Using a NEMA 10-30 Dryer Cord

I tried to search for this topic and did not find it, but that could be because the search terms for it are far too common to isolate.

I rented a Nissan Leaf to use this past week while travelling and anticipated a need to charge with 220v without installed L2 chargers available. The Leaf had an EVSEUpgrade unit (although it is a very early unit, which becomes important later), so I could use it to charge if I got access to 220v. The owner did not have any other plug adapters than the standard household NEMA 5-15, however.

Being an engineer, focused on materials, I thought to myself- If I do not exceed the current capacity of the conductor nor the insulating ability of the insulation, then there's no reason I couldn't put 220V though the NEMA 5-15 plug, right? Yes, true in theory and in practice, although not code-compliant or mom-approved. I made this to take on my trip with me:


That's a NEMA 10-30 dryer cord with a NEMA 5-20 connector.

Now, why didn't I just use a L6-20 instead? Well, because I wanted to be able to use a normal 12AWG extension cord if/when my hosts' dryer plug was farther away than the stock EVSE reach plus the 6ft dryer cord, without making up a special L6-20 extension cord.

I report that this DID work, albeit with caveats. I ended up not needing to L2 charge much, and this did allow that- but heated up in an uncomfortable manner. After an hour, the NEMA5-15 connection between the extension cord and the EVSE pigtail was too hot to hold onto, and I terminated the L2 charge at that point, going down to L1. The reason is that the pigtail I had was 14 gauge wire with the standard NEMA 5-15 connector, and the EVSEupgrade was drawing 16 amps. Remember how I said it was a very early model? The earliest ones appear to be non-programmable. (Correct me if I'm wrong) If I could have , I'd have simply programmed it for 12A and I predict that this setup would have worked just fine, even if it would make code inspectors flinch. However, since it was drawing 16A, it was drawing ~106% of the components' rated capacity as a constant load, and was unsafe for prolonged use.

The 12AWG extension cord was mildly warm, but fine, even coiled up.

I say all that to say- if you have an old, non-programmable EVSEupgrade- yes, this has been tried, and no, you shouldn't do it. If your EVSEupgrade is programmable, though (as I understand that the vast majority are), this may be something to be experimented with. At your own risk, of course. I did this for a week's rental of a Leaf, but if any owner were to attempt this, it'd be worthwhile to simply make a dedicated L6-20 (or L6-30) extension cord.

Has anyone else tried this?

The early ones were not programmable and were fixed at 12 amps. I had one.

The one I had was labelled 12A @ 120v, 16A @ 240v. I actually had a clamp-on ammeter with me but didn't check actual current draw since it requires a single conductor to be isolated.

Not sure why you thought that 16A continuous load wasn't going to exceed the capacity of a 5-15 socket, with 14ga wire? Maximum continuous load should be no more than 80% of the rating.

Also, if you're going to use an extension cord, don't coil it.

I hatched this plan before I knew the EVSE I had to work with was non-programmable. My plan had been to program the EVSE down to 12A, which I think would have been fine. However, once I got there and discovered it was fixed, I decided to give it a shot and monitor how long it would take to heat up. These are the results.

Hopefully you took that cord apart as soon as you finished your trip.

nedfunnell said:

I hatched this plan before I knew the EVSE I had to work with was non-programmable. My plan had been to program the EVSE down to 12A, which I think would have been fine. However, once I got there and discovered it was fixed, I decided to give it a shot and monitor how long it would take to heat up. These are the results.

Click to expand...

Ah, that makes sense. Wasn't clear to me at first.

The very first upgrades were 12a@240v. Later he came out with "Rev 2" which was 16a@240v, both non-programmable. Around 2013, when the new cars came with a new model EVSE, he came up with the programmable version he's selling now.

I used to carry one of these around with my Rev 2:

http://www.stayonline.com/detail.aspx?id=14863" onclick="window.open(this.href);return false;



It is 50 ft. with 12 gauge wire and molded plugs. It's rated for 20a@250v. Yes, it's pricey, but you wouldn't save more than $20 or so buying the parts at the local Home Depot and going DIY, well worth the difference to me.

As you found, there are a number of problems with the route you took. First, the 5-15 is only rated for 15a@120v. Second, many 5-15 extension cords only have 14g or even 16g wire in them. Finally, using any old extension cord is likely to expose you to a worn plug or socket that won't make solid contact. Better to carry your own gear that is a known quality.

davewill: You could also add that any "old (heavily used?) extension cord" may due to repeated flexing over the years have broken strands ( i.e. higher resistance) at any point in its length (although most likely near its two ends) which can overheat (and which you cannot see, but may be able to feel) and lead to insulation failure.

Also we are all subject to the possibility of poor judgement due to a number a number of factors including old age and senility. IMO the more idiot proof electrical devices are, the better they are.

You could have plugged the EVSE directly into the proper plug and used a JLong J1772 extension cord.

Then, all the safety of the J1772 standard is present throughout the extension cord (GCFI, pilot signal, proximity signal), plus it won't get hot (40 amp rated).

2011-2012 Leafs charge at 12A at 120V regardless of pilot setting above 12. The rev 2 EVSE upgrade was non programmable and spits out 16A regardless of voltage. Just an FYI if someone tries to use a rev 2 unit on 120V with a 2013 or newer- it will draw 16A on 120V.