Adapters

[Don]

It is true that any source must be fused (or breakered) for the size of the wire downstream of the fuse in order to meet code - No argument there. It's the 'law' and for good reason

When I added the third EVSE in my garage after we bought the Chevy Volt, I planned to power it using the 6-50 outlet which is breakered at 40 amps that my wife's ceramic kiln runs off of. She uses the kiln only once or twice a year, so plugging and unplugging would seldom be a problem. One of my other EVSE's runs off a 20 amp, 240 volt outlet in the far wall used for an air conditioner. I probably only use that garage air conditioner 3 or 4 times per year and unplugging the EVSE pigtail to plug in the A/C isn't any hassle. For this latest one, I made about a 6 foot pigtail which runs from the outlet up to near the ceiling in my workshop where the kiln is located and I mounted a pair of ceramic fuse holders with 20 amp fuses for the 12/3 line which runs out into the garage to the plug for the EVSE. The installation may or may not meet the 'letter' of the code, but it's completely safe and that's the important part

If it was just a 30 amp dryer outlet, I don't think I wouldn't have bothered. Short out a 12 gauge extension cord and you will trip a 30 amp breaker or blow a 30 amp fuse almost instantly, long before the conductors in the extension cord even have a chance to get warm, let alone hot. But . . . . who is to say that someday down the road, someone might plug in a 16 gauge extension cord and have a problem?? You could maybe melt something with a lighter gauge cord. THAT'S WHY THERE ARE CODES. Things need to be safe no mater what happens and that's why the code book is full of absolute, unbreakable rules . . . . to protect the unwary from themselves

I did make a 240 volt extension cord to go with my adapter kit by buying a high quality 120 volt 12/3 cord with wire rated for 300 volts, cutting the ends off and installing L6-20 connectors on both ends. Since none of my 3 cars can draw more than 15 amps, I used L6-20 ends on all my adapters. It all began when EVSE Upgrade shipped my OEM unit back with an L6-20 plug on it. Later on, they switched to using L6-30 connectors, as they are about the same size, cost about the same but are rated for 30 amps which gives you larger connector pins, which is always a good idea. NEMA 5-15 connectors may be rated for 15 amps, but they are a poor choice for anything that will be drawing 12 to 15 amps for hours on end - No matter how new or quality the connectors are, they will get warm and eventually they will cause you problems as they age and wear

Don

[Aerowhatt]

If it was just a 30 amp dryer outlet, I don't think I wouldn't have bothered. Short out a 12 gauge extension cord and you will trip a 30 amp breaker or blow a 30 amp fuse almost instantly, long before the conductors in the extension cord even have a chance to get warm, let alone hot. But . . . . who is to say that someday down the road, someone might plug in a 16 gauge extension cord and have a problem?? You could maybe melt something with a lighter gauge cord. THAT'S WHY THERE ARE CODES. Things need to be safe no mater what happens and that's why the code book is full of absolute, unbreakable rules . . . . to protect the unwary from themselves

Don

Bad practice and only will trip in some instances. A short 12 gauge wire will trip a 30 amp circuit sure(if it is "dead shorted"). The longer it gets the dicier that gets. Which is precisely why a 30 amp circuit breaker must have no smaller than 10 gauge wire served by it no matter what. A 100ft extension cord is a is calculated as a 200 ft circuit. Most codes will require that you go to a higher gauge for a circuit over 250 ft. So a 300ft 30 amp circuit would be wired with 8 gauge wire (instead of 10 gauge). A 100 ft 12 gauge (200ft circuit) has good odds of not tripping the breaker and starting a hot mess instead (even in a best case "dead Short" scenario). Depends on the shorts character very much too, they come in a plethora of different characters. Arc faults (very common type with extension cords) will easily start a fire without tripping the breaker even in a properly wired and fused circuit. Follow the code period even if you think you know better (because you don't).

Aerowhatt

[JoeS]

Good for us to be discussing safety, and we need to be mindful that charging our i-MiEVs is considered a steady-state load which means every connector should be derated to 80% of its specified amperage. This is why 12A should be the maximum EVSE draw on a conventional 120vac 15A outlet.

High amperage can cause fires whereas high voltage can kill you. The presumption in these discussions is that the users understand what they are doing. If in doubt, ask. For example, I personally am uncomfortable with bradleydavidgood777 's intended use of a 120vac power cord with 120vac connectors on 240vac.

It goes without saying that adapters (the topic of this thread) are primarily intended to temporarily allow us to plug into an available outlet to charge up our i-MiEV while away from home. When doing that at a first-time location, after a few minutes of operation I put my hand on every connection to ensure that it's nothing more than slightly warm - preferably stone-cold - and I periodically check the connections while the car is charging if even a slight amount of doubt exists.

For my home car charging installation, my everyday i-MiEV outlet is L6-30 but I feed it using 20A circuit breakers in the breaker panel, with one permanent adapter (L6-30 to L6-20) for the EVSEUpgraded Mitsu EVSE, recognizing that the i-MiEV maximum 240vac draw is 13A.

BTW, it is my impression that the National Electrical Code addresses wiring up to the outlet but doesn't address what's plugged into it. Can anyone clarify?

[Aerowhatt]

High amperage can cause fires whereas high voltage can kill you. The presumption in these discussions is that the users understand what they are doing. If in doubt, ask. For example, I personally am uncomfortable with bradleydavidgood777 's intended use of a 120vac power cord with 120vac connectors on 240vac.

I use a similar set up for charging mine. Except I have arc fault breakers in a box between the 240V plug and receptacle where I plug in my 100 foot 12 gauge extension cord. 12 gauge 100 ft cords are rated at 13 to 15 amps depending on where they were made and where they are sold. So either is OK. It would be smarter to to use the same cord but change out the ends for 240 volt ends. Just so that anyone would know it wasn't a regular 125V cord. Bradleydavidgood777 's mentioned his cord was 10 amp. That could be a 14 gauge or even a 16 gauge in some instances. Either way, if it is a 10 amp rated cord, then it is too small for 12 amp 120V charging or 13 amp 240V charging.

Generally I would be using my set up for 120V charging at 14 amps so I left my cord standard the way it was made. In an instance where I'm using it at 240V would be in controlled environment where there would be no possible tampering by an unknowing individual.

BTW, it is my impression that the National Electrical Code addresses wiring up to the outlet but doesn't address what's plugged into it. Can anyone clarify?

There are a few specifics in the code about extensions. Mostly it is considered temporary wiring which is to variable to have specific code covering any permutation. So it is generalized (required) that "good practices will be followed". Basically the safest , smartest thing to do with extension cords etc. is to follow the code for permanent wiring as best possible. Considering the end of your cord as being the same thing as the hard wired receptacle that is tied into the breaker panel. You wouldn't be able to hardwire a three prong receptacle with 240V and meet code. So you shouldn't have the same receptacle at the end of an extension cord with 240V present either especially if it isn't protected by fuses or circuit breakers appropriate for the cords wire gauge. You wouldn't be able to hardwire a 12 gauge romex to a 30amp breaker in a permanent circuit and meet code.

Aerowhatt

[bradleydavidgood777]

The 30 amp breaker in the electrical panel will not trip due to the resistance of the too small gauge wire and length of the extension cord.
Aerowhatt

I thought 10 gauge wire could handle 30 amps. The wire inside that cord seems much thicker than what goes to my dryer.

[bradleydavidgood777]

NEMA 5-15 connectors may be rated for 15 amps, but they are a poor choice for anything that will be drawing 12 to 15 amps for hours on end - No matter how new or quality the connectors are, they will get warm and eventually they will cause you problems as they age and wear
Don

Yes and I plan on using this once a year for about 6 hours so should not get much wear.

[bradleydavidgood777]

I use a similar set up for charging mine. Except I have arc fault breakers in a box between the 240V plug and receptacle where I plug in my 100 foot 12 gauge extension cord. 12 gauge 100 ft cords are rated at 13 to 15 amps depending on where they were made and where they are sold. So either is OK. It would be smarter to to use the same cord but change out the ends for 240 volt ends. Just so that anyone would know it wasn't a regular 125V cord. Bradleydavidgood777 's mentioned his cord was 10 amp. That could be a 14 gauge or even a 16 gauge in some instances. Either way, if it is a 10 amp rated cord, then it is too small for 12 amp 120V charging or 13 amp 240V charging.
Aerowhatt

The cord is 10 gauge. Sorry if I said amp. It is very thick - I would think it can handle 30 amps no problem.

[JoeS]

Last I checked, 30A dryer cords were #8AWG and 50A oven cords were #6AWG. I think both are considered continuous service.

#10AWG extension cord should be fine for the i-MiEV, even at 100'. Let's check:

#10AWG wire has a resistance of 0.9989Ω/1000ft or 0.09989Ω/100ft
Thus, round-trip 200ft wire has a resistance of 2*0.09989 = 0.19978Ω
At 13A i-MiEV current draw, 13*0.19978 = 2.6vac voltage drop
So, instead of the ideal 120vac and ignoring connector contact resistance, the car will be receiving 117.4vac
A wire that long should have no problem dissipating 13*13*0.19978 = 33.8W

Anyone want to make some assumptions and figure out how warm it will get...?

[Don]

Anyone want to make some assumptions and figure out how warm it will get...?

I predict that . . . . it will not get nearly as warm as the 16 gauge wire which runs between the EVSE and the J-1772 connector. On all 4 of my EVSE's, that cord gets pretty warm, especially on a hot day

Don

[bradleydavidgood777]

OK so am I safe with the 10 gauge wire because that is good enough for a typical 30A dryer receptacle and I can rely on the house breaker/fuse or do I need additional breakers or fuses in the line?

And secondly, do I need to upgrade my connectors or will they be OK for the very limited use? I was figuring they are pretty beefy looking and even tho rated for 15 amps they could probably easily withstand 30A if a mistake was made. But I'm the only one plugging these things in and am going to check the cord temperature so I thought I'd be OK. But I want to be safe so a few extra bucks may be worth it. But it also adds more stuff to my kit in the car....and also, I've been using 6-20 connectors so they are only rated for 20 amps right? Again I figured those would outlast the 30 amp breaker at the house and be fine. Let me know if I'm wrong and I need to upgrade to 6-30 or whatever.

Thanks