I’m in the same boat as the OP except I have 100A service. My neighbor is a licensed electrician and he told me the same thing. He said I could install a 14-30 outlet but couldn’t run my stove or clothes dryer when charging. That wouldn’t be a problem because I schedule my charging when those activities are less likely to happen. He said it probably wouldn’t pass a house inspection and I plan on moving in two years so I guess I’ll live with 120v and top it off at a SC for a long trip.
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I live in a condo. The main breaker is only 70A. Now what? [Resolved]
- Thread starter andy92782
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I’m in the same boat as the OP except I have 100A service. My neighbor is a licensed electrician and he told me the same thing. He said I could install a 14-30 outlet but couldn’t run my stove or clothes dryer when charging. That wouldn’t be a problem because I schedule my charging when those activities are less likely to happen. He said it probably wouldn’t pass a house inspection and I plan on moving in two years so I guess I’ll live with 120v and top it off at a SC for a long trip.
Be curious how he plans to do it. And how much they are quoting. Any 240V circuit is so much better than any 120V option.
What would a JuiceBox buy you?
Wall Connector or UMC will do everything the JuiceBox would do.
We have a 100 amp service. Electric stove and Dryer. Electrician added a stove plug to the garage for the Juice box. All within code. We are adding a 20 amp 240 line for outside parking for a 16 amp EVSE. Electrician came out, did the calculation and said it was okay but then it’s at Max.
eprosenx
Active Member
Or better yet, if the load calcs would support it you could replace the single 30a 240v breaker with one that was dual 30a 240v. (but yeah, unlikely that the load calcs would support it)
Eaton BR 2-30 Amp 2 Pole BQ (Independent Trip) Quad Circuit Breaker-BQ230230 - The Home Depot
But this is fantasy regardless since the Eaton BR series breakers are not listed or classified for use in a Challenger panel. Even the "special" "CL or CH" series breakers that Eaton makes that are classified for use in competitors panels (by UL rating) are not rated for Challenger panels from what I can tell (it might be mechanically a totally different size or bus rating).
I am very curious if anyone does make tandem 240v (2 pole) breakers for Challenger panels. It would be good to know.
Though again, swapping that panel out with a new one should be quite inexpensive and then you would be able to get new modern breaker options.
eprosenx
Active Member
Are you in a townhome or a detached dwelling? Typically a 100a service is fine for some amount of EV charging as long as you have natural gas for heat / water heating. Note that I often recommend folks get a Wall Connector and wire it up with say a 50a circuit. Then you can crank down how many amps it is allowed to draw using a rotary dial inside the unit in order to stay within what the load calcs say. It has pretty fine granularity (vs. having to switch from a 20a to a 30a to a 50a receptacle with the UMC)
Note that I have never seen a house inspector actually do a full load calculation on the breaker panel. Unless it was obviously massively overloaded I suspect an inspector would not bat an eye at it. (I just was with an inspector last week who inspected a friends new house and I was impressed that he checked the wire gauge into each breaker, but there as no NEC load calc done)
I would get a "Sense Energy Monitor" unit and watch your load over time. You might find that you have a lot more headroom than you think.
I am wondering if the following clause can be made use of in residential load calculations:
I would be inclined to think that my Sense Home Energy Monitor would provide sufficient history data in order to exercise this clause to let you use your limited service capacity to its fullest.
I won't pretend I know how to do load calculations or which breakers are legal in a challenger panel.
To me 20 Amp 240 would be fairly comfortable for most people, without it being annoying.
Google around I see Cutler Hammer mentioned a lot in association with Challenger Panels and Eaton being one and the same as Cutler Hammer?
This Breaker is a 30-30 Quad and listed as Eaton/Cutler-Hammer/Challenger.
Just because some vender lists it as such doesn't make it legal. I think the 20-30 would be safer.
Even if under load calculations.
https://www.amazon.com/br430-Eaton-Cutler-Hammer-Westinghouse-Challenger/dp/B008CRD5QY
eprosenx
Active Member
Ouch. This is a challenging one.
First off, based on the pictures you sent, I think this might be single phase service. The sticker says 120/240v 3 wire service (hot, hot, neutral). That is actually good since it is faster charging than 208v and is more common in residential.
So I am wondering if you could exercise the "tap" rules in the NEC in order to tap off your main 60a feed (between the main service switchgear and your condo unit) into a fused disconnect or small breaker panel next to your car. 60a is really really a tiny amount of power to work with - you would need to determine if you have any capacity available per NEC load calculations. Maybe at best you could do a 20a or 30a 240v receptacle?
The other option might be to install a second meter with a new service dedicated to the car. The challenge I see there is that there is absolutely zero physical space available and also load calculations on the main 600a feed could be a concern. I wonder if it is already maxed?
There might be a creative solution available here, but unfortunately that building could be looking at big money to upgrade / replace the electrical switch gear. The only creative option I am seeing is that the far right meter pack only has two meters vs. four. Depending on what is behind that soffit, you might be able to upgrade that to a 4-pack and get a dedicated meter for your car, but yeah, that sounds like a long shot.
Where do you live? I know California has laws requiring accommodation for EV charging right?
The building really needs to be planning for the future that involves EV's.
eprosenx
Active Member
Oh gosh, you might be right. Challenger may have become (or was just a brand name of?) Cutler Hammer which became Eaton. Eaton makes the BR style breakers which are "listed" to work in a number of the panels from various folks they purchased. But then they further make the CL series of breakers which are "classified" to work even in a number of other manufacturers panels (i.e. 3rd party panels but that are approved by UL even though the manufacturer does not "list" them).
So yeah, the BR breakers we have been linking to may just work in that panel and be 100% code compliant.
Also, after further research, it is unclear to me whether Challenger panels are a safety issue or not. I find no definitive source on the Internet about this. It sounds like maybe only a subset of panels / breakers (or maybe actually only breakers themselves) had issues. That Challenger panel might be 100% fine as-is and it would be easy to add a tandem breaker as linked to of either 15, 20, or 30 amp varieties depending on what is supported per your load calculations.
Depending on your driving habits, a single 20a 240v breaker may be sufficient as long as your climate is not too cold such that heating is needed before the battery can charge (I am curious how the Tesla would handle battery heating if it only has 20a @ 240v available - that might not be enough juice to heat the battery to get it to a temp where it can charge).
eprosenx
Active Member
Would there never be a time (say if only charging on 120v 15a/12a) that the thermal loss of the battery would outstrip the heating ability and so the battery would never achieve a temperature at which it would actually start charging it?
What would you (or anyone) say is the minimum circuit you would need to get things charging (in a reasonable amount of time say under 1hr) if say the car was left overnight at 0 F? For some of us northerners, I think that is more critical than miles/hr charge rate once you get past say 70% charge overnight (e.g. 200 miles in 10 hours - ish).
Other considerations, which I think you and some folks have is charging as much as possible during off-peak metering.
This is a good question, and I can answer @mswlogo too. My answer was responding to the specific case listed above, with a 240V 20A circuit. That would be 240V at 16A to the car for about 3.8kW. The battery heating in the S and X has a total max power of 6kW, but can run variable power I'm pretty sure, or can supplement a little from the battery. Now that the Model 3 uses a different form of heating using the motor windings, I haven't heard what kind of power level of heating that can do.
With 3.8 kW of input power, I'm pretty sure that is high enough that it can eventually get the battery to charging temperature and keep it there, even in very cold outside temperatures, like below 0 Fahrenheit. But that can be warming for an hour or two before charging begins, so you lose some of your overnight charging time. If you're up around 5 or 6 kW, I think I will be able to charge in any temperature.
So for your specific question, the 120V 15A (supplying 12A) is only about 1.4kW, and I have heard from multiple people where it was just too cold, and the car drew energy all night trying to warm, but it was lost to the air too fast and couldn't warm up, and it wouldn't charge anything, and the car lost a few miles.
eladts
Member
You should never put a NEMA 14-50 on a 20A or a 30A circuit. For a 20A circuit, the appropriate socket is NEMA 6-20. For 30A it is either NEMA 14-30, NEMA 10-30 (obsolete) or NEMA 6-30 (no native adapter). Tesla UMC adapters are available for NEMA 6-20, NEMA 10-30 and NEMA 14-30.
eprosenx
Active Member
To be pedantic here, I think putting a single 14-50 receptacle on a 20a circuit is technically allowed as long as your intended load does not exceed the ampacity of that circuit, but regardless, it is a bad idea. I only would ever recommend putting a 40 or 50a circuit on a 14-50 (and the 40a only in very limited situations).
As stated above, the right thing is to put a 6-15, a 6-20, or a 14-30 on those lower amperage circuits so the receptacle and the circuit are directly matched.
OP here. I’ve had a chance to calm down a bit. I think this DCC energy management box is my possible salvation.
DCC-9-30A | Energy Management System for Electric Vehicle, Splitter Box 120/240-208V, 30A breaker, Max 125A
A 30A charging breaker is recommended when used on a 70A main breaker. 240V/30A with the UMC2 cable would be perfectly acceptable to me. Install it with a 14-30 socket and I’d be good to go.
I contacted the building department for my city and asked them if they’d sign off on one of these. The guy on the phone said “Hmm, that sounds pretty cool.” They’re going to review the specs and let me know. I plan on calling their office every day until I get an answer. If they give me the thumbs up, I’m in.
I would not call them every day if you want that solution. You don't want to be a nuisance, it would just be easy for them to say no.
If you are planning on ordering for delivery before the end of the year you might let them know you really need an answer soon if your planning on those expiring tax breaks.
I might be mixing up threads but didn't you say you had an Electrician that said he could add a 240V 30Amp, proper?
Now that you started this path, there might be no turning back.
I'm not sure what you mean by "30A charging breaker is recommended when used on a 70A main breaker". Say what?
There is no recommended amp breaker based on main breaker size. Other than you can't exceed it. It depends on a bunch of things.
P.S. Adding that device will probably cost way more than a new panel. You'd be surprised how little capacity you use on a panel. Or how close you ever get to peak. I have 100% monitoring. Peak usage over the last year was 6000 watts (and that was for all of 5 minutes). Normal peak is 4000 watts. About 25% of my 100 Amp. That is with a Pool and HVAC (both Pool and HVAC are state of the art though, pool uses 80 watts 24/7 during summer months
). The 30 Amp EV puts another 6000 watts on top of that bringing me to a whopping 50% peak of capacity. I could get by with 70A easy.
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Since I started this I discovered a document on my city’s website for the planning of residential installations of L2 EV chargers. A main breaker of at least 100A is required for them to approve anything.
The manufacturer of the DCC energy management box suggests a 30A maximum EV charging circuit when used on a 70A main.
NathanielHrnblwr
Member
That was before they saw the DCC device. They may be willing to sign off on the 70a with the DCC.
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