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Wall Connector Install - 50 v 40 amp

My wife and I determined that for our particular needs we’d go ahead and order the wall connector. We have a family friend finishing his electrician journeyman work (he’s in the third year of apprenticeship), so we’re more than happy to give him hours.

Our home has 125amp service with a 60amp sub panel in the garage (we’re a little under 2,000 sq ft with all major energy hog appliances running on natural gas except the AC). With the current setup of our sub panel, and what’s used on the main, we can either install a 40amp or 50amp breaker for the wall charger.

Will the 40amp vs 50amp breaker make that much of a difference for day-to-day charging (assuming we probably aren’t draining more than 80 miles of a range on an average day)? I know the numbers Tesla claims but we’re interested in real-world experience. Our load calculations show we shouldn’t have issues with a 50amp given the only other breaker on the side of the garage subpanel we plan to use is the garage door opener (one car garage). But, our garage is unfinished (exposed studs) so we’re considering a 40amp to put less stress on the wiring during large temperature fluctuations.

Also does anyone have experience with (particularly NJ) declaring self installs? We can’t use our friend’s credentials because he’s still apprenticing, so I imagine as a “homeowner install” the inspector will apply more scrutiny. Anything I should be prepared to answer outside of basic questions (ie: we used 6 awg wire, this Is a 60 amp panel, car won’t draw more than “X” amps at x V per the programmed commissioning, etc)? I could also just ask our friend to come for the inspection and pose as me.

Thanks in advance!
 
Go bigger vs smaller. If you put in a 50A breaker and have the dedicated wall charger that can actually use it (well, 40A of it since it only uses 80%), you can charge 35-40 miles per hour. If you're finding you trip your breaker often, just limit the amount of current your car draws until a happy level. Then if you ever NEED a fast charge, you can just crank it back up and make sure not to use other high energy devices during that time.

Also, a 40A 240V vs 50A 240V breaker is the same price. Moving from 6ga to 4ga wire will cost you a little more though.

Last thing, I ran 4ga wire with a 60A for my Gen 2 Mobile Connector. I did it in the event that I want to upgrade to a wall charger at some point that uses a 60A service, outputs 48A (max load the on-car inverter can handle), and about 44 miles of range per hour.
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
6,845
13,402
Springfield, VA
What else is on that 60 amp sub panel?

Unless you have time-of-use rates or find yourself needing to add a lot of range in a short period of time, you'll probably find a 40 amp breaker (providing 32 amp charging) will be more than sufficient. At 32 amps, a full charge 0-100% will take about 10 hours.

Also keep in mind that NJ is pretty saturated with Superchargers, so you should have plenty of fast options if you find yourself needing to turn-and-burn without enough time to charge at home.
 
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RandyS

Fan of Elon
Jul 8, 2012
802
1,059
San Diego
Respectfully, I think you're starting at the end and working backwards (50 vs. 40 amp connection). Have your electrician friend perform a load calculation to see how much capacity you have in your panel for a new circuit and go from there. Not knowing the particulars, you may not have enough capacity for either a 40 amp or a 50 amp circuit...You may only be able to install a 20 or 30 amp circuit, given your panel. But you won't really know until you or your friend perform a load calculation...And, of course, besides the load calculation that will tell you how much capacity you have, you'll also need physical space to install a new double-pole breaker for the new charging circuit...
 

jcanoe

Well-Known Member
Oct 2, 2020
5,285
5,757
Maryland
If your home has the additional capacity then installing either the 40A or 50A circuit should be adequate for daily charging at home.

The main benefits of the Wall Connector include:

Fully sealed for use in all weather conditions (not as important since the Wall Connector will be installed inside a garage.)

Requires only 2 wires (plus ground wire) instead of 3 wires (plus ground) so the cost of the wire will lower, pulling the wire easier.

Installation of a Wall Connector at your property may qualify for a federal tax credit (see IRS publication 8911, consult with your tax advisor.)

Load sharing (future capabilty, enabling two Wall Connectors to be installed on the same circuit)

Possible limitation: The charging cord of the Tesla Gen3 Wall Connector is only ~18 feet long (same as the Mobile Connector.) Measure to be certain that the charging cord will be able to reach the Tesla's charging port (located at the left rear corner of the Tesla vehicle) from the planned location of the Wall Connector.
 
What else is on that 60 amp sub panel?
It’s a little bit of a mess. The previous homeowner had all sorts of “toys” hardwired in that he took with him when we bought the house a year ago (he used the garage as a workshop). This panel looks full but when we do the charger we’re taking out everything that’s currently switched to off (2,4,6,9,10). They’re all breakers without wiring so not loosing anything. I imagine he‘ll use 2,4 for the double pole 50 or 40 breaker. He also mentioned that the garage door doesn’t need to be on a 20amp.

A19DDF6C-3A9A-4199-B8B4-ED63EF810BF5.jpeg

We have the option of signing up for time of use. We haven’t given we’re working at home until the end of the pandemic. We’re in central NJ so there are plenty of super chargers and L2s around, just more convenient and cheaper to do at home (minus the upfront cost of material of course!)
 
Personally, with only a 125A supply I would only do 30A. I rarely charge over 10-12A myself, as the car is almost always parked long enough to add the range I need, and I can use more of my own solar this way. If you were to charge at 40A, you would likely see pretty significant voltage drop, especially if you are running your air conditioning— that is just wasted energy.
 

rjpjnk

Active Member
Mar 12, 2021
1,211
786
NJ
If the rest of the circuits in your sub panel are properly protected with appropriate circuit breakers (including the main feed to the panel) there is nothing to worry about. Since you have already run 6 gauge wire I would install a 50 (or even 60) amp breaker. The wall charger is capable of drawing many different current levels by configuration. Try the highest setting and if the main sub panel breaker trips once in a while (when you are using other stuff) reduce the setting in the wall charger to a lower current setting. There is nothing wrong with tripping the breakers. That is what they are there for, to protect against over current. The 50 amp breaker is not there to protect your whole sub panel. It is there to protect the wire run from this breaker to the wall charger only.
 
Honestly I feel there is so much bad information being thrown around in this thread I would suggest deleting the entire thread and starting over.
I’ve had some good bits though. I discussed with my friend yesterday afternoon and based on the load calc and how we use the garage we’re going to go with a 50amp. He said the inspector should be totally fine with it, and if for some reason I need to use some heavy tools that will draw more than about 15 extra amps (all the garage lights add up to a measly 1.5 amps all LED) to either stop charging for the 20 min or so while I’m doing it or change the Tesla’s intake settings.

For anyone reading this thread in the future - this is what we’ve done. Obviously, I’d recommend using an electrician (or at least like in our case someone who has taken the coursework and is actively apprenticing under supervision).

  • Full load calculation was done on the main panel and sub panel to make sure things were right as-is (we counted lights, appliances, wall outlets, etc). He suggested and we already made a few changes to our main panel to make things more efficient and remove a few things we’re pretty sure some previous owner did without anyone knowing (like off-brand breakers and outlets single-wired to a breaker that could be strung into one).We have a modestly sized home about 2,000 sq ft (1.5 story cape cod with a finished basement all gas appliances except the AC so no need to up our service at this time from 125amp). What may also differentiate us is all our light fixtures were upgraded to high efficiency LEDs (lots of Halo lights); our average monthly electric bill is about $50 in no -AC time and $85 using AC.
  • We measured the wire distance from the main panel to the garage sub panel to make sure whatever is there is sufficient and the voltage drop wouldn’t cause problems (fortunately all in the unfinished part of the basement so easy to do). Previous homeowner had a 6 awg wire going to the panel, which is not optimal for a 60amp sub panel but I guess a lot of inspectors would let it pass assuming standard load buffers (0.8 rule) but WCS the inspector might ask us to up it to a 4 awg as part of our install or make make it a 50amp panel since we’re messing the with sub panel anyway. In our case btw voltage drop from the main to then sub is only 1.8% so well within acceptable range.
  • We need to use a 6 awg wire bundle for the charger regardless because of local code, even on a 50 or 40 amp breaker. This charger is going to be within 6 feet of the sub panel so shouldn’t be too bad in terms of wire pricing. We only have a one car garage, but we opted for the 18ft cable so we could charge in the driveway as well.
Thanks so much to all! I’ll update how it all goes. We’re considering asking Tesla if an overnight test drive is possible so we can test our charging setup prior to delivery.
 
I have 100A service in my decent-sized house (Natural gas heat, but electric water heater) and I have a 50A breaker 96Ga, so 40A draw for charging) for the Gen2 charger.
I have simply scheduled my charging to start at 1AM. I don't think I've ever gone out at 8AM and needed to unplug while charging, and if I've been on an extended trip and need the car I can start charging any time, even in Canadian winters where you use up to 3:1 mileage.
40A charges at 57km/hr; so from 1AM to 8AM that's more than a full 80% charge. I seriously doubt I'll be using the dishwasher, oven, dryer and toaster or coffeemaker at 1AM. Rarely am I using AC at that hour, and unless I have a late shower, probably not using the hot water tank. These too should not draw 60A anyway; I've never popped the main breaker or the charger breaker in over 2 years.

Another point - I hooked my Gen2 using a 50A-rated oven cord with a NEMA 14-50 plug - to simplify the install, and leave me the option of using the portable charger if the Gen2 has a problem. It also means I have a NEMA 14-50 socket in the garage should I ever need to plug in extreme power tools...
 

mswlogo

Well-Known Member
Aug 27, 2018
7,471
6,939
MA, NH
For day to day usage 99% of the time you wouldn’t notice the difference in 40A vs 50A. So it finishes charging at 2AM vs 4AM.

The only time it matters is when you are in a hurry. You come home from a long commute and you want to leave that evening for say a weekend trip. But the thing is, 50A might not be fast enough in those situations either (both are “level 2”). That’s what super charging is for.

it will be very rare that 50A vs 40A will make the difference you need.
 
UPDATE - we’re done! The inspection is scheduled for next Friday to close the permit, but we should be good to go, I imagine.

We decided to go with a 40amp breaker and downgrade the subpanel to 50amp. Primarily this is because when we tested the wire it measured at 6 awg rather than 4 awg, so because we’re doing new work and this is definitely a new inspector from when this panel was first installed, we didn’t want to run the risk of failing and having to buy more materials. I can deal with 7 less mph charge when I’m basically getting 30 with the Y on a 40amp. That and now we’re better protected in the event of a surge (from a wiring perspective).

Wiring for the wall connector is 6awg through conduit. We mounted on plywood so we’d have more flexibility on the location. We also mounted closer to the panel to save $250 (electrical wire is through the roof now); that 18ft cable reaches across the garage just fine with room to spare.

Now that that’s done, Elon just needs to get me a VIN :).
 

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It’s a little bit of a mess. The previous homeowner had all sorts of “toys” hardwired in that he took with him when we bought the house a year ago (he used the garage as a workshop). This panel looks full but when we do the charger we’re taking out everything that’s currently switched to off (2,4,6,9,10). They’re all breakers without wiring so not loosing anything. I imagine he‘ll use 2,4 for the double pole 50 or 40 breaker. He also mentioned that the garage door doesn’t need to be on a 20amp.

View attachment 657103

We have the option of signing up for time of use. We haven’t given we’re working at home until the end of the pandemic. We’re in central NJ so there are plenty of super chargers and L2s around, just more convenient and cheaper to do at home (minus the upfront cost of material of course!)
What kind of inspection is required if it’s required, I’m in central New Jersey as well and I’m planning to do installation myself.
 

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