HPWC Charger installation question

[MnInvsve]

hi everyone,

Really excited to be picking up my model 3 next Saturday (blue - VIN 36xx) and am trying make sure im set up for charging. our home is relatively new and the garage was prewired with for an electric car charger. when we purchased the house, I had asked the contractor to place a NEMA 14-50 outlet where the pre-wire was.

My plan for now is that I can use the mobile connector with the NEMA 14-50 outlet for the new car.

I looked at the wiring run and it looks like the cabling that goes from the outlet to the main panel is labeled “Romex AWG 2 CU 3 CDR WITH AWG 8 GROUND TYPE NM-B MAX 600 VOLTS”.

We have 200 amp service. From what I can tell, this wiring should be able to handle 100 AMPS. Is that correct?

If I wanted to install a HPWC, would it just be a matter of switching out the breaker to a higher amperage and the outlet to the HPWC?

Is this worth doing or do many people just use the mobile charger with the outlet?

Thanks for any feedback!!

 

[Robotpedlr]

What is the charger spec in the Model 3? If its 40amp then the most you need to spec for is a 50amp system (breaker, wire, etc). No reason to plumb for a higher system if you car is limited to 40amp. (FYI - whatever the charger rating is of your car, you multiple that by 125% to spec the components). The HPWC has an adjustment you can set to specific amp ratings.

 

[MnInvsve]

What is the charger spec in the Model 3? If its 40amp then the most you need to spec for is a 50amp system (breaker, wire, etc). No reason to plumb for a higher system if you car is limited to 40amp. (FYI - whatever the charger rating is of your car, you multiple that by 125% to spec the components). The HPWC has an adjustment you can set to specific amp ratings.

I think it’s 48amp in the model 3. I think setting up the HPWC with 60amp wiring would allow you to charge at 48A.

 

[brkaus]

Really excited to be picking up my model 3 next Saturday (blue - VIN 36xx) and am trying make sure im set up for charging. our home is relatively new and the garage was prewired with for an electric car charger. when we purchased the house, I had asked the contractor to place a NEMA 14-50 outlet where the pre-wire was.

Smart move!!!

My plan for now is that I can use the mobile connector with the NEMA 14-50 outlet for the new car.

That will work fine.

looked at the wiring run and it looks like the cabling that goes from the outlet to the main panel is labeled “Romex AWG 2 CU 3 CDR WITH AWG 8 GROUND TYPE NM-B MAX 600 VOLTS”.

I'm surprised that the ground is allowed to be so much smaller than the main cables, but if that really is the marking... Are the 3 main conductors very large?

I don't think AWG 2 NM-B is rated for 100A. The tables I have found indicate 95 max, but I AM NOT AN ELECTRICIAN!

We have 200 amp service. From what I can tell, this wiring should be able to handle 100 AMPS. Is that correct?

The table I found shows AWG 2 NM-B Romex is good for 95 amps max. I believe it has to be derated by 20% for a continuous load.

The size of the wiring to the outlet isn't the only consideration. To understand how much additional load you can put on your 200A service, you would technically need to do a load calculation. It takes into consideration the load currently on the system. Heat, oven, dryer, lighting, etc.

If I wanted to install a HPWC, would it just be a matter of switching out the breaker to a higher amperage and the outlet to the HPWC?

Yes, but you would need to determine the proper breaker size for your wiring and set the switch inside the HPWC to the correct value.

Is this worth doing or do many people just use the mobile charger with the outlet?

The EVSE that comes with the car will charge a max rate of 32A on a 14-50.

A 14-50 can charge a max rate of 40A (with an old GEN1 style EVSE).

The car has a 48A internal charger, so an HPWC on a 60A circuit would charge at the maximum rate the car can support.

 

[CameronB]

I'll second what @brkaus said, particularly about the outlet wiring and breaker not being the only consideration. Definitely should get a load calculation done.

We also have 200amp service and I wanted to get 100amp installed for a HPWC. Even though our home is 100% Energy Star appliances and 100% LED lighting and otherwise relatively energy saving, still could not get the rest of the usage below 100amp to give a full 100 amp circuit for the HPWC. Did manage to get a 90amp circuit.

My idea was to get the optional 72amp high speed charger and a 90 amp circuit would let me pretty much get that continuously.

In the end, I haven't opted to buy that high speed charger (my car can add it later for additional $) because I have found even at 48amp, it's still plenty fast for my charging needs.

So I definitely over "built" for what I ended up with...or did I? The one additional thing that extra "unneeded" amperage overhead on your circuit could provide, is if in the future maybe you end up becoming a two Tesla household. HPWC can be "daisy chained" together and if we end up getting another Tesla (a possibility), then we can simply install a second HPWC on the existing circuit and the two cars can both charge simultaneously at about 35-38 amps max. And if you hook HPWCs in a daisy chained fashion like that and are not charging both cars at the same time, then it will divert maximum amps (48 or whatever your maximum is) to the single car.

Basically works like a mini supercharger (Plug into "A" alone, get "full" speed, share with "B", have some smart splitting of power). At least that's how I understand it.

So while I generally agree with the above where saying that 60A circuit will give your Model 3 as much as it can take (true), if there is a potential that in the future you might get a second Tesla, then perhaps a larger circuit could give some benefit. Otherwise, yeah, just get the 60A setup and save some money.

 

[brkaus]

BTW - you should be just fine with the 14-50 and the included EVSE. I would use that for a while and decide if it is worth the extra money.

I always left mine plugged in. When out I used the J1772 adaptor, except when visiting family in other cities. Then I brought along the portable EVSE.

 

[TexasEV]

My advice, after 4 1/2 years of Model S ownership, is use your 14-50 outlet which is already installed. Keep the UMC plugged into it and install a bicycle or utility hook next to the outlet to hang the cord. You only need to unplug and take the UMC with you when you're driving out of town (and even then you're not likely to use it, with so many superchargers now). With the range of the Model 3 there are no charging "emergencies" with normal driving that people worry about who say they always want the UMC with them. People who write that have never owned a long range EV, it seems.

 

[Nosken]

The Model 3 LR can only charge at 40-amps. The Regular Model 3 will only charge at 32 -amps. The new Mobile Connector only outputs 32-amps. You could purchase the original UMC (universal Mobile Connector) that charges at 40-amps.

A look at Tesla Model 3 charging options

When I bought my first Model S in 2014. It had dual chargers capable of 80-amps. I ordered a wall charger with the car. When the electrician was quoting my install, they informed me that it would cost 3 times as much to install, since, being capable of higher amperage, it needed a visible cut off and my panel wouldn't handle it. I set my charge rate to 35-amps for better charging efficiency, and it is always fast enough.
I had mistakenly assumed that if I used a 14-50 and the UMC, that I would have to unplug and take it with me every day, then re-plug at night. This is not the case, the only time I take my UMC with me is on long overnight trips. In over 80,000 electric miles, I have never had to use the UMC except at home. I always have my J1772 adapter with me-just in case.
Wall Chargers look great, but are unnecessary for typical Model 3 use. Just have fun with your Tesla.

 

[TexasEV]

The Model 3 LR can only charge at 40-amps.

Not correct. The long range Model 3 has a 48A charger. The initial publicity on the Model 3 said 40A charging when plugged into 240V outlet-- that was referring to a 14-50 outlet (with the older style UMC)--but it neglected to mention it could charge at 48A when plugged into a HPWC!

 

[Nosken]

Not correct. The long range Model 3 has a 48A charger. The initial publicity on the Model 3 said 40A charging when plugged into 240V outlet-- that was referring to a 14-50 outlet (with the older style UMC)--but it neglected to mention it could charge at 48A when plugged into a HPWC!

Thank you for the correction.

 

[03DSG]

Thank you for the correction.

To charge at 48 amps on Tesla’s HPWC you would need a 60 amp circuit breaker and 6/3 wire.

 

[brkaus]

To charge at 48 amps on Tesla’s HPWC you would need a 60 amp circuit breaker and 6/3 wire.

It appears the OP has 2 ga romex. So 60A should be easy. Assuming label read correctly.

I'd still stick with the EVSE unless higher need is proven.

 

[MnInvsve]

It appears the OP has 2 ga romex. So 60A should be easy. Assuming label read correctly.

I'd still stick with the EVSE unless higher need is proven.

Thanks for all the replies. Think it’s best to stick with the UMC and see how it goes before spending additional $$ to upgrade. Sounds like it I did install a HPWC it would be advantageous to go as high as possible on the breaker size in case we ever get a second car, etc.

 

[03DSG]

Thanks for all the replies. Think it’s best to stick with the UMC and see how it goes before spending additional $$ to upgrade. Sounds like it I did install a HPWC it would be advantageous to go as high as possible on the breaker size in case we ever get a second car, etc.

As you increase breaker size so do you increase wire size so if you plan a 100 amp breaker you will need compatible wire to handle that potential current. That starts to get expensive. Worth it though if you plan on more than one Tesla and plan to load share through two HPWC. If it’s for one Tesla and one (something else) you could run the 100 amp circuit to a sub panel in the garage and use a 60 amp breaker for the 48 amp HPWC for the Tesla and an additional 40 amp breaker to supply 32 amps to a Nema 14-50 or another EVSE for the other vehicle.

 

[israndy]

To charge at 48 amps on Tesla’s HPWC you would need a 60 amp circuit breaker and 6/3 wire.

I am seeing Romex wire for a 60 amp circuit to feed the HPWC would be 6/2 as the neutral wire is NOT used by the HPWC. So unless you plan on feeding something, OTHER than the charger, that needs 110v, you don't need that extra cost for the extra wire.

-Randy

 

[03DSG]

I am seeing Romex wire for a 60 amp circuit to feed the HPWC would be 6/2 as the neutral wire is NOT used by the HPWC. So unless you plan on feeding something, OTHER than the charger, that needs 110v, you don't need that extra cost for the extra wire.

-Randy

Correct. I ran a surface run of Teck90 armoured 6/3awg on a 40 amp breaker 75 feet from my basement panel to a Nema 14-50 in the garage. The Nema 14-50 requires 3 wire plus ground. This will allow me to charge the Model 3 at 32 amps using the included Gen 2 UMC and any other visiting EV in the meantime.
Once the car arrives and I have a VIN I can apply for the Provincial $1000 grant for an EV charging station. At that time I remove the Nema 14-50 buy and install a HPWC and replace the 40 amp breaker with a 60 amp breaker. At that point I have one unused wire.
For the Minimal difference in price between 6/2 and 6/3 it gives me more downline options without the potential of a wire rerun.