMW app once she arrives separately with our daughter and friends.
• Should I decide to buy the house, for a permanent setup, dependent of course on the exact NEMA receptacle type (probably 10-30, since house was built in 1987), plug this: https://splitvolt.com/collections/all/products/splitvolt-safety-certified-splitter-switch-nema-10-30 ... into the dryer outlet, then run this: https://splitvolt.com/collections/all/products/egb-nema-10-30?variant=40778620797068 ... from that splitter switch out to the detached garage, and finally plug this: https://splitvolt.com/collections/all/products/cgb-nema-10-30-24-amp?variant=40763975499916 ... into the extension cord, mount on a garage wall, and I'm all set!

(Right? Far slower than our hardwired 48amp EVSE at our primary residence, but will be fine for up there.)

good and functional plan…longer term you can eventually decide what to do if anything differently.

just make sure you have a NEMA 10-30 and 14-30 supply cable and adatper - I'd bring one actual NEMA 10-30 cable and a 14-30 to 10-30 adapter - that way it won't matter which type of NEMA plug it has.

 

[Jonathan S.]

Thanks for the feedback!
I think I should be all set with my existing kit for my Feb & Mar rental trips, since I can plug one of these:

https://www.amazon.com/gp/product/B09TB814K8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1​

https://www.amazon.com/gp/product/B08GC8KNJQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1​

... into the dryer outlet, then this:

https://www.amazon.com/gp/product/B0BS3TZB42/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1​

... goes into that adapter, and finally either the Porsche or BMW EVSE goes into the extension cord.

(Note that despite driving something like 15,000 miles between our two cars with that kit, I've used it exactly zero times, as the only time we've used either the Porsche or BMW EVSE has been for L1.)

 

[daveo4EV]

Thanks for the feedback!
I think I should be all set with my existing kit for my Feb & Mar rental trips, since I can plug one of these:

https://www.amazon.com/gp/product/B09TB814K8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1​

https://www.amazon.com/gp/product/B08GC8KNJQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1​

... into the dryer outlet, then this:

https://www.amazon.com/gp/product/B0BS3TZB42/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1​

... goes into that adapter, and finally either the Porsche or BMW EVSE goes into the extension cord.

(Note that despite driving something like 15,000 miles between our two cars with that kit, I've used it exactly zero times, as the only time we've used either the Porsche or BMW EVSE has been for L1.)

only thing to be careful about is you need to adjust the EV charger (EVSE) to charge at 24 amps (or less) - if you're using an adapter the EVSE may not realized it's on a 30 amp circuit and will attempt to pull the full 40 amps

it's best to use a vendor provided powersupply adapter - because in the case of Porsche's EVSE when you swap the power suppy cable it also "adjusts/informs/configures" the EVSE to match the breaker size of the associated power supply cable - this adjustment does not happen if you're using a simple generic NEMA plug adapter…but still have NEMA 14-50 supplly cable attached to the EVSE.

for a dryer plug (NEMA 10-30/14-30) the breaker size (and associated wire gauge) is rated for 30 amps - and with an EVSE you need to adjust that to 80% of breaker size - which is 24 amps - or about 5.76 kW

adapters like the one you are talking about are _NO_ problem functionality but you need to make sure to downrate the EVSE to match the circuit's capacity.

other than that you're good to go.

 

[Jonathan S.]

Definitely a good idea not to melt down an outlet in a rented house!

For my wife's i4 and BMW EVSE, that should be easy, since the app has a slider switch, which I can set at 20a. (No option for 24a, as it goes from Unlimited/48 to 32 to 20 to 16 and then in 1a increments down to 6.)

For my friend's Prius PHEV, do I need to set my Porsche EVSE for him at the 50% setting, or is that moot since his Prius PHEV can't draw more than 3.3kW? (I'll confirm that he has a pre-2023 that maxes out at 3.3kW. I'll also check if he has his own mobile EVSE -- I know that he has a dedicated EVSE at his house.)

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