Will my electrical panel support my EV charger?

Jesse Kuhlman News

Is Your Electrical Service Too Small For an EV Charger?

You ordered your new fully electric car, and you are excited! Now you are wondering if your homes electrical service can charge the car.  It is a great question that every new EV owner is asking themselves. Let’s take a look at some of basics first, and I’ll try my best to help you determine if your existing electrical service will support it!

Faster Charging Speed = More Power Needed

Probably obvious, but the faster your charge rate the more power it takes. Let’s take a look at a Tesla charge rate and amperage chart using a tesla wall connector for reference. 

As you can see in the chart above, the fastest charge rate for a model 3 is 44 miles an hour. To get this charge rate you will have a current draw of 48amps.  Yeah, 48amps is A LOT!!  If you are willing to live with a slower charge rate, you can get as low as 12amps. The good news is that Tesla’s, like all other electric vehicles have charge options that will work for almost anyone.

I Want my Car to Charge as Fast as Possible!

Most people don’t really need a maximum charge rate. Using the Tesla Model 3 as an example, at its maximum charge rate it will charge the car 44 miles an hour.  If the car has a 300 mile range, this means it will charge from near depleted to full in under 7 hours.

Two things to consider. First, when will you charge your car and what kind of charge window do you have?  Second, are you going to drive nearly 300 miles a day and completely drain the battery?

Let us look at the first – When will you charge your car? Overnight like 98% of people?  How long is overnight to you? For many people they may get home from work by 5 or 6pm and may not leave the house until the next morning. This could give you a 12-hour charge window. 

How many miles do you drive? The average person drives roughly 37 miles a day.  If you are driving anywhere near the average, you do not need a maximum charge rate.  Let’s say you drive 100 miles a day for example, far exceeding the national average. A charger set at even the 30amp setting will charge your car in 4.5 hours (Model 3 example).

If it turns out your electrical service is a little undersized, really think about how much you drive before you commit to a service upgrade. You might be fine with the slower charge rate!

Determining if my Electrical Service will Support an EV Charger

There are a number of factors that go into this including:

  • Existing service size – 100amp, 200amp, bigger?
  • What charge rate do I need?
  • Other electrical loads in the home. Do I have central air condition, electric range, electric dryer etc?

Let’s start with the existing service.  If you are unlucky enough to have an old 60amp electrical service to your house or condo, there is pretty much a zero chance of any kind of EV charger being installed.  You will have to explore a service / electrical panel upgrade.

If you have a 100amp electrical service and ALL electrical appliances including a central air conditioning. It’s unlikely you will be able to install an EV charger.

If you have a 100amp electrical service and limited electrical appliances (Gas cooking, gas water heater, no central air conditioning, etc) you will be able to have an EV charger installed.  It might not be at the maximum charge rate, but it should still be possible at a lower speed / amperage.

If you are lucky enough to have a 200amp electrical service, you should be good to go.  However, if your house is huge with all electrical appliances and multiple central air conditioners it might be close!

Electricians perform what is called an electrical load calculation to determine the current homes electrical load.  Once that it determined the maximum EV charger amperage can be figured out. These load calculations take into account the square footage of the home and electric appliances. A calculation is performed using some demand factors, meaning our code assumes you will never use ALL your electric appliances at the same time and allows some reductions.

The electrical load will vary from home to home.  If you are unsure about your own electrical load, and whether an EV charger is possible, email us! We would be happy to provide an electrical load calculation for you. To do this, we need the following:

  • Square feet of home
  • List of electric appliances (Dishwasher, disposal, water heater, dryer, fridges, microwave, trash compactor, garage door openers, etc)
  • Name plate rating of your central air condenser (you can take a picture of the label on the unit outside)
  • If you have any electric heat, what is it? Amperage rating?
  • What is your existing service size? (Usually 100amp or 200amp for single family homes)

With the above information we can do a quick load calculation and start the estimate process.

OK, My Electrical Service Will Not Support The EV Charger, What Should I do?

You have two options:

  • Upgrade your electrical service
  • Install an energy management system

If you have a 60amp or 100amp electrical service and you live in a single family home, I’m a fan of upgrading to 200amps.  This will give you a larger panel and lots of capacity for future electrical projects.  And if you ever sell the home, buyers and home inspectors LOVE to see a house has a 200amp service.

If you already have a 200amp service and live in a single family house, or have a 100amp and live in a condo, the energy management system is the way to go.  These units work by measuring the total load being drawn by the electrical panel and will shut OFF the power to the EV charger if the load exceeds 70%.  When the load falls, it will restore power to the charger.  This all happens automatically. These units circumvent the need for a load calculation. It is an excellent product.

I like the energy management systems in these cases as it will be FAR cheaper than the alternative. Upgrading a single family home from 200amp to 400amp is very expensive. In the condo example, it might be impossible to upgrade your unit from its current 100amps.  If it is possible, this may mean upgrading the entire building service which believe me, no one else will want to help pay for! 

Need Help Figuring It Out?

We are both Tesla and Qmerit certified installers.  We have been specializing in EV charging solutions for residential customers for years! All brands of cars.

Feel free to contact us for assistance. We would be happy to take a look at your individual situation and offer some recommendations! https://www.kuhlmanelectricalservices.com/contact/