[jrref]

When installing an EV charger in your home for an all electric vehical, has anyone had an electrician do a load calculation to make sure the added power needed for the charger doesn't exceed the capacity of all the loads connected to the main electrical panel? In a home with gas appliances this may be less of a concern but with an all electic home, even with a 200 amp panel, depending if you have pool equipment and or a hot tub, adding a 48 amp EV charger might be a problem.

I'm sure some install the charger themselves and hope for the best because they are convinced they never draw anywhere near 80% of the panels main breaker.

Some have electricians who just install the charger without any load calculation.

Some have electricians who do the load calculation and in some cases the homeowner may need an expensive electricial panel upgrade.

Tesla has a new power management device that's relatively cheap to monitor the current at the panel and if it reaches a preset limit, the charger will back-off and reduce the current it needs until the total current draw at the panel decreases. This enables you to install an EV Charger that can draw 48 amps in a home with smaller electrical service. You can either hardwire the power manager to the charger or it has a wifi interface. They came up with this because in older homes you might have 100 or 150 amp service and getting an electric vehical with a 48 amp charger will require a costly electrical service upgrade.

[CarlR33]

I am looking to do the same thing soon. You’re way overthinking this without even consulting an electrician for your current home needs. I will hire a licensed electrician that will walk me through this. Duke Energy currently has a program to reimburse you for adding a charger and you have to use their electricians for the install to qualify. I follow the Tesla online forums and have never heard of anyone needing to add a panel. The added electric is similar to an oven outlet. BTW, the Tesla charger specs have the required amperage up to 60 amps (attached photo). You can install with less amps but will get a slower charge. You can also purchase the regular 110 amp charger that plugs into a regular outlet if you do not want the wall charger or find out something about the wall charger will not work (doubtful).

[jrref]

Actually, I'm an electrical engineer and intially thought as you, no issue adding a device like this. But when I did speak to my electrician who I know well, what he was saying made sense.

In my home for example these are the following that potentially could be ON at the same time:

1) Heat strips from HVAC equipment in the winter when the unit is in defrost mode and the home calls for heat - 40Amps for my 4 ton unit. My new heatpump will work efficiently down to 0 degrees so I would never expect the heat strips to ever come on during normal heating here in the Villages.

2) Clothes Dryer - 24 Amps

3) Induction Cook Top - 30 Amps ( would need most or all the burners ON high to reach this draw which we never do )

4) Water Heater - 24 Amps

5) Hot Tub if the heater goes ON - 40 Amps This can happen if in the winter the hot tub senses the temperature of the water going below the 50 degrees which is very rare Or in the summer when we are using the Tub but at that time of year the heat strips on the HVAC unit would never come ON.

This totals 158 Amps. If you add the 48 Volt EV Charger then that's 206 Amps which is way over the capacity of the panel. (80% of 200 Amps = 160Amps) Please note, this is not a load calculation but a common sense view at a high level of what the peak load could be since many of these appliances are resistive loads. There are load calculators available to find the true power consumption of your home. Of course the possibility of all these appliances being on at the same time is very remote.

So, I found this from AI:
How to Calculate Peak DemandThe Math: kWh in 15 minutes × 4 = average kW demand for that specific window.

Finding the Peak: Scan your historical interval data (ideally covering a full 12-month cycle) and find the single 15-minute block with the highest calculated kW value.

Code Approval: Under specific electrical codes like the National Electrical Code (NEC 220.87), using actual maximum demand data from a 15-minute interval over a 12-month period is an approved method to calculate existing load before adding heavy loads like EV chargers.

So, I went on the Seco web site and pulled up my electrical usage. If you go to the Explore tab you can see and find the max Kwh your home uses on a monthly, daily or interval basis. I found that in my home the highest Kwh usage was in Febuary of 2026. You can then double click on that peak and get the Kwh usage at 15 minute intervals for that day. Doing some calculations to convert Kwh to Amps, in my case the highest current my home ever used was 48 Amps in a years time. Adding the 48 Amp charger would bring me to 96 Amps. Well under the capacity of my 200 Amp panel.

Update: When looking at daily intervals on the electric meter I realized it is possible for a peak demand to happen even on a lower Kwh day for a short period of time. So, I then looked at 15 minute intervals each month for a year and still my home never drew over 62 Amps at any time during the year.

Then I was thinking about my neighbors who have EV chargers and have a Pool that has it's own heatpump to heat it, Spa, mini-split in the garage and all have the same electric appliances as I do. They didn't upgrade their electrical service and are not having problems. I will bet if I did a real load calculation on their home they would be way over.

Then I see other neighbors installing the EV charger themselves or using a handyman, again no issues.

All this said, what would happen if you overload the panel? You would trip the main breaker. So, as long as the charger is installed as per the electrical code, if this every happened you could install the Tesla energy monitor to reduce the charger's current when the home ever draws near the 80% limit of the panel.

[CarlR33]

LOL, you can schedule the car to charge late night like 12-6 am so I doubt you will be operating your other appliance during this time. The electrician I spoke to had been installing these and I doubt he would risk his license on setting my house on fire. If others have installed as DIY then that is their own risk and possibly risking their home insurance should something occur as a result of the DIY.

[SoxOfRed]

Originally Posted by jrref

When installing an EV charger in your home for an all electric vehical, has anyone had an electrician do a load calculation to make sure the added power needed for the charger doesn't exceed the capacity of all the loads connected to the main electrical panel? In a home with gas appliances this may be less of a concern but with an all electic home, even with a 200 amp panel, depending if you have pool equipment and or a hot tub, adding a 48 amp EV charger might be a problem.

These are great questions and (I think) important. I'm not an electrician but am curious how things work so I love these discussions.
When EVs are new to you you have all of these (legitimate) concerns. Once everything is in place, no longer a thing.

The practical side of this would be if you have less than a 200 amp panel you do have to worry, although having enough physical breaker space might be an issue before you ever run into a problem with the house drawing too much power.

If you already have a pool and a hot tub and other things you (or an electrician) probably have addressed this before putting those in.

Don't know how much you drive but you probably won't spend a whole lot of time charging, however, if you're concerned about power use, charge at night (after midnight to make the power company happy). Likely you won't be going from a low battery to a full charge so, at most, maybe a couple hours if charging at full 48amps.

I drive about 12K miles a year (so much for leisurely retirement!) and rarely charge more than few hours every three days or so. Car stops charging at 80% and don't plug it in unless below 60%.

[jrref]

Originally Posted by CarlR33

LOL, you can schedule the car to charge late night like 12-6 am so I doubt you will be operating your other appliance during this time. The electrician I spoke to had been installing these and I doubt he would risk his license on setting my house on fire. If others have installed as DIY then that is their own risk and possibly risking their home insurance should something occur as a result of the DIY.

Agreed, you can schedule the car to charge late at night. You wouldn't start a fire, you would just trip the main breaker.

What did the electrician you spoke to say about electrical capacity?

[CarlR33]

[QUOTE=jrref;2525908

What did the electrician you spoke to say about electrical capacity?[/QUOTE]

I did not ask and would assume if an issue they would have said something. Btw, the electrician was onsite and when any electricians have run extra breakers for my patio screens and such they always look at the main box first. Im getting a pool soon and the estimator looked at the panel first. Pool is permitted so I doubt they will short cut anything (T&D).

[Pugchief]

Originally Posted by jrref

Agreed, you can schedule the car to charge late at night. You wouldn't start a fire, you would just trip the main breaker.

Why would it trip the breaker? If you set to charge while you sleep, you can add 300+ miles of range at 240v in 6 hours. Other than the AC and fridge, you won't be using any other electricity besides minor power draw. This is ZERO concern. I've been doing it for years and have NEVER had a breaker trip. Even on rare occasions I have to add range during the day, I am still able to use whatever appliances I want without issue.

This is a solution looking for a problem.

[biker1]

Agreed. I have never had a problem with my Tesla and and a Tesla Wall Connector. I have 200 amp service. If you have a smaller panel, say 100 amp service, you can dial down the amperage when you configure the Wall Connector or via the app or with the car's user interface. I charge at night but it doesn't really matter. I added up the maximum potential simultaneous power draw and it isn't close. This is a non-issue for the vast majority of people. I suspect the OP doesn't have an EV so he doesn't really understand.

Originally Posted by Pugchief

Why would it trip the breaker? If you set to charge while you sleep, you can add 300+ miles of range at 240v in 6 hours. Other than the AC and fridge, you won't be using any other electricity besides minor power draw. This is ZERO concern. I've been doing it for years and have NEVER had a breaker trip. Even on rare occasions I have to add range during the day, I am still able to use whatever appliances I want without issue.

This is a solution looking for a problem.

[jrref]

Originally Posted by biker1

Agreed. I have never had a problem with my Tesla and and a Tesla Wall Connector. I have 200 amp service. If you have a smaller panel, say 100 amp service, you can dial down the amperage when you configure the Wall Connector or via the app or with the car's user interface. I charge at night but it doesn't really matter. I added up the maximum potential simultaneous power draw and it isn't close. This is a non-issue for the vast majority of people. I suspect the OP doesn't have an EV so he doesn't really understand.

No I do understand, just curious what others were doing when adding EV chargers, pools, spas, etc. in a house that is all electric. In a house that has gas, there is significantly less electrical load so you have a lot more capacity to add to your home.

But what I’m gathering is most charge at night so even in an all electric home you would never run into an issue.

Just fyi, If you go into a large Premier all electric home with a pool, etc, many are built with two electrical panels.

Anyway thanks for all the feedback.

[Topspinmo]

If you are at or close to maximum 200 amp service in all electric house with pool, electric dryer, A/C/electric heat, electric stove ext… IMO you have two options ? Manage using of high amps current drawing circuits or upgrade to 400amp service which usually require bigger gage wires ran to house or separate wires to added to another main breaker? Either way with underground buried wires probably very expensive? IMO management probably best case scenario? If you have all the high amp drawing stuff. Which probably need electrician or do math yourself see it you may have over load problems? See if safely to add another high draw circuit?

When I added my shop in all electric 2500 sq ft home I had to have separate service line and meter ran due to length to shop and my 200 amp panel was 75% its capacity.

Yelp, I got two I got two monthly bills with two meters.

[jrref]

Originally Posted by Topspinmo

If you are at or close to maximum 200 amp service in all electric house with pool, electric dryer, A/C/electric heat, electric stove ext… IMO you have two options ? Manage using of high amps current drawing circuits or upgrade to 400amp service which usually require bigger gage wires ran to house or separate wires to added to another main breaker? Either way with underground buried wires probably very expensive? IMO management probably best case scenario? If you have all the high amp drawing stuff. Which probably need electrician or do math yourself see it you may have over load problems? See if safely to add another high draw circuit?

When I added my shop in all electric 2500 sq ft home I had to have separate service line and meter ran due to length to shop and my 200 amp panel was 75% its capacity.

Yelp, I got two I got two monthly bills with two meters.

I'm just curious. What kind of shop did you have to need a separate service line? Was it here in the Villages?

[Topspinmo]

Originally Posted by jrref

I'm just curious. What kind of shop did you have to need a separate service line? Was it here in the Villages?

No, in Oklahoma. On around two acres. Shop (actually pole barn) with electric Rollup doors, electric heaters, 220V access for welders, truck lifts, air compressor. Code required separate electrical supply due to length cable from under ground power supply which came from different line being it was at back property.

[jrref]

I'm not surprised but talking to more of my neighbors, some had their EV chargers installed correctly and some not. The ones who had it installed by a licensed electrician or DIY who knew what they were doing had the charges installed correctly. But, I did find a couple who had a handyman install theirs possibly incorrectly. One used a 50 amp breaker and told the customer to set the Tesla charger to a lower charge rate. Not sure what guage wire they ran. Another, ran the wrong type of wiring with a 60 amp breaker. So far the EV chargers are working but some of the work I saw was pretty scary. Also, the work done by a Handyman was significantly cheaper than done by an electrician which may be the reason some are using them. There were a couple of Handyman installs that I saw which were fine and done correctly.

I think most of the errors are because some don't realize If you use 6-gauge Romex (NM-B) purchased at one of the big box stores, you can only use a 50-amp breaker for a maximum continuous charging output of 40 amps. You cannot use it for a full 60-amp breaker (48-amp charging) because 6-gauge Romex is limited to the 60°C ampacity rating of 55 amps under the National Electrical Code, and continuous EV loads require sizing down.

The correct type of wire for a 60-Amp Circuit (48A output) for a Tesla EV charger for example, is minimum 6 AWG copper wire rated at 90°C (such as THHN in conduit) paired with a 60-amp double-pole breaker. Note that standard 6-gauge Romex (NM-B) is only rated for 55 amps, so it cannot safely max out a 60-amp breaker.

I think another issue is some homeowners don't take electrical wiring seriously enough thinking as long as it works, it should be fine but if fires or any other problems caused by code violations occur it can void you home insurance policy.

[biker1]

I believe this is well known in the Tesla community and is documented in the Wall Connector instructions. Your choices essentially come down to 6 gauge THHN in a conduit, 4 gauge NM-B, and 6 gauge NM-B. The vast majority of people will use 6 gauge NM-B so they don't have to bother with a conduit with THHN and 4 gauge NM-B is difficult to pull. The decrease in max charging rate with 6 gauge NM-B is minimal; 40 amps vs 48 amps. When you configure the Tesla Wall Connector, you simply tell it that it is connected to a 50 amp breaker and the maximum, selectable charging rate is 40 amps. I suspect many people don't use the highest charging rate anyway. For example, I charge at 24 amps. I actually used 6/3 NM-B (the Tesla Wall Connector only needs 6/2 but if I wanted to swap to something else that needed 6/3 I wouldn't need to pull another cable, which was a bit of a pain). BTW, the term "charger" is a bit of a misnomer. The charger is actually in the car. Tesla calls it a "Wall Connector" and others call it an EVSE.

Regarding your comment about using a 50 amp breaker and telling the customer to set the Tesla Wall Connector to a lower charging rate, that was probably correct. He probably used 6/2 NM-B and when the Tesla Wall Connector is configured, presumably by the customer and not the electrician, it will ask for the rating of the breaker and then provide 80% of that figure as the maximum, selectable charging rate in the Tesla app or the car's user interface.

Originally Posted by jrref

I'm not surprised but talking to more of my neighbors, some had their EV chargers installed correctly and some not. The ones who had it installed by a licensed electrician or DIY who knew what they were doing had the charges installed correctly. But, I did find a couple who had a handyman install theirs possibly incorrectly. One used a 50 amp breaker and told the customer to set the Tesla charger to a lower charge rate. Not sure what guage wire they ran. Another, ran the wrong type of wiring with a 60 amp breaker. So far the EV chargers are working but some of the work I saw was pretty scary. Also, the work done by a Handyman was significantly cheaper than done by an electrician which may be the reason some are using them. There were a couple of Handyman installs that I saw which were fine and done correctly.

I think most of the errors are because some don't realize If you use 6-gauge Romex (NM-B) purchased at one of the big box stores, you can only use a 50-amp breaker for a maximum continuous charging output of 40 amps. You cannot use it for a full 60-amp breaker (48-amp charging) because 6-gauge Romex is limited to the 60°C ampacity rating of 55 amps under the National Electrical Code, and continuous EV loads require sizing down.

The correct type of wire for a 60-Amp Circuit (48A output) for a Tesla EV charger for example, is minimum 6 AWG copper wire rated at 90°C (such as THHN in conduit) paired with a 60-amp double-pole breaker. Note that standard 6-gauge Romex (NM-B) is only rated for 55 amps, so it cannot safely max out a 60-amp breaker.

I think another issue is some homeowners don't take electrical wiring seriously enough thinking as long as it works, it should be fine but if fires or any other problems caused by code violations occur it can void you home insurance policy.