Charging with 30 amps

Kurt Carlson

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I live in a condo and was thinking of charging the truck with a 30 amp 240 volt outlet (not enough power in my breaker panel for more and condo association sucks to deal with). Someone was talking to me about this product (evenflow energy router) the other day, anyone have any opinions? How many miles will the CT charge over night on 30 amps?

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ajdelange

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First off 30A @ 240V = 7.2 kW. The charger in the car is about 90% efficient meaning about 6.5 kW will wind up going to the battery. In one hour that means 6.5 kWh. Now it gets a little tricky as we don't know how much the car needs to go a mile. That depends both on the car and how you drive it. Assume that the number will be 0.450 kWh/mi. It's probably going to be something like that. Then you would get 6.5/0.45 = 14.44 miles per hour or 144.4 miles in a 10 hour period. That should be enough for most people.

As to the Evenflow device - EVSE must be the only thing connected to its branch circuit. Here you would have the Evenflow connected to a branch circuit with two devices (the washer/dryer and the EVSE) connected to the Evenflow. Does that satisfy 625. 41 through the load shedding provisions of 625.42? I have questions and your local inspector might too. Contact an electrician. Presumably you will be using one for the installation rather than doing it yourself. He should know how your local authority regards such a device. It is their opinion which counts in the last analysis.

There is one other thing that needs to be considered here and that is that if the Evenflow is connected to a 30 amp breaker it must be derated to 24 amps (0.8*30) in order to comply with the code. Thus would mean 11.5 mi added range per hour instead of 14.4 and 115 miles in 10 hrs. That should still be enough. If you install a 30 amp plug at the output of the Evenflow and charge with the UMC supplied with the CT using the correct adapter for a 30A plug the UMC will take care of this derating automatically. An alternative is to install a 50A breaker in the main panel and to hard wire a wall charger to the Evenflow output. The wall charger would be set for 50A feed and thus limit the vehicle to drawing 40A. This would give you an extra 16 A charging relative to what you can get from a 30A breaker feeding the Evenflow. This would give you 240*50*.8*.9/450 = 19.2 miles added range per hour. The question now is as to whether your panel can support the removal of a 30A breaker and replacement of it with a 50A breaker. The extra load is actually only 10A and the liklihood is, therefore, that it very well can. Again, a local electrician who knows the inspectors will have a good idea as to whether this would be acceptable.
 
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Kurt Carlson

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That is a tremendous amount of information, thanks! And like any truly good answer, it creasted more questions than it answered!

If the inspector has a problem with the breaker, couldn't the electrician just put a single breaker down stream from the evenflow before it gets to the charging station? Although maybe that'd be a pain for the electrician?

https://www.homedepot.com/p/Eaton-BR-70-Amp-2-Space-4-Circuit-Outdoor-Main-Lug-Loadcenter-with-Cover-BR24L70RP/100128514?MERCH=REC-_-pipinstock-_-100196368-_-100128514-_-N

Regarding your last point, that sounds really interesting, wouldn't that mean I'm powering my dryer with a 50Amp breaker? Can you do that? It won't fry the dryer?
 

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I would look at other things before evenflow. Why do you say you have 30 Amp? Did the electrician tell you that you can only add in a 30 Amp breaker max? What's the total AMP going to your panel? Do you have an electric oven or gas? What other >20 Amp breakers are in your panel currently?
 

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That is a tremendous amount of information, thanks!
Yes, I'm afraid it isn't simple and it is also all relatively new to the inspecting authorities and to electricians installing this stuff.

If the inspector has a problem with the breaker, couldn't the electrician just put a single breaker down stream from the evenflow before it gets to the charging station? Although maybe that'd be a pain for the electrician?
That would be perfectly logical in that were breakers installed that would effectively make the combination a sub panel. But to some inspectors logic doesn't matter if it's not in the book.

I went to Evenflow's site and found a FAQ for electricians where some of my questions are addressed. They do mention that the equipment is "listed" and also specifically mention 625.42. This suggests that their basic installation without supplemental breakers is sufficient but they also specifically mention that the local inspector has the last word and suggest that your electrician take their literature with him when he goes to pull the permit.


Regarding your last point, that sounds really interesting, wouldn't that mean I'm powering my dryer with a 50Amp breaker? Can you do that? It won't fry the dryer?
That's not a problem. The load draws whatever current it needs. The breaker is there to protect the wire. Thus if you install a 50 A breaker you will have to pull No. 6 from the panel to the Evenflow and from the Evenflow to each of the EVSE and the dryer even though the drier be a 30 A load. Clearly if the dryer is in the garage near the electric panel this wouldn't present much difficulty but if it is 2 floors up in a laundry room it would. In the latter case you might get by with a supplemental 30A breaker for the No. 10 wiring that's already there. Another thing to discuss with the electrician.
 
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Kurt Carlson

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I would look at other things before evenflow. Why do you say you have 30 Amp? Did the electrician tell you that you can only add in a 30 Amp breaker max? What's the total AMP going to your panel? Do you have an electric oven or gas? What other >20 Amp breakers are in your panel currently?
I have a 100 amp panel and it looks like it's already full. There is a 30 amp breaker for the dryer so that was why i was asking. Gas stove. All the 20 amp breakers are 120 volts not 240. I do have a 15 amp breaker for the AC but that would be pretty slow to charge I bet.
 
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Kurt Carlson

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Yes, I'm afraid it isn't simple and it is also all relatively new to the inspecting authorities and to electricians installing this stuff.

That would be perfectly logical in that were breakers installed that would effectively make the combination a sub panel. But to some inspectors logic doesn't matter if it's not in the book.

I went to Evenflow's site and found a FAQ for electricians where some of my questions are addressed. They do mention that the equipment is "listed" and also specifically mention 625.42. This suggests that their basic installation without supplemental breakers is sufficient but they also specifically mention that the local inspector has the last word and suggest that your electrician take their literature with him when he goes to pull the permit.


That's not a problem. The load draws whatever current it needs. The breaker is there to protect the wire. Thus if you install a 50 A breaker you will have to pull No. 6 from the panel to the Evenflow and from the Evenflow to each of the EVSE and the dryer even though the drier be a 30 A load. Clearly if the dryer is in the garage near the electric panel this wouldn't present much difficulty but if it is 2 floors up in a laundry room it would. In the latter case you might get by with a supplemental 30A breaker for the No. 10 wiring that's already there. Another thing to discuss with the electrician.

Looks like I have some questions for the electrician, thanks. If I could swap out the 30 amp breaker for 50 amp that would be great! I'll reach out to the electrical inspector in town and see what he says also.
 

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There are things you can do such as take out 4 fat breakers and replace them with 4 slim style leaving two fat slots for a 2 pole fat style but the panel must have stabs that allow this. I think the bigger issue would be getting approval for an additional 24 A (30 A breaker) amp load. Thus it appears the load shedding approach may be the best one for you. You might get approval for the 50 A breaker as the extra load, with the shedding, is only 10 A but again that would be up to the inspector. The code itself allows more installed breakers in a panel than the normal load calculation algorithm permits if you can show a year's worth of actual utilization data. The path of least resistance appears to be the Evenflow with a 30 A outlet or HPWC set for a 30 A breaker.
 

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I guess I should add that though I can charge at 17 kW I only in fact charge at 5 (20A) and that works out just fine for me. I don't care if it takes 12 hours or more to recharge. The reason I do this is to dodge the power company's "maximum 30 minute demand" charges which allows them to bill me for electricity I don't use on the basis that some day I might use it and they had to invest in equipment to supply it even though they didn't. Don't ask.
 

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Tesla has charts on their site for the max miles of range per hour of chart on their website for the wall connector and mobile chargers. It's based on circuit breaker amperage and maximum output of amps. You'll see each model is different, but at least looking at the current largest vehicle (Model X) will give you a ballpark figure for what you can expect, although a bigger vehicle like the Cybertruck will likely get less range per watt (less miles of range per hour charged).

https://www.tesla.com/support/home-charging-installation/wall-connector

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I kicked the Nema 14-50 right off my parents stove at their beach house... now the joke is don't use the stove when our car is charging, but cook the eggs on the M3 battery. Ha!
 
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I guess I should add that though I can charge at 17 kW I only in fact charge at 5 (20A) and that works out just fine for me. I don't care if it takes 12 hours or more to recharge. The reason I do this is to dodge the power company's "maximum 30 minute demand" charges which allows them to bill me for electricity I don't use on the basis that some day I might use it and they had to invest in equipment to supply it even though they didn't. Don't ask.
That's crap, I thought only industrial companies are billed that way, wild! With a Model 3, the 20 amps looks like it would be plenty according to the above chart, might be a bit tight with the CT though. I wonder where the Y will fit in that chart, probably halfway between 3 and S.
 

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Yes, in general it is only industry. But in Virginia, and other states, the utilities have argued that they still have to have to install infrastructure to supply a solar user and size it to meet his peak demand because the sun doesn't shine at night and on cloudy days. Thus solar panel owners on Dominion Energy's net metering tariff are subject to peak demand charges even though no changes are made (other than putting in a net meter) when solar is installed. I can somewhat appreciate their POV. Their electric sales to me have dropped 60% and they are forced to absorb power produced by me that they do not want at a time when they do not need it but they still have to maintain poles, transformers, substations., etc.
 

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So as to rates electric companies employ. Business load characteristics vary greatly from business type to business type. A gas station has very different load pattern than a lumber store. Each has consumption (think volume) which creates variable costs such as fuel cost. They also have varying levels of instantaneous consumption. Instantaneous can mean 5 minute, 15 minute or 30 minute or even hourly depending on the utility.
Fora gas station the load is relatively steady over the day and if the station is open 24 hours, the usage is even more flat. For a lumber store the summer load is dominated by A/C and there is little use over night while they are closed and much less consumption during the winter if heated by gas.
The utility has capital costs and operating costs. Capital costs are associated with the capacity they have to install to serve the customer. Generators, wires and transformers have to be large enough to meet the maximum load when required. Operating costs are more related to consumption like fuel and wear on equipment.
If the utility wants to be fair it cannot charge the same consumption (price per volume) to both customers. The lumber store uses proportionally fewer kWh (volume) per kW (demand) than the gas station. There used to be rates for all kinds of businesses but it is much more equitable if the rates reflect the utility actual cost of doing business.
Residential customers are different they have much more homogeneous load characteristics and so a simple kWh rate is a sufficient proxy if an assumption of load patterns is accurate. But there will be load characteristic outliers who may benefit or not depending on their particular load. Some utilities have chosen to bill residential customers like commercial customers with a capacity (demand) charge and an energy charge.
 

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Thank you, Fabville, for providing the chart. This is consistent with our findings.
We didn't go to the expense of installing a Tesla Wall Connector (although they do look very cool).
Our Gen 1 Mobile Connector cord uses a NEMA 6-50 adapter that plugs into our welder's 40A outlet. The outlet power comes from two 40A circuit breakers in a 50A sub-panel in our barn. Our MS P-85 gets charge rate of 22-23 MPH for routine charging to ~ 80% capacity.
The display on the Tesla's screen indicates it is charging at 30 amps.

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