2 Model 3s Tripping Circuit Breakers

[johnathanchick]

Hello,
First post! This is an electrical question more out of curiosity -- I will have a certified electrician/contractor come out to investigate, but wanted to pick the forum's brain while waiting.

I am living in a backhouse/ADU with my own dedicated electrical panel/system. My house is fed from a separate feed with its own meter (junction box at owner's house, so I assume it tee-s in there, or maybe I have my own feed... not sure).

The garage is shared with the home owner and her garage is tied into her panel.

Regardless, we both have Tesla Model 3's. Everything has been fine (place is only 2 months old). Charging was working up until yesterday afternoon without a problem.

Last I was unable to charge my car. My car charges for about 30 seconds then the breaker trips. Owner mentioned that hers has been doing something similar. Additionally, she is also unable to charge with a 120V outlet -- trips breaker. I haven't tried that yet.

I felt the breaker in my panel after it tripped and it was warm.

Any idea? I am using a 20A breaker (dont know the wire size -- assume its code compliant since its brand new) with a 6-20 adapter. I have a few other "larger" circuits in my panel (30As) and those have been working fine.

 

[Midnightsun]

Is this a dedicated circuit for charging only? If not there may be something else on the circuit which turns on or being used which can easily cause the circuit to trip when charging.

 

[johnathanchick]

I will verify with the contractor that it is dedicated. But I am 99% sure yes. It is "labeled" as car charger in the breaker box. Whole thing is weird to me since there haven't been any issues up until now and landlord and I are having the same issue.

 

[LincolnsDoctor]

Maybe try reducing the charging Amperage?

When I was charging with 120V the breaker would trip whenever it was too hot out, or the sun was shining directly on the charging cable. Or someone used a hair dryer

 

[jrweiss98020]

Set the max current for charging via the phone app. Try 10 or 12A at first, and see how it does.

 

[johnathanchick]

Thanks for the suggestions!
Ironically, I tried charging this morning with no modifications and everything is working fine.

Maybe there was a power quality delivery issue last night?

 

[Don.Church]

Hello,
First post! This is an electrical question more out of curiosity -- I will have a certified electrician/contractor come out to investigate, but wanted to pick the forum's brain while waiting.

I am living in a backhouse/ADU with my own dedicated electrical panel/system. My house is fed from a separate feed with its own meter (junction box at owner's house, so I assume it tee-s in there, or maybe I have my own feed... not sure).

The garage is shared with the home owner and her garage is tied into her panel.

Regardless, we both have Tesla Model 3's. Everything has been fine (place is only 2 months old). Charging was working up until yesterday afternoon without a problem.

Last I was unable to charge my car. My car charges for about 30 seconds then the breaker trips. Owner mentioned that hers has been doing something similar. Additionally, she is also unable to charge with a 120V outlet -- trips breaker. I haven't tried that yet.

I felt the breaker in my panel after it tripped and it was warm.

Any idea? I am using a 20A breaker (dont know the wire size -- assume its code compliant since its brand new) with a 6-20 adapter. I have a few other "larger" circuits in my panel (30As) and those have been working fine.

Getting an electrician to look at the whole system is a definite need. In the meantime, you could do a little investigation to help provide information to the electrician and help you understand your charging situation.
Things to look at:
1. Is your 6-20 receptacle a stand alone, dedicated circuit? When it trips the breaker, does anything else lose power?
2. What amps is your car set to while charging using the 6-20 receptacle? Should be 16 amps or less.
3. If this a new home, could charging be affected by the circuit being protected by GFCI?

I would want to understand the garage electrical circuits and any interaction between your side and the owner’s.

 

[Gauss Guzzler]

It's common for breakers to trip from overheating due to inadequately tightened terminals but it usually takes many minutes or even hours to heat up to overtemp. And this usually only happens on high current (>30A) breakers.

For your breaker to trip so quickly seems to suggest it is going over-current or GFCI. Does the breaker have a GFCI "test" button on it? If so, I'd expect that the panel/circuit grounding is poor or the breaker is out of spec. Your subpanel arrangement sounds sketchy so it could be something as simple as an inappropriately bonded neutral bus.

If it's not GFCI then overcurrent is the most likely culprit. 6-20 circuits are extremely rare and almost never installed as such - they are usually converted from an existing 120V circuit. So there's a high probability that something else may be on that circuit, it may even be a 120V appliance that is tolerant of 240V.

For further diagnosis you can also watch the voltage and current display inside the car at the beginning of the charge for insight.