Electric vehicle charging safety has thus far been an underserved topic. Even when it's done correctly, there's the possibility of an equipment failure, which shouldn't necessarily result in a critical problem as long as the installation was done correctly.
However, when corners are cut, when inferior equipment is used, and when the installation is done by someone unaware of the unique challenges that EV charging presents, you can end up with a disastrous result.
In this article, we will explore why EV charging equipment requires special attention, and offer our best practices to ensure you don't have a problem with your home charging equipment.
A collection of EV charging equipment failures we've seen on various forums and online EV groups
Types of EV Charging
In North America, there are three basic types of electric vehicle charging:
- Level 1: 120-volt, simple household outlet
- Level 2: 240-volt, hardwired or 240-volt outlet
- DC Fast: 400-volt to 1,000-volt public stations (sometimes called Level 3)
We're going to be focusing on level 1 and level 2 charging here because that's the type of electric vehicle charging equipment that's installed in private homes and workplaces. DC fast charging equipment requires very high power delivery which most residential buildings don't have access to. Also, the cost (in the many tens of thousands of dollars) is prohibitive for home installation even if the power were available.
EV Charging Is Unique
Electric vehicle charging is different than other electrical devices in the home. That's because of the high amount of current that EV charging demands and the fact that it's being delivered to the vehicle for many continuous hours and often every day of the week.
While you're charging your EV, chances are the charging equipment is delivering more current to the vehicle than the rest of your house is using, and it's all passing through the wiring and connections on the charging equipment circuit. To make matters worse, this high-power draw is being done for many continuous hours, which qualifies the circuit as a "continuous load". The NEC definition of a continuous load is a load where the maximum current is expected to continue for 3 hours or more.
The longer a circuit is energized, the more it heats up and the connections can become stressed. Heat causes expansion, then the wiring cools off and contracts after charging is complete and over time the expansion and contraction can loosen the connections.
It's made worse by the fact that EV charging equipment is usually installed in unheated garages and often outside, and in cold weather areas, the wiring can be exposed to 50°F to 80°F temperature swings on a daily basis. That's enough to back screws out of their connections if they aren't properly torqued to the manufacturer's specifications.
EV Charging Installation Best Practices
Inferior Equipment Can Lead To Problems
There are a lot of choices when purchasing electric vehicle home charging equipment, and choosing the right unit for your needs will depend on the power your EV can accept, the features you'd like to have and the budget you have to spend. However, the one overriding feature you should not overlook is making sure the device is safety certified.
Safety certification from an established testing and certification lab is critical so you know the device is safe to use. We recommend only buying EV charging equipment that has been approved by either UL, ETL, TÜV, or CSA, and the body of the unit has the certification label printed on it.- don't trust the description on the Amazon page because they often lie and say it's safety certified when it isn't.
Once you've selected the charging equipment you need to have it installed. Level 2, 240-volt Charging equipment can be permanently mounted and hardwired, or it can be a plug-in unit, which can be unplugged and easily removed from the wall. Level 1 charging equipment simply plugs into a regular household outlet.
Level 1 charging is very slow charging, and only adds about 2 to 4 miles of range per hour. For that reason, most EV owners will choose to charge from a level 2 charging source for home charging. Level 2 charging can deliver between 15 and 50 miles of range per hour, depending on the power delivery and the driving efficiency of the EV.
Use the right type and gauge of wire, and always use copper wire, as aluminum wire is softer, weaker, and more prone to expansion and contraction.
Hardwired vs Plug In
Hardwiring your level 2 EV charging equipment is the best policy because it reduces the number of potential failure points. If you really want a plug-in unit, make sure you install a high-quality 240-volt outlet, which is typically either a NEMA 14-50 or a NEMA 6-50. There are a few different companies that manufacture these outlets and they are not all created equal.
Leviton, for instance, makes a low-cost option that is widely available at local hardware stores and can cost as little as $20.00. However, we've seen many of these budget outlets fail under the strenuous duty cycle that EV charging places on the outlet. The inexpensive outlets may be fine to be used as a clothes dryer plug, but when you run 40-amps through them for 6 hours a day, 7 days a week, they may not stand up to that kind of use and bad things happen. Therefore, make sure you get a high-quality outlet, one that's available from an electrical supply house, not the $20 Home Depot special.
Hire An EV-Charging Equipment Professional
Finally, and perhaps the most important piece of the EV charging equipment installation puzzle is to hire a licensed electrician, preferably one that specializes in EV charging installations. Yes, any electrician can pull a permit and install home charging equipment, and most of the time, everything will be done properly.
However, there are licensed electricians out there that don't always know the latest code, who don't perform the necessary load calculations before installing EV charging equipment, and who cut corners to save time and money.
Your EV is pulling a lot of power, for many continuous hours, sometimes every day and often when you and your family are sleeping, which is just about the worst time to have a problem. EV charging equipment installation isn't a hobby or a task for the weekend do-it-yourselfer. Hire a licensed EV charging equipment professional, pay a little more for high-quality materials, pull a permit so it gets inspected and you'll sleep a lot better at night, knowing you've done everything you can to ensure the job was done right.
So check out the video for a more in-depth discussion on EV charging safety, including a conversation with Qmerit EV charging equipment installer, Matt Trout.