Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register
  • TMC Podcast #11 will stream live Saturday at 1PM PDT. We will be joined by special guest JT Stukes, a former engineer at Tesla. You can watch it live and participate in the chat on YouTube. We will addressing viewer comments and questions. For more information, follow the TMC Podcast #11 thread.

Difficult situation with a Condo, advice appreciated...

Hi everyone! I recently took delivery of a Tesla Model 3 Long Range, and I love it!

Unfortunately, it seems that I should have done more homework when it comes to charging. I live in a 1970's condo unit in Los Angeles and I'm trying to get home charging installed. My HOA is receptive to me installing charging, so that's not an issue. My two issues are

1) My electrical meter is over 400 feet away from my parking spot. That means that my cabling might be expensive. However, my actual apartment (which has my electrical panel) is directly above my parking space.

2) My unit's main breaker is only 70A.

I spoke to two electricians so far. The first one came out and was the one who measured the distance. He said he would upgrade my main breaker to 100A and then run the power all the 400 ft to my space for $5700! That was a LOT and I'm also wonder if it's "okay" to just replace the breaker.

I then called another electrician over the phone (haven't had them come out yet) and asked if it was reasonable to just the power from my *panel* in my unit to the car. That would only be 80 ft, but he expressed concern over my 70A breaker. That said, he thinks it might be possible to do a slow 20A breaker. I do have air conditioning in this 650 sq ft unit.

So what's the deal here? Why is it that one guy is willing to upgrade the breaker but then wants to run the 400 ft wiring run, while the other guy is willing to run from the panel but is concerned about the amount of power I have available? What does you all think the best way to go is? Try to get power from my panel? Swallow the cost of a 400 ft run? Is it even safe to upgrade my breaker or to tap off my panel??

For reference, here's my breaker panel:

IMG_4151.jpeg
 
Last edited:
Do you need more than what an ordinary outlet could deliver?

You mean like the 3mi/hr 110V trickle charge? I suppose I could get away with it since my commute is short, but I'd prefer to have a bit more. My thinking is that if I'm going through the expense of running new cables, I would like the idea of coming to a 80% charged car every time I get in.
 

Tam

Well-Known Member
Nov 25, 2012
10,762
9,800
Visalia, CA
....Why is it that one guy is willing to upgrade the breaker but then wants to run the 400 ft wiring run, while the other guy is willing to run from the meter but is concerned about the amount of power I have available?...

I am all confused about how your electrical runs currently.

This is what I assume:

Meter with 70A main breaker that is 400' from parking space->home-main-panel that is 80' from parking space.

Are these options offered to you by electricians:

1) Meter upgraded to 100A main breaker-> then run 400' from there to the parking space without going through the home 70A main panel?

2) Meter with 70A main breaker->to home-main-panel ->new 20A breaker slot and run the wires 80' to parking space.

In general, an electrician needs to worry about how much electricity your whole home would use from A/C to EV charger. If they are not concerned, then there might be electrical fires.

There are different options to deal with your situation so each electrician may offer a different approach and different price.

Electrical upgrades are expensive. If you can afford it, I would go for 100A or even 200A upgrade. It's safer. That could get your EV to charge 30A or more on 240V outlet.

If not, stay the same with your current 70A system and limit your EV charging to 20A 240V outlet.
 
I am all confused about how your electrical runs currently.

This is what I assume:

Meter with 70A main breaker that is 400' from parking space->home-main-panel that is 80' from parking space.

Are these options offered to you by electricians:

1) Meter upgraded to 100A main breaker-> then run 400' from there to the parking space without going through the home 70A main panel?

2) Meter with 70A main breaker->to home-main-panel ->new 20A breaker slot and run the wires 80' to parking space.

In general, an electrician needs to worry about how much electricity your whole home would use from A/C to EV charger. If they are not concerned, then there might be electrical fires.

There are different options to deal with your situation so each electrician may offer a different approach and different price.

Electrical upgrades are expensive. If you can afford it, I would go for 100A or even 200A upgrade. It's safer. That could get your EV to charge 30A or more on 240V outlet.

If not, stay the same with your current 70A system and limit your EV charging to 20A 240V outlet.

You understand the situation correctly. (I had a small typo in the section you quoted which I just fixed.)

Yeah, I'm also concerned about load too. The last thing I want is to have my main breaker trip and for me to lose power to my entire unit because I turned my AC on. Since my main breaker is behind a gate that I don't have a key to, that would be Very Bad. I need the electricians to be able to make sure that this does NOT happen.

Here's my idea scenario, which might not be possible: Upgrade the breaker to 100A, and then run the new circuit from my panel (in my unit which is only 80 ft away) to the parking space. That way I get good L2 charging. However, my *assumption* (take it for what it is) is that the wiring that goes to my unit is NOT good enough to carry 100A service.

So then, it sounds like if I upgrade the main breaker to 100A, then I would have to make that 400 ft run all the way from the breaker to the parking space. But I'm also skeptical that it's "just" a matter of replacing the main breaker. How can they make sure that the 100A doesn't go to my unit's breaker panel, given that the wiring might not be up to snuff (my assumption)?

Also, I would be satisfied with a 20A/240V line if it means I can just run from my unit's breaker panel to the parking space. I'm just scared that even this is cutting it close.

Just to throw a number out of my current electrical use. My power bill indicate an average of 1300 kWh per month or about 1 kW consistently.
 

Tam

Well-Known Member
Nov 25, 2012
10,762
9,800
Visalia, CA
...the wiring that goes to my unit is NOT good enough to carry 100A service...

Correct! The wiring now is for 70A from the meter to your home panel. If you upgrade to 100A to go to your home panel, you'll need new wiring. The wiring and the labor is quite expensive.

I thought the electrician would upgrade the main breaker at the meter to 100A then keep the existing 70A system intact and add another 30A 240V 400' wires separately to your parking space with its own shut-off box over there.


...Also, I would be satisfied with a 20A/240V line if it means I can just run from my unit's breaker panel to the parking space. I'm just scared that even this is cutting it close...

I think your A/C runs 30A 240V so you still have the rest of 70A for other things. But to be safe, you should run 80' from the home panel to your parking space for 20A 240V.
 
Correct! The wiring now is for 70A from the meter to your home panel. If you upgrade to 100A to go to your home panel, you'll need new wiring. The wiring and the labor is quite expensive.

I thought the electrician would upgrade the main breaker at the meter to 100A then keep the existing 70A system intact and add another 30A 240V 400' wires separately to your parking space with its own shut-off box over there.




I think your A/C runs 30A 240V so you still have the rest of 70A for other things. But to be safe, you should run 80' from the home panel to your parking space for 20A 240V.

That's the thing that's a little fishy about upgrading my main breaker to 100A... even if the Tesla has its own separate path, how does he make sure that my unit doesn't accidentally pull that 100A and burn up the 70A wire?

I also think you're right about the A/C running 30A. In my picture, it has a double pole breaker at 30A. I know nothing else about the A/C unit, so I'll have to assume worst-case.

I also just noticed that my breaker #15 is a 20A marked as "spare". I assume that means there's nothing on it. I guess that would suggest that we can replace it with a double pole breaker also at 20A and that it should be "safe" to have a 20A L2 charger circuit on it... right? At the least, that gives me more confidence since I don't think "they" (whoever "they" were) would have put a 20A breaker there if it would be unsafe to use.

I think I'd go with that path then. It's not as sexy as having a higher power circuit, but I can live with 15mi/hr charging.
 
That's the thing that's a little fishy about upgrading my main breaker to 100A... even if the Tesla has its own separate path, how does he make sure that my unit doesn't accidentally pull that 100A and burn up the 70A wire?
He'd have to add a 70a breaker somewhere to protect that wire. For that matter he'd have to add a smaller breaker for the run to the car (40, 50, or 60a depending) to protect THAT wire and outlet. I expect he would be adding a small load center near your meter to hold those. You might want to look into into a DCC-10 Avoids Major Home Electrical Upgrades for an EV Charging Installation . It would be installed at your current panel in your unit, and monitors your power usage. If you are in danger of going over your 70a feed, it cuts the car charging off.

However, if a 240v 20a charging circuit is safe, I'd save the money and just do that.
 
Last edited:
He'd have to add a 70a breaker somewhere to protect that wire. For that matter he'd have to add a smaller breaker for the run to the car (40, 50, or 60a depending) to protect THAT wire and outlet. I expect he would be adding a small load center near your meter to hold those. You might want to look into into a DCC-10 Avoids Major Home Electrical Upgrades for an EV Charging Installation . It would be installed at your current panel in your unit, and monitors your power usage. If you are in danger of going over your 70a feed, it cuts the car charging off.

However, if a 240v 20a charging circuit is safe, I'd save the money and just do that.


Ah yes, I’ve been looking at the DCC units! I might bring that up to the electrician that’s offering to do a run from inside my unit.


Your new 20A 240V outlet should be "NEMA 6-20" and Tesla does sell that pigtail for your portable connector for $35.

6-20_individual_1104934-00-B_0.png
NEMA6-20_1104934-00-B_1.png

I’m actually looking into getting the Tesla Wall Connector even if I can only do 20A. My understanding is that it will let me take advantage of the L2 charger tax credits and my power company rebates, which would actually make my installation cheaper overall!
 

Tam

Well-Known Member
Nov 25, 2012
10,762
9,800
Visalia, CA
I’m actually looking into getting the Tesla Wall Connector even if I can only do 20A. My understanding is that it will let me take advantage of the L2 charger tax credits and my power company rebates, which would actually make my installation cheaper overall!

Sure. That's totally sensible since you'll have an electrician with you already and the tax credits that I didn't think of!
 
  • Like
Reactions: MetricExpanse

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
2,183
2,467
Massachusetts
Here's an idea that might work for you...

Get a switchbox that allows either your dryer or your charger to get power, and mount it right next to your power panel. That's a 24 amp continuous 240 volt charge for $139, I assume MUCH cheaper and smaller than the DCC, albeit a little more work on a per-charge basis. I'd assume you'd keep it set to 'charger' mode unless you were actually drying clothes.


Note: I couldn't find frequency-of-switching data allowed for that switch, and I imagine you might want one with a front mounted actuator. It might be worth a chat with the electrician.
 
Here's an idea that might work for you...

Get a switchbox that allows either your dryer or your charger to get power, and mount it right next to your power panel. That's a 24 amp continuous 240 volt charge for $139, I assume MUCH cheaper and smaller than the DCC, albeit a little more work on a per-charge basis. I'd assume you'd keep it set to 'charger' mode unless you were actually drying clothes.


Note: I couldn't find frequency-of-switching data allowed for that switch, and I imagine you might want one with a front mounted actuator. It might be worth a chat with the electrician.

That's a really good idea. Now you have me wondering if I could get something like that which is controlled by WiFi. I have a Nest thermostat, so it wouldn't be hard to write some software that checks the Nest website and determines if the Nest is likely to run the AC and then remotely toggle the circuit.

The problem would be getting an electrician to agree to installing it and probably getting the electrical inspector to be "okay" with one of my circuits being on a such a thing... is there such a thing as a remote control breaker that would pass permitting?
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
2,183
2,467
Massachusetts
Sorry, yeah, should have reread your original post. AC will be a hard one to share with, and an electrician/inspector would very likely have concerns.

I'm sure there are remote controlled breakers, and if you really wanted, I bet that your AC is driven by a simple 24 volt input or two. It would be trivial to take that input and get it to enable the power for the AC, although that would not be a 'gentle, planned' shutdown of the Tesla charger, it doesn't need to be.

I can find several pretty chunky relays that can do exactly the switching you want, even driven by 24 volts, but I'm sure the NEC wouldn't be cool with such a solution.

Here's one that might do fit the bill, but I wonder greatly about the rules for putting 24V in the same neighborhood as your 70 amp service: Details - Functional Devices, Inc. Also not clear it'll handle the startup current of your AC.
 
Last edited:
  • Like
Reactions: MetricExpanse
Sorry, yeah, should have reread your original post. AC will be a hard one to share with, and an electrician/inspector would very likely have concerns.

I'm sure there are remote controlled breakers, and if you really wanted, I bet that your AC is driven by a simple 24 volt input or two. It would be trivial to take that input and get it to enable the power for the AC, although that would not be a 'gentle, planned' shutdown of the Tesla charger, it doesn't need to be.

I can find several pretty chunky relays that can do exactly the switching you want, even driven by 24 volts, but I'm sure the NEC wouldn't be cool with such a solution.

Here's one that might do fit the bill, but I wonder greatly about the rules for putting 24V in the same neighborhood as your 70 amp service: Details - Functional Devices, Inc. Also not clear it'll handle the startup current of your AC.

Yeah, now that I think about it, I could also set up something that monitors the Nest thermostat and then sends a command to my Tesla to stop charging via Tesla's API if the sensed temperature is close to the AC trigger temperature. That would be a "soft" solution. The main reason to have a "hard" solution (like that relay) is so that I could "prove" to an inspector that it's not possible for the AC to run at the same time as the EV charging.

But, as you're suggesting, I'd guess that NEC would not sanction either of those approaches, right? I think they'd take one look at my overloaded breaker panel and give me a red stamp, if I could even get an electrician to do it. It looks like 20A is probably all I can get unless I want to pony up for one of those DCC-9 boxes (which I guess somehow makes it acceptable to NEC?).
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
2,183
2,467
Massachusetts
I'd guess that NEC would not sanction either of those approaches, right? I think they'd take one look at my overloaded breaker panel and give me a red stamp, if I could even get an electrician to do it.

Not so sure about that. In both the mechanical switch and the relay case, I'd expect to be reusing that same single circuit breaker, split into two outbound paths at the relay/switch. The key would be getting a relay that is acceptable to the electrical inspector and electrician. I >think< that if there's space in the box you wouldn't have to mount it separately, but I'm still really unhappy about potentially mingling a low-voltage ~24v signal with your panel voltages. Also concerned that you won't easily find an inductance-load rated relay of that size for residential use. I'm absolutely sure they exist in an industrial setting.

Might not hurt to actually do a load calculation on that panel. I also assume someone has verified that the feeder for the panel is only like 4 awg romex.
 
  • Like
Reactions: MetricExpanse
Not so sure about that. In both the mechanical switch and the relay case, I'd expect to be reusing that same single circuit breaker, split into two outbound paths at the relay/switch. The key would be getting a relay that is acceptable to the electrical inspector and electrician. I >think< that if there's space in the box you wouldn't have to mount it separately, but I'm still really unhappy about potentially mingling a low-voltage ~24v signal with your panel voltages. Also concerned that you won't easily find an inductance-load rated relay of that size for residential use. I'm absolutely sure they exist in an industrial setting.

Might not hurt to actually do a load calculation on that panel. I also assume someone has verified that the feeder for the panel is only like 4 awg romex.

OH I SEE!! Sharing the same 30A circuit, huh? You know, I'll ask my electrician to see if he's game. But you're probably right that there no decent residential relay I can use. And I see your concern about mingling panel voltage with 24V... it does seem unsafe if I ever have to fiddle with the thermostat and stuff.

I went ahead and actually did a load calc over the phone with the electrician who's offering to run the cable from my unit. Apparently whatever formula he used would allow me to have 50A (!!), but then he said that he feels safer with 20A or maaaybe 30A. As of now, 20A is where my expectations are. I've called them over to do an on-site inspection so I guess we'll see what they say.

As far as verifying the feeder... no one's actually verified it by actually looking at the cable. I have no idea what's in there.
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
2,183
2,467
Massachusetts
Ain't no way you have 50 amps of excess capacity on that panel. You need to assume that at least the refrigerator, AC, and AC Fan will all run at the same time. Now >maybe< your AC only draws 20 amps(AC's are notorious for needing extra-large breakers to start), and maybe your fan only uses like 7 amps, and your refrigerator uses 10 of that 15 amp circuit continuously-ish). Right there I see 37 amps, assuming you are sitting in the dark, with the TV off, and so on. I'd agree that 20 is probably fine, 30 would probably be over the edge. The good news is that even if you go too close to the edge, you can either tell the HPWC not to allow more than the lower(probably 16 amps delivered) value, or if you can dial it back in the car to 20(rather than the 24 that a 30 amp circuit would allow). The minor potential disadvantage of letting the car control it is what happens when some stranger's tesla connects on a Friday afternoon when you've gone away for the weekend, pops your main breaker and drives away. You come home to a hot condo, dead fish, and spoiled food in your refrigerator.

There are two different methods for load calculation, and apparently you are allowed to choose whichever one you like(usually the one that gives more capacity!)

I'd be popping that indoor cover off to have a look at the feeder wires. It looks like there's quite a few inches of empty space above the breakers, so you might be able to see the wire specs there.... just don't touch anything! Its more than likely fed by romex, so you won't be able to see the sheath(and therefore conductor size) anyway. If you can get access to the place where the 70 amp breaker is, its probably got a virtual medusa of romex heading out the top of the panel, and its probably all the same size.
 
Ain't no way you have 50 amps of excess capacity on that panel. You need to assume that at least the refrigerator, AC, and AC Fan will all run at the same time. Now >maybe< your AC only draws 20 amps(AC's are notorious for needing extra-large breakers to start), and maybe your fan only uses like 7 amps, and your refrigerator uses 10 of that 15 amp circuit continuously-ish). Right there I see 37 amps, assuming you are sitting in the dark, with the TV off, and so on. I'd agree that 20 is probably fine, 30 would probably be over the edge. The good news is that even if you go too close to the edge, you can either tell the HPWC not to allow more than the lower(probably 16 amps delivered) value, or if you can dial it back in the car to 20(rather than the 24 that a 30 amp circuit would allow). The minor potential disadvantage of letting the car control it is what happens when some stranger's tesla connects on a Friday afternoon when you've gone away for the weekend, pops your main breaker and drives away. You come home to a hot condo, dead fish, and spoiled food in your refrigerator.

There are two different methods for load calculation, and apparently you are allowed to choose whichever one you like(usually the one that gives more capacity!)

I'd be popping that indoor cover off to have a look at the feeder wires. It looks like there's quite a few inches of empty space above the breakers, so you might be able to see the wire specs there.... just don't touch anything! Its more than likely fed by romex, so you won't be able to see the sheath(and therefore conductor size) anyway. If you can get access to the place where the 70 amp breaker is, its probably got a virtual medusa of romex heading out the top of the panel, and its probably all the same size.

Hah, yeah I think I'll install a 30A circuit if the electrician is willing to do so, and then just soft-limit it to 20A in the HPWC. If I luck out and it's actually fine to use 30A, then great! As for someone coming and stealing my power... I might just have to get in the habit of flicking the breaker for it when I leave so that it's de-energized. I wish Tesla had a way to let you lock it to a car or something! Get to it, Elon!

I did not know about the two methods of load calculation! I am a curious person, so I'd love if you have any reading material on it. :)

Are you saying I could remove those white screws to see what's feeding the panel? Is it safe? I've never opened up my load center before lol.

Unfortunately, I don't normally have access to the main breaker over by the meter; I have to ask for it to be unlocked by the janitorial service.
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top