Model S - HPWC (High Power Wall Connector)

[WilliamG]

Yep, here you go:

amps cuts to 31 now...

So... as far as I know my amps have been 32 since new. never had an issue that I know of. Now the app, which shows and lets you change charge rate.... when I open it at random shows 31. wtf? i set it to 32 and randomly (almost every time actually) it's showing 31... why?!?! 32 is slow enough. I...

teslamotorsclub.com

(Edit) Ah, and I see that you found it and added a comment there.

Thank you, and yes - I did find it (surprisingly easily, actually!). Was expecting a battle. Thanks!

 

[jm404]

Unless you have an enormously long run, there is little cost difference between 6awg and 4awg. I went ahead and ran 4awg (xhhw-2) and can theoretically could install an >80 amp charger in the future. It is slightly more difficult to run compared to 6, but I'm very glad I went ahead with 4awg.

 

[N4HHE]

Unless you have an enormously long run, there is little cost difference between 6awg and 4awg. I went ahead and ran 4awg (xhhw-2) and can theoretically could install an >80 amp charger in the future. It is slightly more difficult to run compared to 6, but I'm very glad I went ahead with 4awg.

Use 2 AWG SEL (Service Entrance, about $1.50/foot for 2 conductors plus ground) aluminum even if you have to add a disconnect box for an easy junction between aluminum to 4 or 6 AWG copper the last few feet to the WC.

First generation HPWC terminals supported aluminum or copper.

 

[Jeffsstuff]

Ok, I hope this is the right place for this.

I just replaced my 2013 model S with a 2022 model s.
my HPWC (gen 1 I believe) is connected to a 50 amp breaker via #6 wire which, as I understand it, is good for up to 65A.
I understand the need to derate the ampacity by 20% if a continuous load.

So I could replace the 50A breaker with a 60, and change the DIP switches in the HPWC to supply 48A To the car.

my question is, is replacing the breaker necessary? Wouldn’t the 50A breaker work fine in this situation since I would draw, at most, 48A?

 

[jerry33]

Ok, I hope this is the right place for this.

I just replaced my 2013 model S with a 2022 model s.
my HPWC (gen 1 I believe) is connected to a 50 amp breaker via #6 wire which, as I understand it, is good for up to 65A.
I understand the need to derate the ampacity by 20% if a continuous load.

So I could replace the 50A breaker with a 60, and change the DIP switches in the HPWC to supply 48A To the car.

my question is, is replacing the breaker necessary? Wouldn’t the 50A breaker work fine in this situation since I would draw, at most, 48A?

No. EV charging is a continuous load so it’s derated 20%. A 60 amp circuit will charge a BEV at 48 amps maximum.

 

[Jeffsstuff]

I get that it is derated and the wire is in fact heavy enough for 65 A. My question is why is it necessary to increase the breaker size?

 

[jerry33]

I get that it is derated and the wire is in fact heavy enough for 65 A. My question is why is it necessary to increase the breaker size?

If you use a 50 amp breaker then you will only be able to charge 40 amps maximum.

 

[Jeffsstuff]

Again, I ask why? I don’t see how it is unsafe (the breaker is going to limit current to 50 instead of 60 amps).

 

[jerry33]

Again, I ask why? I don’t see how it is unsafe (the breaker is going to limit current to 50 instead of 60 amps).

Two reasons. The 50 amp breaker is not designed for continuous loads of 50 amps so it will overhat and fail. The other is that the inspector an insurance company (if there should be a problem) will look at the breaker size. I don’t understand why you wnt to go against code.

 

[MP3Mike]

I don’t understand why you wnt to go against code.

Especially to only save like $30 for a new breaker.

 

[Jeffsstuff]

Two reasons. The 50 amp breaker is not designed for continuous loads of 50 amps so it will overhat and fail. The other is that the inspector an insurance company (if there should be a problem) will look at the breaker size. I don’t understand why you wnt to go against code.

And that’s a reason I can accept. I just wanted to make sure I wasn’t doing extra work for nothing.
I wasn’t looking to cheap out or disagree with anyone. I just wanted to understand the rationale to make sure I wasn’t doing unnecessary work and buying unnecessary componentry.

 

[henderrj]

By the way, the breaker does not limit the amount of current. It simply trips if there's too much going through. It also overheats potentially causing a fire, so that's why you shouldn't do that.

 

[davewill]

Ok, I hope this is the right place for this.

I just replaced my 2013 model S with a 2022 model s.
my HPWC (gen 1 I believe) is connected to a 50 amp breaker via #6 wire which, as I understand it, is good for up to 65A.
I understand the need to derate the ampacity by 20% if a continuous load.

So I could replace the 50A breaker with a 60, and change the DIP switches in the HPWC to supply 48A To the car.

my question is, is replacing the breaker necessary? Wouldn’t the 50A breaker work fine in this situation since I would draw, at most, 48A?

What kind of #6 wire? Romex is only good for 50a, and you'd have to stay where you are. THHN in conduit is good for a 60a circuit.

 

[tga]

And that’s a reason I can accept. I just wanted to make sure I wasn’t doing extra work for nothing.
I wasn’t looking to cheap out or disagree with anyone. I just wanted to understand the rationale to make sure I wasn’t doing unnecessary work and buying unnecessary componentry.

Circuit ratings in North America are based on intermittent, not continuous, ratings (Europe uses continuous). Cont = int * 0.80, int = cont * 1.25. A 50A circuit in NA is an intermittent rating. The continuous equiv is 40A.

Breakers have a time curve, and will trip if you draw more than X for Y seconds. For a 50A breaker, X is 40A for >3hrs (definition of continuous load), X=50A, Y=a few seconds, and X=a few hundred amps (short), Y=0 sec.

You might think that "well, I'll only charge for 1 hr. That's less than 3hrs, so it doesn't meet the continuous rule, right?" But the NEC says that any EV charging, regardless of duration, must be treated as a continuous load.

EV charging is the most "stressful" thing you will likely encounter in residential environment. Pretty much everything else falls under the intermittent loads (even heating elements generally cycle on and off).

What kind of #6 wire? Romex is only good for 50a, and you'd have to stay where you are. THHN in conduit is good for a 60a circuit.

Expanding on this, 6ga copper has different ratings at different temps (all ratings are intermittent). 60 deg C = 55A, 75 deg C = 65A, 90 deg C = 75A. You can only use the lowest degree C rating for all components in the circuit. For residential, that's either the 75C ratings of your breaker, or the 60C rating of romex. THHN in conduit is good for 90C, but your breaker terminals aren't, so you would be limited to 75C=65A with THHN.

You are allowed to round up the rating for non-standard breaker sizes (so a 60A breaker on #6 romex, 70A breaker on THHN/conduit), but that's only for the breaker, not the circuit rating as a whole - the wire is still the limiting factor.

 

[Jeffsstuff]

Circuit ratings in North America are based on intermittent, not continuous, ratings (Europe uses continuous). Cont = int * 0.80, int = cont * 1.25. A 50A circuit in NA is an intermittent rating. The continuous equiv is 40A.

Breakers have a time curve, and will trip if you draw more than X for Y seconds. For a 50A breaker, X is 40A for >3hrs (definition of continuous load), X=50A, Y=a few seconds, and X=a few hundred amps (short), Y=0 sec.

You might think that "well, I'll only charge for 1 hr. That's less than 3hrs, so it doesn't meet the continuous rule, right?" But the NEC says that any EV charging, regardless of duration, must be treated as a continuous load.

EV charging is the most "stressful" thing you will likely encounter in residential environment. Pretty much everything else falls under the intermittent loads (even heating elements generally cycle on and off).



Expanding on this, 6ga copper has different ratings at different temps (all ratings are intermittent). 60 deg C = 55A, 75 deg C = 65A, 90 deg C = 75A. You can only use the lowest degree C rating for all components in the circuit. For residential, that's either the 75C ratings of your breaker, or the 60C rating of romex. THHN in conduit is good for 90C, but your breaker terminals aren't, so you would be limited to 75C=65A with THHN.

You are allowed to round up the rating for non-standard breaker sizes (so a 60A breaker on #6 romex, 70A breaker on THHN/conduit), but that's only for the breaker, not the circuit rating as a whole - the wire is still the limiting factor.

Thanks! I beleive what Is there is in (flexible) conduit (looks like bx but larger… I didn’t install it, so I’m not 100% sure what it is. I read the gauge of the conductors from inside the box.

so for now I’ll stick with 40A and if I get ambitious, perhaps one day I’ll swap out the breaker for a 60A and change the HPWC to 48A. For now, it seems unimportant.

i’m sure I’m going to regret asking this one but, I’m using what I think is the initial version of the wall connector. Through the referral program I ended up with a second wall connector which is newer I don’t know if it’s second or third generation. Is there any advantage to swapping that out or should I just do what I’ve been doing all along (keeping it in storage in case something goes wrong with the one I’m using)?

 

[brkaus]

Thanks! I beleive what Is there is in (flexible) conduit (looks like bx but larger… I didn’t install it, so I’m not 100% sure what it is. I read the gauge of the conductors from inside the box.

so for now I’ll stick with 40A and if I get ambitious, perhaps one day I’ll swap out the breaker for a 60A and change the HPWC to 48A. For now, it seems unimportant.

i’m sure I’m going to regret asking this one but, I’m using what I think is the initial version of the wall connector. Through the referral program I ended up with a second wall connector which is newer I don’t know if it’s second or third generation. Is there any advantage to swapping that out or should I just do what I’ve been doing all along (keeping it in storage in case something goes wrong with the one I’m using)?

If it's a newer one, it would have the ability to load share. Of course, that would require purchasing yet another matching WC.

I'd just leave it in the box as a backup.

 

[tpedwards]

Gen 2 HPWC can handle up to 80 amps as long as your wiring and breaker are rated for 100 amps. I had this setup for my 2013 P85 that had dual chargers. I can count on one hand the times that it was useful. Typically those were race home and charge while loading the car for a road trip. Even then, I was typically topping off which means I was in charge taper range anyway. I have since moved and upgraded to a 2015 P85D that does not have dual chargers. Needless to say when I reinstalled the HPWC I only opted for 50 amp service and only charge at 40 amps.

 

[Jeffsstuff]

Okay, maybe mine is gen 2 because it does support 80A. I never had dual chargers so it wasn’t an issue for me. The new one in the box is likely 3rd gen then.

 

[zoomer0056]

Ok, I hope this is the right place for this.

I just replaced my 2013 model S with a 2022 model s.
my HPWC (gen 1 I believe) is connected to a 50 amp breaker via #6 wire which, as I understand it, is good for up to 65A.
I understand the need to derate the ampacity by 20% if a continuous load.

So I could replace the 50A breaker with a 60, and change the DIP switches in the HPWC to supply 48A To the car.

my question is, is replacing the breaker necessary? Wouldn’t the 50A breaker work fine in this situation since I would draw, at most, 48A?

The Tesla Wall Connector says to use a 60 amp. Do as recommended, dont second guess it. I think your 50 amp breaker would be tripped with a 48amp current.

 

[jerry33]

Gen 2 HPWC can handle up to 80 amps as long as your wiring and breaker are rated for 100 amps. I had this setup for my 2013 P85 that had dual chargers. I can count on one hand the times that it was useful. Typically those were race home and charge while loading the car for a road trip. Even then, I was typically topping off which means I was in charge taper range anyway. I have since moved and upgraded to a 2015 P85D that does not have dual chargers. Needless to say when I reinstalled the HPWC I only opted for 50 amp service and only charge at 40 amps.

The 80 amps were mainly useful as home based PlugShare charging locations. I used them a few times on trips before SCs were available.