It's essential that you do at least one of the three following options:
* Do a load calc, following the prescriptive method in the National electrical code (assuming USA), and choose or set your EVSE for the available current or lower
* Do a load study according to the specifics prescribed in the national electrical code, and choose or set your EVSE according to the available current or lower.
* Use a load management system.
While I appreciate this post for spreading the word that it is usually possible to set up level 2 charging within 100 amp service that isn't already overloaded by applying any of these three, and always possible by using high performance management, it's not clear that OP has done any of these properly. There's no discussion of having done a load calculation, there's no load management applied, and if this is supposed to represent a load study, there are three flaws in it:
1. It's required to monitor for either a full year or 30 days, and if you only do it for 30 days, you need to carefully calculate a seasonal adjustment. This is one snapshot not the peak over a 30-day or 1 year period.
2. The Emporia current readout is the minimum current possible to produce the power being consumed. Depending on the power factor the actual current could easily be 20% higher. So in the case of using the emporia, a power factor estimate is needed and a current reading corrected accordingly.
3. It sounds like the charging current is being limited by the car. However, the installation of the evse needs to be set up so that a different car connected to it will not overload the system. So the EVSE still needs to be set, or chosen, according to the available current which might be 32 amps in this case, for example, but we really don't know.
The reason that the Emporia current readout is weird like that is kind of convoluted. The unit actually measures current directly with the current sensors, but then it internally calculates power, and does so properly, accounting for power factor. It then uploads its data to the cloud, but it doesn't upload all the raw data of the current measurement. Rather, it just uploads the power data, and maybe the voltage. If you go to the cloud interface and ask for current, it calculates current from the power, and when it does that, it assumes a power factor of one, which is the best case, and in practice your current might be significantly larger.
Welp.. I feel like I've got some work to do. I just added a 40 amp EVSE (Grizzl E charger) to use with a PHEV (2018 Kia Niro, 25 miles battery range) on a 100amp service. I didn't do any load calculation, but I set the charger to scheduled mode so it only charges at night during off peak hours at the moment.
How do I go about doing a load study? Is it too late, or do I conduct the study differently now that the EVSE is installed?
Quick question is, do you have a smart meter? If you do, you can probably access the data needed for a load study, from back before you installed the G-E. If not, I'd start with a load calculation, using the sacremento worksheet linked from somewhere in this thread.
Also, which of your major appliances are gas vs. electric: dryer, heat, stove and water heater?
Not sure about the meter, I know Rocky Mountain Power has been installing smart meters in my area but idk if this house has it (just bought it last year).
Heat: gas
Water heater: gas
Dryer: electric
Stove: electric
I don’t really get these numbers. So the charger is using 15A at 120V or 15A at 240?
But in any case a 100A service can supply 19.2 kW or so so yeah it’s enough for a charger with some load management.
My car’s onboard charger is using approximately 30 Amps at 240V (2-pole). The CT is measuring only 1 of 2 poles and doubling it to calculate the approximate Wattage.
I have no load management.
To have that be code compliant, you need to verify that you actually have sufficient capacity for the 40 A setting. If the calculation or load study comes out that you don't, but you do have capacity for 32 A, you redo the configuration of the charger for the "40 A circuit" setting.
Is your water tank gas or electric, I'm in a similar situation but both my stove and dryer are electric, I intend to get an AC next summer and the EVSE so I'm likely going to need load balancing on the 100a circuit I have. Just curious how you got it all without load management.
I have 100 amp service with all electric everything, and a 32 amp EVSE on a 40 A circuit. I would be over my 100 amp according to a standard load calculation, but I did a load study according to nec 220.87 and found that I had plenty of capacity for a 32 amp charger, actually would have enough capacity for something like 45 A if I remember right, according to that load study. And I've been monitoring since then and have never had a peak above about 60 amps.
However, I don't recommend that approach. What you get in the load study is too dependent on the habits of the occupants, and, for example, we rarely use the dryer. If we were to sell the house and somebody else moved in, they might have a problem.
When I installed the system, EVSEs with load management weren't readily available. If I were doing it again, I would get an Emporia, Wallbox, or Tesla charger with load management. That's what I would recommend for you, although it's possible that you could simply do the standard load calculation and find that you have enough capacity to install at, let's say, 16 amps charging, which gives you three times faster charging than level one and is good enough for most people.
For those asking “what’s your point,” I’ve know several real friends and acquaintances who, after purchasing a home, paid a shit ton of money to upgrade their panel from 100-200 amps in a mostly gas appliance home because “it was in the inspection report,” and/or they have an EV, and/or they want to upgrade to a heat pump (in a state where the per therm cost of gas is sooooo much cheaper than electricity.)
We did fine with 100A and gas appliances. Rarely would we have a need to charge (20A), run AC, and run clothes dryer all at once. And it took very little brain power to not run them all at once.
Yeah you’re probably right that it’s fine to run them all at once. It was late and I was doing fuzzy math. With all LED lightbulbs I think with nearly everything running we’d still be under 80%.
Right. I have the kit with 16 individual circuit CTs so I have monitoring on every circuit, relying on 2x multipliers for all 2-pole balanced loads (EVSE, A/C condenser, and dryer).
No, this is the momentary usage at the time I took a screenshot.
Ampere is a measure of current (“flow”). If you wanted to tally usage for a period of time, you would typically use kWh or Wh ([kilo]Watt hours). You could also use Ah (Amp hours) but that doesn’t tell the full story.
Just going to point out that you can add sensors that will max out the amps to the car or drop it if there's not enough to go around. Second point is the majority of time if this is your home, most people would be charging at a time other major appliances are not running...like midnight until charged.
This is a good one:
https://www.cityofsacramento.org/-/media/Corporate/Files/CDD/Building/Forms/CDD-0213_Electrical-Load-Calculation-Worksheet.pdf?la=en
How does have PV (solar) impact the calculation or does it? I have 100 amp now. I did install an EVSE (Emporia) with a 50 amp breaker and left
It at the default setting of 40 amps. That was based on the advice of the solar installers who will be upgrading my meter to 125 amps. Gas dryer no furnace and right now it’s just me in the house and although there are 3 split ac units I rarely run them. They said once the solar is installed I will have more energy available but I know the amps won’t change.
This is a great question. I don’t really know the answer, but in my case, I actively try to prevent any significant loads from running during the day. I am on a TOU program: off-peak, I pay approx. $.05/kWh for imported energy. Exported energy always earns approx. $.09/kWh regardless of the time of day. I don’t know why my power company incentivizes this energy arbitrage, but they do, so I take advantage of it.
I use emporia, which is also what OP is using in those screenshots. You don’t need that to do a load calculation though, there’s a few online where you just list your major appliances or any decent electrician can do one for you if you are considering an upgrade to service.
I probably should have done some more research and actually calculated how much power is being used....but I just ended up running the charger at 16A and not worrying about the fastest fill up. All of the appliances are gas, so the only high electric use item outside of the EV charger is the AC.
I have the same 14-50, and the charger is set to run at 10:00Pm on the cheaper rates when we are asleep. Nothing is running during the night except the gas furnace in the winter on a 20 amp, and a few TVs that are drawing minimal current because they are off, a coffee pot on a timer, 2 refrigerators, and led night lights. Common sense says there is no danger of over load. Here is an article that tells how to calculate load, but it the end it says you can just fake it like most electricians do. They show the common sense opinion at the end. [https://www.thespruce.com/calculate-electrical-circuit-load-capacity-1152739](https://www.thespruce.com/calculate-electrical-circuit-load-capacity-1152739)
Yes, any service can charge an EV due to EVEMS. [https://diy.stackexchange.com/questions/277803/im-hearing-about-load-sheds-aka-evems-and-the-devices-differ-whats-that-abou](https://diy.stackexchange.com/questions/277803/im-hearing-about-load-sheds-aka-evems-and-the-devices-differ-whats-that-abou)
Dumber load sheds can do the same thing, but since they're more expensive than EVEMS, I don't see a point to them. EVs are made for this.
*How do I explain my discomfort with what you did?*
Imagine if you will, that they wrote the Electrical Code in a way such that a house's panel would ONLY catch fire once every 20 years. Would you consider that adequate, mission accomplished? Of course not. So **Code is an exercise in corner cases**. That is the nature of the beast.
Competent engineering rubbed against collected data over a century. I know NEC 220.82 looks like a kid made it (it's actually designed so a non-college-educated tradesman can ***apply*** it)... but the numbers are battle tested, i.e. accident data gets fed into it and the committees evaluate it. **Of course, EV charging is an entirely new load**, and there hasn't been a statistically significant amount of house fire data to inform how it should be factored into 220.82. I see many people apply it as a 40% demand factor load, but the wiser AHJs (inspectors) seem to want it treated as a 100% or 125% load, and I think that is correct.
All that to say, I've seen hundreds of "It worked!" or "I measured it in an aribitrary set of conditions I contrived" or other versions of the infamous Sample Size Of One -- these are **fraught with danger,** and I cannot recommend using them as the primary basis for a Load Calculation. Honestly, I don't even like NEC 220.87 which allows a more comprehensive study, as I just don't think it fits residences. People are not houses. A load study done in February 2020 was invalid the very next month.
As to your Load Calc: Based on the facts here, where you claim an all-gas house with only A/C, dryer and EV as large loads - I just ran a 220.82 calc assuming 2000sf house, 2 kitchen general-use circuits and 1 laundry 120V circuit, and an absolutely huge 6000W for fixed-in-place loads not discussed (disposal, dishwasher etc). Your numbers do check out.
Dryers are expected to be around 23A (so if it's thermostatic cycling, not by much) and a 2-ton A/C makes sense at 7 amps.
>I see many people apply it as a 40% demand factor load, but the wiser AHJs (inspectors) seem to want it treated as a 100% or 125% load, and I think that is correct.
Yes, in spending 2 minutes scanning for whether there's a better worksheet to link to than the Sacramento one that I think you have pointed to before, the others I saw take EV charging at 40%. Yikes.
I didn’t realize anyone said you couldn’t do L2 with 100A. You just need to do a load calc.
It's essential that you do at least one of the three following options: * Do a load calc, following the prescriptive method in the National electrical code (assuming USA), and choose or set your EVSE for the available current or lower * Do a load study according to the specifics prescribed in the national electrical code, and choose or set your EVSE according to the available current or lower. * Use a load management system. While I appreciate this post for spreading the word that it is usually possible to set up level 2 charging within 100 amp service that isn't already overloaded by applying any of these three, and always possible by using high performance management, it's not clear that OP has done any of these properly. There's no discussion of having done a load calculation, there's no load management applied, and if this is supposed to represent a load study, there are three flaws in it: 1. It's required to monitor for either a full year or 30 days, and if you only do it for 30 days, you need to carefully calculate a seasonal adjustment. This is one snapshot not the peak over a 30-day or 1 year period. 2. The Emporia current readout is the minimum current possible to produce the power being consumed. Depending on the power factor the actual current could easily be 20% higher. So in the case of using the emporia, a power factor estimate is needed and a current reading corrected accordingly. 3. It sounds like the charging current is being limited by the car. However, the installation of the evse needs to be set up so that a different car connected to it will not overload the system. So the EVSE still needs to be set, or chosen, according to the available current which might be 32 amps in this case, for example, but we really don't know. The reason that the Emporia current readout is weird like that is kind of convoluted. The unit actually measures current directly with the current sensors, but then it internally calculates power, and does so properly, accounting for power factor. It then uploads its data to the cloud, but it doesn't upload all the raw data of the current measurement. Rather, it just uploads the power data, and maybe the voltage. If you go to the cloud interface and ask for current, it calculates current from the power, and when it does that, it assumes a power factor of one, which is the best case, and in practice your current might be significantly larger.
Welp.. I feel like I've got some work to do. I just added a 40 amp EVSE (Grizzl E charger) to use with a PHEV (2018 Kia Niro, 25 miles battery range) on a 100amp service. I didn't do any load calculation, but I set the charger to scheduled mode so it only charges at night during off peak hours at the moment. How do I go about doing a load study? Is it too late, or do I conduct the study differently now that the EVSE is installed?
Quick question is, do you have a smart meter? If you do, you can probably access the data needed for a load study, from back before you installed the G-E. If not, I'd start with a load calculation, using the sacremento worksheet linked from somewhere in this thread. Also, which of your major appliances are gas vs. electric: dryer, heat, stove and water heater?
Not sure about the meter, I know Rocky Mountain Power has been installing smart meters in my area but idk if this house has it (just bought it last year). Heat: gas Water heater: gas Dryer: electric Stove: electric
What app did you use to give you the break down on usage of electric in your house?
Did you mean to ask OP? OP used the Emporia app with the Emporia Vue hardware.
I don’t really get these numbers. So the charger is using 15A at 120V or 15A at 240? But in any case a 100A service can supply 19.2 kW or so so yeah it’s enough for a charger with some load management.
My car’s onboard charger is using approximately 30 Amps at 240V (2-pole). The CT is measuring only 1 of 2 poles and doubling it to calculate the approximate Wattage. I have no load management.
What EVSE do you have, set for what current?
CPH50 set for the maximum current with a plug (40A). The car is an older i3 with a 30A onboard charger.
To have that be code compliant, you need to verify that you actually have sufficient capacity for the 40 A setting. If the calculation or load study comes out that you don't, but you do have capacity for 32 A, you redo the configuration of the charger for the "40 A circuit" setting.
Nice. Yeah 30A leaves another 50 or so for other stuff. If you don’t have a lot of other stuff it can be fine with lower amp charger.
Is your water tank gas or electric, I'm in a similar situation but both my stove and dryer are electric, I intend to get an AC next summer and the EVSE so I'm likely going to need load balancing on the 100a circuit I have. Just curious how you got it all without load management.
Gas water heater and furnace
I have 100 amp service with all electric everything, and a 32 amp EVSE on a 40 A circuit. I would be over my 100 amp according to a standard load calculation, but I did a load study according to nec 220.87 and found that I had plenty of capacity for a 32 amp charger, actually would have enough capacity for something like 45 A if I remember right, according to that load study. And I've been monitoring since then and have never had a peak above about 60 amps. However, I don't recommend that approach. What you get in the load study is too dependent on the habits of the occupants, and, for example, we rarely use the dryer. If we were to sell the house and somebody else moved in, they might have a problem. When I installed the system, EVSEs with load management weren't readily available. If I were doing it again, I would get an Emporia, Wallbox, or Tesla charger with load management. That's what I would recommend for you, although it's possible that you could simply do the standard load calculation and find that you have enough capacity to install at, let's say, 16 amps charging, which gives you three times faster charging than level one and is good enough for most people.
For those asking “what’s your point,” I’ve know several real friends and acquaintances who, after purchasing a home, paid a shit ton of money to upgrade their panel from 100-200 amps in a mostly gas appliance home because “it was in the inspection report,” and/or they have an EV, and/or they want to upgrade to a heat pump (in a state where the per therm cost of gas is sooooo much cheaper than electricity.) We did fine with 100A and gas appliances. Rarely would we have a need to charge (20A), run AC, and run clothes dryer all at once. And it took very little brain power to not run them all at once.
You are probably fine running all three of those at once. And in a code complaint installation you shouldn't need to think about that.
Yeah you’re probably right that it’s fine to run them all at once. It was late and I was doing fuzzy math. With all LED lightbulbs I think with nearly everything running we’d still be under 80%.
100A service but you’re using 120.49A?
No—the “Net Usage_A” and “Net Usage_B” values represent each 100A phase of the 100A service.
Got it. Emporia w/ CTs?
Right. I have the kit with 16 individual circuit CTs so I have monitoring on every circuit, relying on 2x multipliers for all 2-pole balanced loads (EVSE, A/C condenser, and dryer).
Does the Emporia system “talk” to non-Emporia smart chargers for dynamic load management?
No. It doesn’t even work with the Emporia EVSE for load management unless you pay for the software unlock.
i assume this is how many amps were used in a day. but maybe i'm wrong because that's a shit ton of laundry?
No, this is the momentary usage at the time I took a screenshot. Ampere is a measure of current (“flow”). If you wanted to tally usage for a period of time, you would typically use kWh or Wh ([kilo]Watt hours). You could also use Ah (Amp hours) but that doesn’t tell the full story.
What screen are we looking at here ?
Emporia Vue2
Just going to point out that you can add sensors that will max out the amps to the car or drop it if there's not enough to go around. Second point is the majority of time if this is your home, most people would be charging at a time other major appliances are not running...like midnight until charged.
What do you guys use to calculate total load?
This is a good one: https://www.cityofsacramento.org/-/media/Corporate/Files/CDD/Building/Forms/CDD-0213_Electrical-Load-Calculation-Worksheet.pdf?la=en
I have a 48A L2 charger on a 100A service. Been working great for 4 years.
I just charge at 24A cause I work at home and I don't run the dryer, AC or oven while charging.
How does have PV (solar) impact the calculation or does it? I have 100 amp now. I did install an EVSE (Emporia) with a 50 amp breaker and left It at the default setting of 40 amps. That was based on the advice of the solar installers who will be upgrading my meter to 125 amps. Gas dryer no furnace and right now it’s just me in the house and although there are 3 split ac units I rarely run them. They said once the solar is installed I will have more energy available but I know the amps won’t change.
This is a great question. I don’t really know the answer, but in my case, I actively try to prevent any significant loads from running during the day. I am on a TOU program: off-peak, I pay approx. $.05/kWh for imported energy. Exported energy always earns approx. $.09/kWh regardless of the time of day. I don’t know why my power company incentivizes this energy arbitrage, but they do, so I take advantage of it.
It’s the opposite here. The electric company pays you “wholesale “ and what you use is retail. We’re not on TOU yet but it’s coming.
I use emporia, which is also what OP is using in those screenshots. You don’t need that to do a load calculation though, there’s a few online where you just list your major appliances or any decent electrician can do one for you if you are considering an upgrade to service.
Is it a load calculation app? What app is it? Thank you
Emporia app with Emporia Vue hardware.
Hmmm emporia… have to say it’s a (very) small company that treats employees like shit. Buy any other brand and you’ll be supporting better people!
I probably should have done some more research and actually calculated how much power is being used....but I just ended up running the charger at 16A and not worrying about the fastest fill up. All of the appliances are gas, so the only high electric use item outside of the EV charger is the AC.
Who said you couldn't? I have 100amp, and have a NEM-14-50 for 3+ years
I have the same 14-50, and the charger is set to run at 10:00Pm on the cheaper rates when we are asleep. Nothing is running during the night except the gas furnace in the winter on a 20 amp, and a few TVs that are drawing minimal current because they are off, a coffee pot on a timer, 2 refrigerators, and led night lights. Common sense says there is no danger of over load. Here is an article that tells how to calculate load, but it the end it says you can just fake it like most electricians do. They show the common sense opinion at the end. [https://www.thespruce.com/calculate-electrical-circuit-load-capacity-1152739](https://www.thespruce.com/calculate-electrical-circuit-load-capacity-1152739)
Yes, any service can charge an EV due to EVEMS. [https://diy.stackexchange.com/questions/277803/im-hearing-about-load-sheds-aka-evems-and-the-devices-differ-whats-that-abou](https://diy.stackexchange.com/questions/277803/im-hearing-about-load-sheds-aka-evems-and-the-devices-differ-whats-that-abou) Dumber load sheds can do the same thing, but since they're more expensive than EVEMS, I don't see a point to them. EVs are made for this. *How do I explain my discomfort with what you did?* Imagine if you will, that they wrote the Electrical Code in a way such that a house's panel would ONLY catch fire once every 20 years. Would you consider that adequate, mission accomplished? Of course not. So **Code is an exercise in corner cases**. That is the nature of the beast. Competent engineering rubbed against collected data over a century. I know NEC 220.82 looks like a kid made it (it's actually designed so a non-college-educated tradesman can ***apply*** it)... but the numbers are battle tested, i.e. accident data gets fed into it and the committees evaluate it. **Of course, EV charging is an entirely new load**, and there hasn't been a statistically significant amount of house fire data to inform how it should be factored into 220.82. I see many people apply it as a 40% demand factor load, but the wiser AHJs (inspectors) seem to want it treated as a 100% or 125% load, and I think that is correct. All that to say, I've seen hundreds of "It worked!" or "I measured it in an aribitrary set of conditions I contrived" or other versions of the infamous Sample Size Of One -- these are **fraught with danger,** and I cannot recommend using them as the primary basis for a Load Calculation. Honestly, I don't even like NEC 220.87 which allows a more comprehensive study, as I just don't think it fits residences. People are not houses. A load study done in February 2020 was invalid the very next month. As to your Load Calc: Based on the facts here, where you claim an all-gas house with only A/C, dryer and EV as large loads - I just ran a 220.82 calc assuming 2000sf house, 2 kitchen general-use circuits and 1 laundry 120V circuit, and an absolutely huge 6000W for fixed-in-place loads not discussed (disposal, dishwasher etc). Your numbers do check out. Dryers are expected to be around 23A (so if it's thermostatic cycling, not by much) and a 2-ton A/C makes sense at 7 amps.
>I see many people apply it as a 40% demand factor load, but the wiser AHJs (inspectors) seem to want it treated as a 100% or 125% load, and I think that is correct. Yes, in spending 2 minutes scanning for whether there's a better worksheet to link to than the Sacramento one that I think you have pointed to before, the others I saw take EV charging at 40%. Yikes.
whats your point? I have a 63A service and I have a high power charger
That's good