NEMA 14-50 GFCI breaker tripping even at 18A using Mobile Connector

[P_O_Man3849]

I'll try to keep this short, but probably not...

Installed EV rated 240V NEMA 14-50 outlet right next to my breaker panel.

6/3 wire used along with suggested 50A GFCI breaker.

Using TESLA Mobile Connector, default amperage was 32A. Made it maybe 15-20 minutes and the breaker tripped. Whittled it down from 30, 28, 25, 20, 18 amps, and the most I can get before tripping is 45-60 mins.

I've searched the forums and I know others have talked about having 2 GFCI devices can cause issues but can't find the specific posts. I know the mobile connector has built in GFCI, but I wanted to be a good boy and follow code and get a GFCI breaker as well.

Should I get a regular 50A 240V breaker instead of a GFCI breaker? The garage where installed has 100A feed, and I've eliminated all unnecessary power draws trying to test this but it's still tripping.

Long story short, I think it's 2 GFCI's on the same line versus max amperage issue, but I would like others input.

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[CyberSauce]

You've pretty much perfectly described a nuisance trip. Were I to hazard a guess, the mobile connector is likely designed to leak a tiny amount of current to ground as a diagnostic. This is exactly what your upstream GFCI is meant to detect. Put a regular breaker in and be done with it.

EDIT: Yup, it's monitoring for a ground loss and it would do this by sending a few angry pixies down the ground conductor. From the Mobile Connector manual:
Charging stopped due to ground loss. The Mobile Connector detects a loss of ground.

 

[Zwick]

I bet you'll be fine with a non-GFCI breaker if you can do that. That only became code 5 or 6 years ago and the mobile connector is providing GFCI protection. I have been running that way for several years. Of course, I am out in the "boonies" where there are no code compliance inspections.

 

[HaulingAss]

I'll try to keep this short, but probably not...

Installed EV rated 240V NEMA 14-50 outlet right next to my breaker panel.

6/3 wire used along with suggested 50A GFCI breaker.

Using TESLA Mobile Connector, default amperage was 32A. Made it maybe 15-20 minutes and the breaker tripped. Whittled it down from 30, 28, 25, 20, 18 amps, and the most I can get before tripping is 45-60 mins.

I've searched the forums and I know others have talked about having 2 GFCI devices can cause issues but can't find the specific posts. I know the mobile connector has built in GFCI, but I wanted to be a good boy and follow code and get a GFCI breaker as well.

Should I get a regular 50A 240V breaker instead of a GFCI breaker? The garage where installed has 100A feed, and I've eliminated all unnecessary power draws trying to test this but it's still tripping.

Long story short, I think it's 2 GFCI's on the same line versus max amperage issue, but I would like others input.

I agree with you, it's likely an over-sensitive GFCI breaker in your panel. I say "over-sensitive" because many people use GFCI breakers with Mobile Connectors without any nuisance tripping. Maybe a different GFCI breaker (or one from another manufacturer) would fix it.

Nuisance trips are just one reason of many I recommend using hard-wired charging infrastructure instead of a NEMA 14-50 outlet I don't normally recommend going against code but this is one instance in which the GFCI requirement may have been added as a nuisance, just to throw up barriers to EV charging. It's well known that Mobile charging devices have their own GFCI protection built-in so it wouldn't need anther GFCI device upstream to be safe against ground faults.

 

[QuantumGlen]

I wouldn't use a gfci breaker on that line. Just make sure the ground connections are good.

 

[Cyberkingz]

I'll try to keep this short, but probably not...

Installed EV rated 240V NEMA 14-50 outlet right next to my breaker panel.

6/3 wire used along with suggested 50A GFCI breaker.

Using TESLA Mobile Connector, default amperage was 32A. Made it maybe 15-20 minutes and the breaker tripped. Whittled it down from 30, 28, 25, 20, 18 amps, and the most I can get before tripping is 45-60 mins.

I've searched the forums and I know others have talked about having 2 GFCI devices can cause issues but can't find the specific posts. I know the mobile connector has built in GFCI, but I wanted to be a good boy and follow code and get a GFCI breaker as well.

Should I get a regular 50A 240V breaker instead of a GFCI breaker? The garage where installed has 100A feed, and I've eliminated all unnecessary power draws trying to test this but it's still tripping.

Long story short, I think it's 2 GFCI's on the same line versus max amperage issue, but I would like others input.

Something is causing the breaker to trip... its unlikely that the charger is pulling over the breaker's rating, so that leaves us with the breaker, connection, and wire guages. If it's a new breaker this could be something silly.. I would check that the breaker connections are tight, try a different breaker since theyre rather cheap and see if you get the same result.

 

[HaulingAss]

Something is causing the breaker to trip... its unlikely that the charger is pulling over the breaker's rating, so that leaves us with the breaker, connection, and wire guages. If it's a new breaker this could be something silly.. I would check that the breaker connections are tight, try a different breaker since theyre rather cheap and see if you get the same result.

It's a GFCI breaker so it's almost certainly tripping due to the natural (purposeful) current leakage of the GFCI breaker in the Mobile Connector. And GFCI breakers aren't particularly cheap but replacing it is the best first step. Whether it's with another GFCI breaker will depend upon how important code compliance is to that install and cost considerations. It's possible another GFCI breaker will trip too. My guess is it will have a decent probability of not tripping. A plain breaker almost certainly won't trip.

 

[TraileringButtocks]

EDIT: Yup, it's monitoring for a ground loss and it would do this by sending a few angry pixies down the ground conductor. From the Mobile Connector manual:
Charging stopped due to ground loss. The Mobile Connector detects a loss of ground.

Actually, GFCI doesn't send "pixies" down the ground wire like an electron-based Lewis&Clark search party. It monitors Hot and Neutral to make sure they are equal (i.e. whatever goes into a load goes out).

 

[CyberSauce]

Actually, GFCI doesn't send "pixies" down the ground wire like an electron-based Lewis&Clark search party. It monitors Hot and Neutral to make sure they are equal (i.e. whatever goes into a load goes out).

I bet you're really fun at parties. In any case, I was talking about the mobile connector monitoring for a ground loss. The only way to detect a missing ground wire is to...drumroll please...send a bit of current down the ground. The upstream gfci will detect this.

 

[Mr Sir]

GFCI circuit breakers don't play well with transformers.

 

[P_O_Man3849]

Last night after doing more research, I disconnected the neutral pig tail wire from the GFCI breaker and capped it off. Took the 6GA neutral wire from the GFCI breaker and connected it to the neutral bussbar. Basically, it's hooked up like a regular 220 non-GFCI breaker. Set the charge to 30A and charged to 80% with zero issues.

I'll swap out the GFCI for a regular breaker just cuz, but for now it seems to have solved the issue.

I'm guessing this could account for a lot of people giving up on the mobile charger and just getting the wall charger to avoid the nuisance trips.

I will probably get the wall charger at some point, but a properly working mobile charger is more than sufficient for my daily driving.

Thank you all for your replies, I appreciate the assistance!

 

[mongo]

Last night after doing more research, I disconnected the neutral pig tail wire from the GFCI breaker and capped it off. Took the 6GA neutral wire from the GFCI breaker and connected it to the neutral bussbar. Basically, it's hooked up like a regular 220 non-GFCI breaker. Set the charge to 30A and charged to 80% with zero issues.

I'll swap out the GFCI for a regular breaker just cuz, but for now it seems to have solved the issue.

I'm guessing this could account for a lot of people giving up on the mobile charger and just getting the wall charger to avoid the nuisance trips.

I will probably get the wall charger at some point, but a properly working mobile charger is more than sufficient for my daily driving.

Thank you all for your replies, I appreciate the assistance!

The mobile connector doesn't use the neutral wire, so that mod shouldn't have had any effect. Are neutral and ground correct at the 14-50 receptacle?

The variable trip times (longer charge at lower current) sound more like breaker overheating than GFCI. Potentially, the neutral wire should have helped dissipate heat from the breaker.

 

[HaulingAss]

The mobile connector doesn't use the neutral wire, so that mod shouldn't have had any effect. Are neutral and ground correct at the 14-50 receptacle?

The variable trip times (longer charge at lower current) sound more like breaker overheating than GFCI. Potentially, the neutral wire should have helped dissipate heat from the breaker.

True, the Mobile Connector doesn't use the neutral wire, but I believe the NEMA 14-50 outlet is required by code to have one. And I image the GFCI breaker protects against current leakage on both sides of that circuit. So maybe the outlet, or the wire to the outlet, has some leakage?

 

[mongo]

True, the Mobile Connector doesn't use the neutral wire, but I believe the NEMA 14-50 outlet is required by code to have one. And I image the GFCI breaker protects against current leakage on both sides of that circuit. So maybe the outlet, or the wire to the outlet, has some leakage?

Right, a 14-50 has ground and neutral. I was trying to reconcile bypassing neutral in the GFCI with not tripping. Either the manipulation involved improved a loose connection, or neutral was channeling current to/from somewhere.
I was thinking having ground and neutral swapped at the outlet might explain the behavior change, but now that it's after lunch, that doesn't make sense because running ground through the GFCI would theoretically avoid tripping due to filtering and ground continuity testing.

So I'm sticking with the idea of a bad connection leading to breaker overheating and tripping.
Unless they are swapped and neutral was also connected to ground via the box wiring and weirdness ensued...

 

[REM]

I have installed many NEMA 15-50 circuits for EV charging and never used a GFCI specifically for this reason. You should be just fine with a regular breaker.

important to note that you absolutely should be properly torquing electrical connections. This is especially important for circuits above 20 amps. You should be using a torque driver (or appropriately sized torque ratchet).

also a really good idea to inspect new circuits under load with thermal cameras if you can.

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