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GFCI Breaker is Code for EV Charging
- Thread starter caffeinated
- Start date
You're oversimplifying and therefore not correct. Every Tesla car comes with a plug adapter for the UMC that can be used with 5-15 receptacles. Those are the standard 120V outlets in your house. What is the voltage on? Yes, it's on one hot side and one neutral side to make that 120V. So yes, the UMC does use neutral if that is one of the lines forming the circuit.
So more accurately, the UMC just has two pins to look at to measure the voltage for the circuit. It will very easily detect and use whether it is 120V or 240V--it doesn't care. A GFCI check is not specifically only on neutral. It is looking at the two lines that make up the circuit and makes sure that the same amount of current is going in/out on those two wires. If it is uneven between them, then that means some of the current is leaving through some other path, and that's what is dangerous and will trip the GFCI. So for 120V circuits, that is Hot and Neutral. For 240V circuits, it's Hot1 and Hot2.
sleepydoc
Well-Known Member
See what @Rocky_H wrote above. To expand on that, the ground and the neutral are at the same potential and GFCI receptacles can also be used as a substitute for a grounded receptacle in locations with older wiring where no ground is available. They work by comparing the current in the two legs of the circuit. If there’s an imbalance they trip; it doesn’t matter whether where the imbalance comes from.
Not going to jump in the debate to GFCI or not, but on vaca at my parents house and plugged in to an exterior out let that is GFCI and at 12A it trips the circuit. Put it down to 11A and was fine. There was absolutely no other load on this circuit other than the car and the breaker is a 20A breaker.
12A charge sucks but 11A but blowssss
12A charge sucks but 11A but blowssss
sleepydoc
Well-Known Member
If the breaker is tripping and there’s truly nothing else on it then it sounds like an issue with the breaker. You can try swapping out the breaker if you’re comfortable doing so. The other thing you can do is convert it to a 220V circuit IF there is only a single receptacle on the circuit. This will double the power but you can only do this if there are no other outlets on the circuit! If you are not 100% sure then I would leave it at 110.
How certain are you that there was nothing else being powered on the circuit? You would have to use an ammeter or turn off all of the other breakers and check the utility meter.
I'd be concerned that an unused outlet, or a device that wasn't using power at the time of the test might be missed.
I'd turn off the one breaker and check all lights and outlets to verify that nothing but the one outlet in question turned off before switching it to 240.
Similar to jcanoe's approach, you could use an ammeter on that one circuit when not charging as a double check, but will still miss unused outlets or idle/low power devices.
As an electrician, i wouldn’t not convert a 120v to a 240v outlet unless ut was patently obvious it was a dedicated circuit. Just not worth it.
sleepydoc
Well-Known Member
Agreed - that's why I tried to be pretty strong in my warnings/caveats. If it's in a place where you can trace the entire circuit and see that it only goes to that one outlet in the garage then I'd be comfortable with it. otherwise it's far safer to run a new branch circuit.
Most modern Electric Vehicle Supply Equipment (EVSE), or EV chargers, have built-in GFCI protection. When the unit is hardwired, there is no need for a GFCI breaker. If the unit is installed with a plug with a GFCI breaker, there can and will be faulty trips.
Most modern Electric Vehicle Supply Equipment (EVSE), or EV chargers, have built-in GFCI protection. When the unit is hardwired, there is no need for a GFCI breaker. If the unit is installed with a plug with a GFCI breaker, there can and will be faulty trips. Check with dealer to be sure. Cable height when charging should not be in contact in pooled water. Check with Tesla, sec NEC 645 “https://www.nema.org/searchresults?&searchQuery=Ev&wordsMode=AllWords”. I’m having an emergency cut off switch put in for my 240, 60am, single phase line.
False trips of a GFCI breaker may or may not occur. GFCI breakers are available that have a slightly less sensitive threshold for tripping.
The built-in GFCI in the EVSE protects the user when plugging or unplugging the charging cable from the vehicle.
The 2017 NEC requirement for GFCI protection for the receptacle for an EV charging circuit is there to protect the user when plugging or unplugging the EVSE equipment from the outlet.
In my experience every EVSE owner's manual states that you should always turn off the power at the breaker before plugging or unplugging the EVSE from the outlet. This step mitigates any risk of electrocution while plugging or unplugging the EVSE. If people bothered to read the manual, followed the instructions there would be no need for the separate GFCI for the receptacle.
davewill
Active Member
That didn't sound right, so I checked the Tesla Mobile Connector Gen 2 Owner's Manual and sure enough, it gives no such instruction. Here is what it says:
The Tesla Gen2 Mobile Connector is designed to work with a wide selection of power plug adapters. The photo shows a NEMA 5-15 receptacle (120V) and power plug. I should have clarified that the EVSE owner's manual for the EVSEs I currently own or have owned state that the owner should turn off the circuit breaker for safety when plugging or unplugging an EVSE from a 240V receptacle.
• For personal safety, the circuit breaker MUST be turned off prior to plugging in AND/OR unplugging 240V appliances
(including this EVSE.)
See Page 7:
https://cc-wp.b-cdn.net/wp-content/uploads/2022/04/HCS-Standard-Manual-V21-FINAL-20220406.pdf
davewill
Active Member
Well, that's for a ClipperCreek EVSE. The Tesla manual has no such instruction.
My post was in response to the statement "Most modern Electric Vehicle Supply Equipment (EVSE), or EV chargers, have built-in GFCI protection.", not regarding what Tesla states in the Gen2 Mobile Connector Manual. Perhaps Tesla assumes that the 240V circuits/receptacles are up to date with GFCI protection per the 2017 NEC.
The note regarding turning off the power at the breaker for any 240V circuit prior to plugging or unplugging the EVSE appears in every ClipperCreek owner's manual.
davewill
Active Member
I see you updated your post to clarify that you were not necessarily referring to the Tesla MC. Your point was that if people would just read the manual, they would turn off the breaker and wouldn't need GFCI, but as you can see, EVSE manuals do NOT, in general, say to turn off the breaker.
Note: I searched and downloaded a few other manuals. Some said to turn off the breaker and some didn't. The ones that said to turn off the breaker seemed to be ones, like the ClipperCreek, that also come in a hard-wired model or had a hard-wired install option.
I have installed gfci breakers on numerous EVSE installed and have yet to see a single instance of nuisance tripping. Stop yer bitching and put the gfci in like you were told.
The cords on the live side of the evse might be damaged not to mention the proliferation of evse extension cords..
The cords on the live side of the evse might be damaged not to mention the proliferation of evse extension cords..
sleepydoc
Well-Known Member
Completely agree. I also have a saltwater fish tank and people make the same claims there to justify not using GFCI receptacles. I have never had a GFCI nuisance trip in all my years of using them. It's kind of like people saying they don't want to wear a seat belt because they wouldn't be able to get out of the car in time if it plunged into a lake.
ai4px
Wes
The EVSE does it's own GFCI test. The *only* risk to you is plugging something in to the 14-50 and slipping your fingers around the plug to the blades. 14-50 plugs are not intended for daily plug cycles, so plug it in and forget about it.
