HPWC on 12/2 Romex

[wtfuzz]

I'm still waiting on my AWD Model 3 and HPWC to arrive. In the meantime I'm thinking of ways to install the HPWC.

My house entrance has a 240V fan/heater in the wall that we never use. The heater backs onto the garage wall, and is on a dedicated 20A breaker wired with 12/2 Romex. I could easily remove the heater and punch the wire through a hole into the garage.

My service is 125A, so I do plan on getting an electrician to replace my meter box, breaker panel, and possibly the wires to the pole out front if necessary for a 200A upgrade and a sub panel in the garage with 60A to the HPWC at some point.

I'm wondering if anyone charges at 240V 20A and if it's worth it to do the temporary install, or just go straight for the 60A. My wife and I both work from home, so we mostly just drive casually.

 

[P85_DA]

U can do a 5-20 but that’s on 120 not 240

 

[wtfuzz]

U can do a 5-20 but that’s on 120 not 240

The HPWC has a selector switch that will run at 240V 20A

 

[wtfuzz]

 

[F14Scott]

You'd be charging at 16A/240VAC, which in your AWD would mean about 15 MPH. That's almost certainly enough for home charging, if you don't commute.

Google Image Result for https://shop.tesla.com/content/dam/tesla/CAR_ACCESSORIES/MODEL_3/CHARGING_ADAPTERS/NEMA_Gen2.png

You'd need a NEMA 6-20 plug installed and an adapter for your UMC from Tesla. But, you might even skip the HPWC.

 

[wtfuzz]

You'd be charging at 16A/240VAC, which in your AWD would mean about 15 MPH. That's almost certainly enough for home charging, if you don't commute.

Google Image Result for https://shop.tesla.com/content/dam/tesla/CAR_ACCESSORIES/MODEL_3/CHARGING_ADAPTERS/NEMA_Gen2.png

You'd need a NEMA 6-20 plug installed and an adapter for your UMC from Tesla. But, you might even skip the HPWC.

Thanks. The HPWC is already ordered and on the way, so I think I'll just stick with that (also would be nice to always keep the UMC in the car for those spontaneous road trips). I was hoping I could just run the romex into the HPWC through the rear entry conduit port and wire it directly to the terminal blocks.

Any issues with this? ie is 12AWG too small for the terminals which I assume are large to accept up to 3AWG?

 

[F14Scott]

Thanks. The HPWC is already ordered and on the way, so I think I'll just stick with that (also would be nice to always keep the UMC in the car for those spontaneous road trips). I was hoping I could just run the romex into the HPWC through the rear entry conduit port and wire it directly to the terminal blocks.

Any issues with this? ie is 12AWG too small for the terminals which I assume are large to accept up to 3AWG?

I think you'll be fine.

 

[ucmndd]

Agree, it will work fine. Just set the rotary dial to the right spot and you’re golden

 

[iluvmacs]

U can do a 5-20 but that’s on 120 not 240

...which is why NEMA created 6-20...

 

[AlanSubie4Life]

Any issues with this? ie is 12AWG too small for the terminals which I assume are large to accept up to 3AWG?

Your plan seems fine. Unless you have a long commute, or extreme cold where you want lots of pre-warming of the vehicle, I think you’ll find that ~3.8kW of charging is fine most of the time. Looks like you are in a place where electricity is cheap most likely, so you don’t need to worry about fitting all your charging into a short overnight “cheap” window on a time-of -use plan. Just plug in whenever you are home!

Just check the wiring integrity of course - I would think that for a heater it would have to be pretty solid though.

I just brought Romex right into the back of mine with a standard screw-in clamp for the wire screwed into the Wall Connector (I know this is not the clamp you were talking about). It was 6AWG, but I don’t think you will have any problem with the terminals with 12AWG. They are a robust clamping type and will work fine with a small wire. My terminals were fully clamped when I got my HPWC - and it is a little hard to tell whether they are fully clamped or fully unclamped, so if the tightening screws won’t turn clockwise, turn counterclockwise to fully loosen before inserting the wire! Took me a few minutes to figure that out...

The smaller wire will make it a lot easier to wire up! Obviously, select position 2 for the rotary setting.

 

[ewoodrick]

I believe that you may find that a 240V 20A is more than enough to charge and that replacing your meter and panel is a LOT of money.

And by replacing the panel, gas would be a lot cheaper to drive

 

[Runt8]

I believe that you may find that a 240V 20A is more than enough to charge and that replacing your meter and panel is a LOT of money.

And by replacing the panel, gas would be a lot cheaper to drive

I’m saving about $100 month on electricity vs gas (actually more now that gas prices have been going up), so a panel and meter upgrade would only take me a couple years break even.

But it is very possible that 240 20 is enough.

 

[mswlogo]

I'm still waiting on my AWD Model 3 and HPWC to arrive. In the meantime I'm thinking of ways to install the HPWC.

My house entrance has a 240V fan/heater in the wall that we never use. The heater backs onto the garage wall, and is on a dedicated 20A breaker wired with 12/2 Romex. I could easily remove the heater and punch the wire through a hole into the garage.

My service is 125A, so I do plan on getting an electrician to replace my meter box, breaker panel, and possibly the wires to the pole out front if necessary for a 200A upgrade and a sub panel in the garage with 60A to the HPWC at some point.

I'm wondering if anyone charges at 240V 20A and if it's worth it to do the temporary install, or just go straight for the 60A. My wife and I both work from home, so we mostly just drive casually.

You can do 12-2 20A 240V just fine. That is the beauty of the wall connector. You can dial it to what ever you want. No GFCI needed, more rugged for outdoor use and you can upgrade amperage when it’s most convenient.

 

[wtfuzz]

I believe that you may find that a 240V 20A is more than enough to charge and that replacing your meter and panel is a LOT of money.

And by replacing the panel, gas would be a lot cheaper to drive

I also want to upgrade the panel for other loads. It’s a 125A service from the 80s, and I want to add mini split AC units to the home. It was on my todo list before we decided to get a Tesla

For now I’ll likely use the 240V 20A since it’s already there.

 

[wtfuzz]

Your plan seems fine. Unless you have a long commute, or extreme cold where you want lots of pre-warming of the vehicle, I think you’ll find that ~3.8kW of charging is fine most of the time. Looks like you are in a place where electricity is cheap most likely, so you don’t need to worry about fitting all your charging into a short overnight “cheap” window on a time-of -use plan. Just plug in whenever you are home!

Just check the wiring integrity of course - I would think that for a heater it would have to be pretty solid though.

I just brought Romex right into the back of mine with a standard screw-in clamp for the wire screwed into the Wall Connector (I know this is not the clamp you were talking about). It was 6AWG, but I don’t think you will have any problem with the terminals with 12AWG. They are a robust clamping type and will work fine with a small wire. My terminals were fully clamped when I got my HPWC - and it is a little hard to tell whether they are fully clamped or fully unclamped, so if the tightening screws won’t turn clockwise, turn counterclockwise to fully loosen before inserting the wire! Took me a few minutes to figure that out...

The smaller wire will make it a lot easier to wire up! Obviously, select position 2 for the rotary setting.

Electricity is much cheaper here. Premium gas in our BMW runs $110-120, and my GTI is $80+ per tank at around $1.70/litre or $6.40/gallon. Some months we easily spend $500 on gas, and we don’t commute; purely pleasure driving.

Electricity costs $0.09/kWh for the first 1350, then $0.14/kWh. No TOU billing - all flat rate.

 

[eprosenx]

I'm still waiting on my AWD Model 3 and HPWC to arrive. In the meantime I'm thinking of ways to install the HPWC.

My house entrance has a 240V fan/heater in the wall that we never use. The heater backs onto the garage wall, and is on a dedicated 20A breaker wired with 12/2 Romex. I could easily remove the heater and punch the wire through a hole into the garage.

My service is 125A, so I do plan on getting an electrician to replace my meter box, breaker panel, and possibly the wires to the pole out front if necessary for a 200A upgrade and a sub panel in the garage with 60A to the HPWC at some point.

I'm wondering if anyone charges at 240V 20A and if it's worth it to do the temporary install, or just go straight for the 60A. My wife and I both work from home, so we mostly just drive casually.

Your plan is a good one. The Wall Connector is overkill for just a 20a circuit, but as you point out, you can easily upgrade to a 60a or greater circuit later. 20a (actually 16a) 240v is that absolute minimum I work recommend for home charging for most folks. It may get you by until you do that upgrade.

It drives me crazy that the Wall Connector manual does not outline allowed wire gauges in the terminals. That is insane. Every electrical device does that. I had to email them to ask what the max gauge is (it is 2 awg copper btw). I have never asked about minimum, but since it can crank down to as low as a 15a circuit, I suspect as low as 14awg is fine (clamp style terminals are very forgiving).

Make sure too don’t have a Federal Pacific or Zinsco panel. They are fire hazards.

Btw, if spending the money on a service upgrade, do the math and figure out if 200a is enough. You may even want to jump to the next size up (typically 320a continuous load).

Good luck! Welcome to Tesla ownership!

 

[linkster]

I also want to upgrade the panel for other loads. It’s a 125A service from the 80s, and I want to add mini split AC units to the home. It was on my todo list before we decided to get a Tesla

For now I’ll likely use the 240V 20A since it’s already there.

Even though Veronica can gulp a full 80a and I have (3) HPWCs, I charge her and the LR RWD M3 using a Gen II MC with 6-20 adapters 99% of the time. The HPWCs are mostly for guests. I really dislike pulling and working with unruly 3 and 4ga. cable when a 30/24a 10ga. or a 20/16a 12ga. will suffice and is a pleasure to work with.

I went with a 2.5 ton Mitsubishi mini-split for the garage and that rascal only sips 21a with basically zero startup surge.

Good - luck.

 

[mswlogo]

Even though Veronica can gulp a full 80a and I have (3) HPWCs, I charge her and the LR RWD M3 using a Gen II MC with 6-20 adapters 99% of the time. The HPWCs are mostly for guests. I really dislike pulling and working with unruly 3 and 4ga. cable when a 30/24a 10ga. or a 20/16a 12ga. will suffice and is a pleasure to work with.

I went with a 2.5 ton Mitsubishi mini-split for the garage and that rascal only sips 21a with basically zero startup surge.

Good - luck.

10 AWG is usually solid. 6 to 8 AWG is about as easy to work with because it’s stranded. 4 and up can be knuckle scraping

 

[Webeevdrivers]

I'm still waiting on my AWD Model 3 and HPWC to arrive. In the meantime I'm thinking of ways to install the HPWC.

My house entrance has a 240V fan/heater in the wall that we never use. The heater backs onto the garage wall, and is on a dedicated 20A breaker wired with 12/2 Romex. I could easily remove the heater and punch the wire through a hole into the garage.

My service is 125A, so I do plan on getting an electrician to replace my meter box, breaker panel, and possibly the wires to the pole out front if necessary for a 200A upgrade and a sub panel in the garage with 60A to the HPWC at some point.

I'm wondering if anyone charges at 240V 20A and if it's worth it to do the temporary install, or just go straight for the 60A. My wife and I both work from home, so we mostly just drive casually.

We routinely charge at 240 volt 12 Amp on a 15 amp circuit. More than covers our needs. Depends on your daily commute.

 

[mswlogo]

We routinely charge at 240 volt 12 Amp on a 15 amp circuit. More than covers our needs. Depends on your daily commute.

If all I ever did was use my car to go to work it would be fine. But I use it every chance I get. Since I have solar to cover the car I prefer not super charge either.