Extension cord recs when there’s no info on outlet

1) Toyota warns you against using any extension cord.
2) if it is a 110 volt outlet, it is almost assuredly 15 Amps. It is not assuredly a GFCI outlet as it should be to safely protect humans while you charge your Prius.
amazon.com/Receptacle-Power-Outlet-Socket-Tester/dp/B01IR2OZ7Q
3) the thicker (lower number gauge) the extension cord the better.
amazon.com/dp/B01IN11IJ4/ref=twister_B01N5Q9SSB?_encoding=UTF8&psc=1

Can you photograph the receptacle and post the picture here?

15 amp 110 volt receptacle with polarity

 

I would expect it to be a 20 AMP circuit and be GFI, garages are suppose to be GFI according to the National Electric Code. The maintenance guy should be able to tell you where the breaker is and it will have the amperage marked on it. For a short run inside the garage whether it is a 15 or 20 amp circuit I would use a number 12 gauge extension chord, it is rated for 20 AMPS. I don't know what your car requires.

The trouble is there may be other loads on this I am assuming a branch circuit with other outlet so you may not be able to draw the total rated load from the circuit yourself. It's all in the details. It would be nice to have a dedicated circuit just for your car.

 

Not knowing if there is another load on that particular circuit, i wouldn't put a car load on it not knowing what else is there...as previous posts indicate...a #12 extension cord would be rated at 20 A would be required...The car itself would pull 12-16A when charging...the car can be set down to 8A draw but the time to charge increases...
More than likely the plug is 120-140V AC rated for 20A...so putting your car on there, and somebody else has a 10A draw on it would overload it and pop the breaker somewhere...

 

@JimboPalmer and @wb9tyj make excellent points.

Some may say otherwise, but I’m afraid there isn’t one. Especially in an apartment building, where others might be at risk if something were to go wrong, you really should have an outlet (installed by an electrician, if necessary) that you can use for charging without an extension cord.

As much as I’d like to offer a practical solution, I urge you to consider your liability exposure and the provisions of the electrical code that require the instructions for equipment to be followed (NEC 110.3(B)), prohibit using extension cords as a substitute for the fixed wiring of a structure (NEC 400.8(1)), and limit the total charging cable length, from outlet to car, to 25 feet (NEC 625.17(C)).

Please don’t take this the wrong way, but if you don’t have the electrical knowledge to identify an outlet from a distance (most aren’t marked, by the way) and select a suitable cord, you also aren’t in a position to ensure that the installation is otherwise safe.

Voltage - Energy Education
Current - Energy Education
Wire gauge - Energy Education

If you’re looking for something more in-depth, the Navy Electricity and Electronics Training Series is often mentioned as a good self-study course.

 

A personal example:

When I got my Fiat500e, I plugged the 120 Volt, 12 amp EVSE into my garage’s 20 amp circuit. No problem for the first 3 - 4 days, then my wife plugged in her 1875 watt / 125 Volt (15 amp) hairdryer! Popped the circuit breaker. For the next month we would coordinate between charging, and hair drying. We finally got a level-2 EVSE installed. You really need to know what else is on that circuit.

 

Just sayin cause
after bout 10 years of hearin "it popped again", I finally have to rewire the outside outlet and floodlight above + it's leadin, which mean removing siding.
Long story short, I have 2 count um, 2 gfci outlets on the circut which feed the 1 outside outlet, basement washer/gas dryer and bathroom remodel job. I really should have split that circuit a LONG LONG time ago, when I repaired the outside outlet. I was "agassed" when I noticed the outlets feed a few weeks ago. I can't believe I didn't notice or didn't want to dig any deeper into it 20 years ago when I replaced the 3 outlets and floodlight switch,

 

I've recharged successfully with a 25 foot 12/3 extension cord (bought from Amazon, for some reason posting the link results in just a blank space ).

 

amazon.com/dp/B01IN11IJ4/ref=twister_B01N5Q9SSB?_encoding=UTF8&psc=1
Is still a good choice. I do not think you will find a 10/3 cord.

Edit: I am wrong
amazon.com/dp/B01M0HQBXT

 

The Prime EVSE will not draw more than 15 amps (I think it's spec-ed to draw 12, or 6 if you limit it from a car configuration menu). So you should be OK.

 

Try home depot
They have a 25 foot extra heavy duty, 10 gauge.
Rated for circular saws and air compressors.

 

Just my opinion, I would have enough length so that it would reach from the front of the car or the back, or in the next adjacent parking spot (if there is one). Give yourself room to wiggle.

 

The shortest practical length is equally as important as using a heavy gauge. The voltage loss along the cord is a product of wire resistance (per foot) times length.

With a proper heavy gauge cord, not tightly bundled or coiled, this should not be a problem. But a cord short enough to not need coiling (or more than two or three turns) is better still, and will reduce the cord's voltage loss.

 

I made my own extension cords to ensure I had top quality connections and specs. Cost me about $50 each (i made 2 of them). I've been using 1 every day to charge at home and have had no issues.
Posted my cord and specs in this thread.
Longer Charging Cable? | Page 2 | PriusChat
Overkill is better safe than sorry here!

 

For our purposes, you can think of 15 Amps as the shape of the plug.

It is very likely your out let resembles the top one, rated 15 amps.



Thick wire just means less heat in the cord and more power makes it to the end of the cord.