I have a confession to make. For 4 years I charged my electric car using a 50-foot long, yellow extension cord. I would plug the cord into an 120V outlet on the side of my house and run it over my retaining wall, across the sidewalk (covered with a cord protector for safety), and attach it to my car charging cord, which I placed under a large plastic box to protect it from the rain.
Across my neighborhood and city I’ve noticed increasing numbers of people doing something similar. Many of us park on the street because we don’t have a garage or driveway, yet still want to take part in clean, cheap, electric mobility and the convenience of charging from home. 75% of EV owners in Britain admit to using an extension cord to charge their cars, and an informal poll by Green Car Reports showed that 61% of American EV owners had used one to charge at least once or twice.
Is a cross-sidewalk extension cord a legitimate way for EV owners to reach a steady supply of sweet electrons?
The answer is, probably not, at least not on a regular basis. While researching this article, and talking with charging professionals, I became convinced that there are pretty good reasons why automakers recommend against using extension cords (which I’ll talk about below). And this research pushed me to find a better solution for my own charging challenges — a 240V outlet installed at the edge of my property, which has changed my life for the better.
Why People Use Extension Cords To Charge
63% of all homes in the US have a garage (or carport). But as we quickly electrify transportation, the 37% of Americans who don’t (many of whom include renters) are going to need charging options close to home. EV owners without driveways could, in theory, just charge at Level 3 fast charging stations every once in a while or at supermarkets with Level 2 charging amenities. But as my photographic evidence seems to prove, either because charging infrastructure is not yet widespread enough, or because the ubiquitous outdoor outlets and the convenience of home charging is too powerful, many EV owners reach for an extension cord when their charging cable doesn’t reach an outlet.
Bureaucracies Move Slowly
Many EV owners will continue to improvise with extension cords until local governments decide to build on-street charging infrastructure accessible for every apartment and home. As far as I can tell, planning departments are hardly moving to address the challenge (a good paper is here on some of the early leaders).
When my family upgraded from an 85-mile range 2013 Nissan Leaf to a 320-mile range Tesla Model 3 in 2019, I called the planning department of the city where I live (Portland, Oregon) to ask if they were close to coming up with rules for homeowners to put electricity in the public “right of way” (city-owned strip of land between private property and the street). We were ready to pay the cost of running electricity from our house to the street and to pay for the charging station, which we would use regularly and happily make available to others as well. Alas, even in a progressive city, in a state with the third highest per capita rate of EV ownership in the nation, there is still no legal way to do so. I was told, “We’re working on it,” by the planning department. I did a quick search, and it looks like the city has been working on this task since 2010, so I’m not holding my breath. “Until we come up with a solution you could always use an extension cord,” I was told, “though we can’t officially recommend that.” Figuring out how to legally permit on-street charging is not something we have the luxury of waiting decades for cities to figure out. As with everything, climate change is demanding we move much more quickly than we’re accustomed to.
Some cities are further along than Portland and leading the way towards street charging. Amsterdam has installed hundreds of on-street charging stations, with thousands more planned. Los Angeles has installed over 400 Level 2 charging stations on street lights, and London is following suit. But these cities seem to currently be the exceptions, not the rule, and in many places it’s impossible to charge your car on the street even if you’d pay to run electricity there yourself.
Why Extension Cords Are Risky
Those of us using extension cords, as a work-around to cities-moving-like-molasses, aren’t doing the best thing either. In researching this article, and trying to figure out my own on-street charging setup, I talked to local charging guru Rick Durst, who installs charging stations across my state of Oregon.
The first thing that Rick told me was that using an extension cord was unsafe, plain and simple. There is a reason that the charging cords that come with your car are under 25 feet long, as there are lots of ways using an extension cord can go wrong.
Wrong gauge extension cord: Many people (myself included) in need of a couple (or 50) extra feet to reach an outlet grab the standard extension cords laying around the house, which are typically 14 gauge. Not good! When you’re charging over long distances, for long periods of time, you need heavier gauge (thicker) wire. The worrisome trend observed in almost all the cars I’ve photographed is that they are using standard, thin wire, 14- or 16-gauge extension cords to charge their cars. My neighbors’ 14-gauge extension cord melted and fused with their car charger, and mine overheated a couple times too. A heavy duty 10-gauge extension cord is much better than the standard ones people have laying around.
Continuous use: When I trickle-charged (power from standard outlet) my car, it took upwards of 60 hours to go from nearly empty to full. Rick told me that cords rated for continuous use have more requirements than cords that aren’t, which makes sense. Again, the typical extension cord in your utility room probably won’t do the trick.
Voltage drop: The longer the cord, the more electricity voltage can drop. When the voltage drops, more electricity flows through the wires to make up the difference. This “causes wires to heat up and appliances to run hotter.” Not a good thing (read more here on why).
Coiling up on itself: When the extra lengths of a long cord are coiled up, they can create an inductor which can get really hot, melt the outer insulation and cause fires.
Weather resistant: Those of us who use any old extension cord for long periods outside may not be using outdoor rated, weather resistant ones which means the cords could break down more easily.
Bad setups: Any outdoor charging should be in a weather-protected “in-use” outlet on a dedicated circuit. A person should also have a cover over the connection between the extension cord and the car charging cable.
If you read between the lines, someone determined to use an extension cord could use the above “no-nos” to do it more safely. Use a 10-gauge cord that is outdoor and continuous use rated. Don’t coil the cord up on itself. Don’t use too long a cord or the voltage will drop. Have a dedicated 20-amp circuit that feeds the outlet you charge from with a weather protected bubble cover. Cover the point where an extension cord and a car charger connect. But after four years of charging with an extension cord and a couple close calls, I agree with Rick that it’s “It’s unsafe to do even if you can make it safer,” and so I came up with another setup to charge my car at home.
Running An Outlet To The Edge Of My Property
If a person doesn’t have a garage or driveway and shouldn’t use an extension cord, is charging from home impossible? Rick Durst gave me another option. He suggested that I have an electrician run a wire properly to the edge of my property and have an outlet and box mounted there.
So that’s what we did. I dug a trench and had an electrician make room in our circuit breaker and run 240-volt wire through outdoor-rated conduit and attach it to our retaining wall.
And voila! With Rick Durst’s inspiration we suddenly have access to a 240-volt outdoor-rated outlet that my 20-foot car charging cable will reach. No more extension cord overheating risk or waiting on the city bureaucracy to allow us to run power to the right of way. I still have to run the floor cord protector over the sidewalk, but my charging times have gone from 50 hours to 5 and so I use one much less.
The project for labor and parts came in around $500. Now we have a 240-volt outdoor-rated outlet that charges safely and like a dream.
Our new charging setup is a safe workaround for slow-moving bureaucracies that don’t yet let homeowners put electricity next to the street. And best of all, we no longer rely on risky, problematic extension cords but still enjoy the convenience and cost savings of charging from home. What’s your on-street charging setup, secret, or work around? Let us know in the comments below.