Extension Cord

I can only suggest, as I have to others in the past, that you follow Toyota’s warning and the National Electrical Code. In practice, safe use of an extension cord depends on both the cord’s characteristics and how it is used; see the code’s general prohibitions.

 

One option to get around extension cord limits is to set the charge rate to the slower current choice, which I seem to remember as 8 amps. This causes a longer charge time, but reduces electrical stresses and losses in the wiring and may allow you to get by with longer extension cords.

 

overkill. just read the extension cord threads and pick one that has enough gauge for the length you're running.
toyota legalese not withstanding, use common sense and you'll be fine

 

Not supposed to. BUT. I have to use a Heavy Duty Air Conditioner 20 AMP cord that is 4 FT long to reach the outlet at work. No issues after 8 Months of Daily use. No tripped beakers or issues.

Steve

 

That sounds like a good extension cord. You'll be fine as long as you keep the cord in condition. And don't coil it up while in use (it can get too hot).

GFCI on the cord sounds like overkill if you use a GFCI outlet, since there is also another GFCI inside the EVSE. It won't hurt anything to have too many, but 3 GFCIs sounds overly redundant.

There is a good reason to use extension cords with built-in GFCI, but I can't remember right now. Probably just for use with non-GFCI outlets, since a cord is likely to be sitting on the ground which might be wet.

 

I've been using a 12-gauge 100' long extension cord (yes, it's that much distance between my house and my parking space) since September, with no problems so far. I put a cover on my outdoor outlet, and a water-resistant cord lock on the end to protect the connection between the cord and the charge cable. There is a bit of a voltage drop over the distance, but so far there's no sign of excess heat anywhere along the line when pulling 12A.

 

Less than 10 feet (100 inches) should not be an issue. If you have a measurable voltage drop over that distance then something is seriously wrong.

 

Corrected my post - it's 100 feet, not inches.

 

i read it as feet

 

@PushingSquares I use a 50' 12 gauge cord and yeah there's a bit of a voltage drop, but that's going to be present no matter what. I think a fair bit of household wiring is 12 or 14 gauge anyway. I'll have to dig to confirm but pretty sure that the charging port would work with 100 V (Japan), 120 V (US/Canada) and 240 for everything else. Aside from some loss in efficiency, 50'...100' probably a non issue even with lower gauge cords, just more voltage drop. You probably won't notice any heating up unless you get some really cheap and long cord.

I also noted last fall, before it got cooler, that charging in the afternoon I would notice the wattage would be lower in the heat of the day versus in the evening...seems the sun heating the charging cable up is enough to incur some higher resistance and thus voltage drop.

 

IIRC current code is minimum 14 gauge or better for a 15A outlet, 12 gauge for 20A. So yes, a 12 gauge extension cord might be a bit of overkill, although it does make the voltage drop lower.

 

keep in mind that house wiring is solid, and extension cords stranded

 

I believe that is taken into account in the wire gauge sizing. @jerrymildred our resident electrician can confirm.

 

That's right. Besides the wire gauge, the type of insulation is another factor. Also, of course if it's aluminum or copper wire.

For example:


In our factories, we used THHN wire, which is supposedly good for 24 amps with #14. But that's at an ambient temperature of 86F with only three wires in the raceway. We always derated them and used the next size up since it was always hot in there and we typically had way way more than three wires in a raceway or conduit.

When using an extension cord for my PiP, I have a 10' one and a 25' one, both of which are #12. I like my wires a little on the heavy side.

 

I'm using this one to charge the Spark right now.
RIDGID 50 ft. 10/3 Heavy-Duty Contractor-Grade Indoor/Outdoor Extension Cord-HD#729-706 - The Home Depot

 

Assumes no resistance in the plugs and their attachments to the wires at typical temperatures.

Resistanceohms)

10 AWG is 0.0100/10 ft.
12 AWG is 0.0160/10 ft

Using V=I*R and assuming 12 Amps for PP

Volts (per 10 ft)
10 AWG: 0.12
12 AWG: 0.192

Power lost = I^2*R
Power lost(per 10 ft) in Watts
10 AWG: 2.3
12 AWG: 1.44

So to reaffirm earlier comments, 10 feet cords really don't matter much between 10 and 12 AWG. At 100 feet you are throwing away about 9 watts out of the total 1440 watts provided by the outlet. (0.6%) This is still not too much heat being generated.

Bottom line, up to 100 feet, the 12 AWG cord is sufficient assuming it is in good condition. Use UL rated outdoor cords for this purpose. Also, do not plug one cord into another to make a longer connection. The plugs add additional resistance, places where moisture can enter and most importantly a place where heat can be generated and a possible fire caused.

Note that I pulled the the resistance numbers from: AWG American Wire Gauge Diameter and Resistance

 

I currently do not a GFCI on the 120V outlet I'm using. If there is a GFCI inside the EVSE do I need to switch the receptacle out for a GFCI? Thanks.

 

The GFCI protects you when handling the EVSE downstream of the controller box, such as when plugging the handle into the car's charging port. The one in the wall outlet protects you when plugging the EVSE into the wall. The one in the EVSE won't sense a ground fault upstream of itself. It's a low probability that you'd get hurt (especially if it's in the garage or other normally dry place), but it is a real one.

 

Shouldn't 12 AWG wire lose more wattage per foot than 10 AWG?