GFCI Trip on Plug in (spare connector)

[daniel]

So what happens if someone uses the 240-volt 40-amp mobile connector at an RV park? For that matter, how do RVs avoid similar issues at RV parks? Presumably the outdoor outlets at RV parks have to have GFCI, and whatever considerations require the mobile connector to have GFCI would require the same for an RV. No???

I've had my Roadster for just over a week and have only ever charged at home where I have an RV-style outlet but without GFCI. I don't know why there's no GFCI. I asked the electrician to put an RV outlet on a dedicated circuit and it never occurred to me to ask about a GFCI. (That circuit was for a Porsche EV conversion project that keeps getting delayed.)

I don't anticipate any trips long enough to require charging away from home. Any trip that long I'd probably want the luggage space of the Prius. But I'd like to know whether such charging is a reliable option. I've read of people doing this. So how do the issues relate to the OP's problem?

[DaveD]

As far as I know, RV 240V connectors do not have a GFCI on them.

[ChadS]

I've used a lot of 14-50 (240V 50A) connectors at campgrounds, and don't ever recall seeing GFCI or having a problem using them.

There are 14-50 connectors with GFCI in the World Trade Center parking garage in Portland, and those trip when I try to use my RFMC with them. (Fortunately they also now have an HPC there).

[S-2000 Roadster]

Presumably the outdoor outlets at RV parks have to have GFCI, and whatever considerations require the mobile connector to have GFCI would require the same for an RV. No???

I've had my Roadster for just over a week and have only ever charged at home where I have an RV-style outlet but without GFCI. I don't know why there's no GFCI. I asked the electrician to put an RV outlet on a dedicated circuit and it never occurred to me to ask about a GFCI.

I'm fairly certain that your electrician would have installed GFCI if it was required by code. Granted, there are some flaky people in the world who'll take your money without doing a complete job, but in this case I assume that he did everything required by law.

Leave it to the government to require GFCI on outdoor 120V outlets but ignore outdoor 240V outlets at the same time. Similarly, I'm not surprised that the government-mandated 120V GFCI causes so many problems that things don't even work.

Note that RV parks appear to universally have breakers next to every 240V outlet, so perhaps it would be completely redundant to require GFCI on them. A properly-wired receptacle that is done "to code" should have no ground fault, otherwise it wouldn't be safe. On the other hand, considering all of the strangely-wired RV adaptors that have been discussed on this forum, I wouldn't be surprised if any such GFCI would trip all the time.

[W.Petefish]

240v connections can have GFCIs, they are just less common. (What do you think is in your UMC besides some signaling circuitry?)

Removed the GFCI from the "spare connector" and put an extension cord end on it. Then took a piece of 12-3 SJOOW wire (available from Home Depot) and put the GFCI on it with a female extension cord end on it. Works great now.

[daniel]

I'm fairly certain that your electrician would have installed GFCI if it was required by code.

Yes, I'm sure he would.

Leave it to the government to require GFCI on outdoor 120V outlets but ignore outdoor 240V outlets at the same time.

Yep. Weird. I just didn't know that.

Note that RV parks appear to universally have breakers next to every 240V outlet, so perhaps it would be completely redundant to require GFCI on them. A properly-wired receptacle that is done "to code" should have no ground fault, otherwise it wouldn't be safe.

A GFCI and a breaker do very different things: The breaker protects the wiring from excessive current. A GFCI protects you in case you touch a live wire and current flows through you to ground. That could kill you long before a breaker would trip.

(What do you think is in your UMC besides some signaling circuitry?)

I really had no idea what's in that thing. My Zap Xebra plugs directly into the wall with an extension cord, and that goes directly to the charger in the car. I've never understood why the Leaf and the Tesla require an EVSE or UMC.

[S-2000 Roadster]

A GFCI and a breaker do very different things: The breaker protects the wiring from excessive current. A GFCI protects you in case you touch a live wire and current flows through you to ground. That could kill you long before a breaker would trip.

It's more complicated than you describe, but you are correct that I oversimplified things in my comment.

A breaker will protect both the wiring and you, provided that the current exceeds the limit that is designed in. If you touch a live wire on a NEMA 14-50 and current flows through you to ground, then it will still trip the breaker if that current exceeds 50 A. I suppose you could be electrocuted on less than 50 A, assuming some kind of resistance prevented the current from exceeding that level, and the breaker wouldn't do a thing to help in that case. A breaker doesn't really distinguish between protecting the wiring and protecting you, it merely detects current flow.

Safety grounds are part of the above scenario, though, and they should not be ignored.

Traditionally, any electronic product which includes live wires that could potentially electrocute are enclosed in a metal chassis that is connected to the safety ground. That way, if a live wire comes loose, it will short out to the metal chassis and the low resistance of the safety ground will pull nearly infinite current, tripping the breaker as quickly as possible. Breakers will protect against electrocution and fire, but only provided that the safety grounds are also installed according to code.

These days, many electronics are housed in plastic casings, making the traditional grounded chassis impossible. Also, there have been many violations of wiring codes over the years, so it isn't exactly safe to assume that a safety ground is present everywhere that one should be. GFCI is an attempt to detect errors or faults in the required safety ground wiring, which is especially important when you consider that a breaker may not function properly without the required safety ground.

Unfortunately, detecting a ground fault is way more complicated than detecting a current that exceeds a threshold, and thus we are stuck with the side effect that redundant GFCI circuits will trigger each other and refuse to allow operation even in proper conditions.

I really had no idea what's in that thing. My Zap Xebra plugs directly into the wall with an extension cord, and that goes directly to the charger in the car. I've never understood why the Leaf and the Tesla require an EVSE or UMC.

I assume that the ZAP Xebra only plugs into 120 VAC outlets, with a maximum current of 12 A or perhaps 15 A at most. That's a fairly simple circuit, but its charge rate is severely limited compared to the Tesla.

Even if the ZAP Xebra is compatible with 240 VAC, it's still possible to make a very simple circuit which accepts basically any voltage at any frequency and pulls a mediocre amount of current. The disadvantage here is that such simple and cheap circuits allow sparks during connect or disconnect, which degrades the electronics over time. Also, the charge rate is still limited to the lowest common denominator.

... not to mention the fact that the ZAP Xebra batteries will in no way last as long as the Tesla battery simply because the charging system is not nearly as intelligent.

What Tesla Motors has done is design a charging system that can safely scale from 12 A @ 120 V (1,440 W) all the way up to 70 A @ 240 V (16,800 W). That's a very significant feat, especially the safety aspect. In order to save Tesla owners from earning an electrical engineering degree before they charge their vehicles, the requirements are that the power source have intelligent signaling so that the car knows when it is safe to pull 70 A versus when it is only safe to pull 12 A, and various levels in between those extremes.

Tesla convinced the SAE to use their intelligent signaling, and thus the Leaf has similar requirements.

Basically, you can have easy, simple and cheap, or you can have easy and high performance, but you can't have high performance, simple and cheap without giving up the 'easy' part.

[Doug_G]

A breaker will protect both the wiring and you, provided that the current exceeds the limit that is designed in. If you touch a live wire on a NEMA 14-50 and current flows through you to ground, then it will still trip the breaker if that current exceeds 50 A. I suppose you could be electrocuted on less than 50 A, assuming some kind of resistance prevented the current from exceeding that level, and the breaker wouldn't do a thing to help in that case. A breaker doesn't really distinguish between protecting the wiring and protecting you, it merely detects current flow.

You don't need anywhere near 50A to electrocute someone; that much power would cook you. The reality is that your body is not conductive enough to get anywhere near 50A through it, at least without a heck of a lot more voltage.

The primary electrical risk is electrical currents going through your heart - they can cause it to stop. It doesn't take very much current to do that; fortunately it takes a little bit of work to get that current going through your body.

Batteries can provide a lot of current, but they won't kill you because the voltage is too low. It's the voltage that makes a circuit dangerous. 28V won't electrocute you. 110V could kill but it's actually pretty rare; you have to be very unlucky or very stupid. On the other hand 240V is pretty dangerous.

Aside from wearing rubber soled shoes, the standard safety tip when working on things with high voltage, such as old-fashioned TV sets, is to keep one hand in your pocket. One hand on a high voltage and one hand on ground is a killer, as the current goes right by your heart.

These days, many electronics are housed in plastic casings, making the traditional grounded chassis impossible.

Yes but the electrical code requires that those devices be double-insulated, so it takes more than a single point failure to cause a dangerous situation. The safety certification also typically requires every device manufactured to go through a Hi-Pot test, to make sure there's no leakage.

The electrical code is also the reason why 240V charging requires an external device. Strangely they don't require that for an RV. It's either grandfathered, or it's simply a matter of numbers. They probably figure that many more people will be handling 240V for car charging.

[daniel]

My understanding, and someone can correct me if I'm wrong, is that while a circuit breaker detects excess current, a GFCI detects imbalanced current: more current going out than coming back, which means there is leakage to ground. Also, it is my understanding that a GFCI will trip much faster than a circuit breaker.

As for the Xebra, it has an aftermarket LiFePO4 battery pack and matching charger. It draws 25 amps at 120 volts. The EV Porsche, however, (which was sort of operational for a month before it went in to another shop to be fixed from the original botched conversion job) charges off an RV-style circuit: 240 volts, 50 amps, though my understanding is that it only draws 40 amps. IOW it draws the same as the Roadster when the Roadster is on the UMC. In fact, I had the circuit installed for the Porsche. It was fortuitous that it's perfect for the Roadster as well. The Porsche, like the Xebra, plugs directly into the wall and that connects directly to the charger. But unlike the Roadster, neither the Porsche nor the Xebra can plug into anything but their respective design circuits.

[TEG]

Yeah, I think you are right. I think the point of the GFCI is to detect if there could be some current flowing through a body, and to try to shut off the power before it harms them.
So, it has to be sensitive to "leaks" and respond quickly.