I have an EVSE from OpenEVSE | Home that I've had for over 3 years charging my Cmax Energi and 500e. I have it plugged into a Nema 6-20 outlet and it has worked fine during that time. Last week I got my 3 and I am regularly tripping the breaker. I started with both the EVSE and car set for a max 20A. I then dropped them down to 16A, and then 12A. It will still trip often. I need to be standing there when I start charging to be sure that it will work OK. I got it to work last night after 3-4 tries and charged overnight. This morning when I went out to leave for work I woke the car up to unplug it and as soon as it woke up the breaker tripped again. Any ideas as to what could be happening?
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Breaker tripping
- Thread starter Effopec
- Start date
I would try replacing the breaker first. They can go bad, believe it or not.
BTW - a 20a breaker should have max allowable current of 16a for an EVSE due to the 80% rule for continuous loads.
BTW - a 20a breaker should have max allowable current of 16a for an EVSE due to the 80% rule for continuous loads.
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For $35.00 you can bypass EVSE and get a NEMA 6-20 adapter in order to isolate the problem:
Model S/X/3 Gen 2 NEMA Adapters
If it still fails and you have the skill, check to make sure all wiring connections are torqued tightly. Loose wires can trip circuit breakers. Also, consider replacing your circuit breaker if old. Certain brands such as Pushmatic fail after 40 years or so. I had a kitchen recently remodeled and they replaced every circuit breaker even those less than ten years because their experience with failures.
Model S/X/3 Gen 2 NEMA Adapters
If it still fails and you have the skill, check to make sure all wiring connections are torqued tightly. Loose wires can trip circuit breakers. Also, consider replacing your circuit breaker if old. Certain brands such as Pushmatic fail after 40 years or so. I had a kitchen recently remodeled and they replaced every circuit breaker even those less than ten years because their experience with failures.
I put in a brand new breaker from Home Depot and it failed after 2 weeks. They do have problems occasionally.
Especially if you have been running 20a through a 20a breaker. It should be limited to 16a.
eprosenx
Active Member
If you have an EVSE plugged into a 20a circuit then it should be configured to tell the car that plugs into it that the max current allowed to be drawn is 16a. If your Tesla was letting you draw more than that then the EVSE is sending the wrong signal to the car.
Now it is confusing why it was tripping even when you cranked the power down lower manually. It is true that breakers can be faulty or go bad over time (especially on a circuit that has seen years of repeated high current draw and especially after being over stressed like by drawing 20a on a 20a circuit) but I would expect it to take a little time to blow after the breaker heated up. I would not expect that once you got it to start charging it would last all night fine... I don’t suppose it is a GFCI breaker is it?
Regardless, as others have mentioned, a loose wire into the breaker can cause heat buildup in the wire which radiates into the breaker heating it up and causing it to trip. If you can do it safely, tightening the screw terminals (with the power turned off of course since the screws are energized) may help. Though I would without question just replace the breaker since they are cheap and pretty inexpensive to swap.
I have been told (and I believe it) that breakers are only rated for a handful of trips. After they have blown several times they can be damaged internally and they may not be calibrated accurately. I wonder if your previous cars never could draw enough power (beyond 16a) to stress that circuit (even though the EVSE was sending the wrong signal) and so that is why it worked. But then you got the Tesla which can draw more than 16a and so since the EVSE told it that it was allowed to, it did. That may have damaged the breaker and so now even manually cranking down the amps is not working.
So my guess is replacing the breaker and settting the EVSE correctly to limit current to 16a may fix the issue.
Breakers are thermal devices. If the wire is not torqued properly on the breaker, that junction can generate heat and cause the breaker to trip. So, check the torque of the screw fixing the wire to the breaker first. If it seems OK, ie. you cannot tighten it more than 1/8 turn, then replace the breaker.
The prior suggestions about using the Tesla NEMA 6-20 adapter with the provided Tesla Mobile Connector and observing the 80% rule (20A circuit should only allow 16A charging) are good too.
The prior suggestions about using the Tesla NEMA 6-20 adapter with the provided Tesla Mobile Connector and observing the 80% rule (20A circuit should only allow 16A charging) are good too.
If you have an older GFCI breaker, that is likely the problem. The cars testing of the ground is tripping the breaker.
I'm not sure the rules, I think you are required to have GFCI for a 20a outlet. You can get around that by having a hardwired EVSE with ground fault built in.
You familiar enough with electricity to swap the breaker? I'd put in the cheap one and see if it works. Then go from there.
...or keep the regular breaker and just replace the outlet with a typical 20A GFCI outlet. Way cheaper anyway.
I have never seen a NEMA 6-20 (240V) GFCI outlet. A quick search at the Homedepot web site didn't reveal one either.
davewill
Active Member
I think the combination of a new breaker and setting the OpenEVSE properly to 16a should solve your problem. The setting in the OpenEVSE menu is for the actual current draw, NOT for the circuit size. The Fiat has a 6.6kW charger, so you've been pulling 20a through that breaker for an extended period. My guess is that either the Model 3 is tripping the GFCI because it does the ground check differently, or drawing 20a for so long damaged the breaker.
eprosenx
Active Member
Ah yes! This explains the behavior. It is almost certainly being tripped by the GFCI function of the breaker (rather than the thermal or magnetic trip components which are for overload and short circuit conditions respectively). We have seen Tesla's (generally with the UMC - interesting that your OpenEVSE is also experiencing this when it did not with other EV's) causing nuisance trips like this. I think though generally replacing the GFCI unit (in this case the breaker) with a new modern one has resolved the issue for most folks.
Question: Where is the receptacle? Is it outside in a potentially wet location, or is it inside in the garage in a dry location?
From a 2017 NEC code standpoint in article 625 it says receptacles for EV have to be GFCI regardless, though it kind of chaps me since the EVSE also has GFCI built in. I personally think it is not unreasonable to have a non-GFCI receptacle for EV's as long as it is in a dry location. The EVSE plugged into that receptacle will have its own GFCI function within a 12" distance from the receptacle. I might be tempted to swap that breaker with a non GFCI one if it was in a fully dry location, however, I can't recommend that as it is against code and you most certainly would not want to do that if it was tripping due to an actual real ground fault. You would just be bypassing that safety feature which was working.
Since we have identified that the issue is likely GFCI related and that something is already wrong with your existing EVSE, I would definitely try it with the Tesla UMC with the right adapter (though it will take a few day to get that probably).
I hate how expensive GFCI breakers are. $112 seems unreasonable. This is why the State of Oregon has whacked nearly all the new GFCI requirements in 2017 NEC. They accidentally missed the one that snuck into article 625 for EV charging ports. The committee did not get a chance to review that one since it was a last minute emergency change to insert it to the 2017 code.
Yeah, good point. Brain fart, thinking of 5-20, which is clearly wrong...
To be more precise, I think it is a TIA. It is the same one that allowed charging on NEMA outlets other than 5-15 and 5-20, so it is pretty important.
Picked up a new GFCI breaker at Home Depot (a bargain for $93 there) & installed it last night. Seems to have worked OK, at least for the first charge. Hopefully it continues to work OK. Have both the EVSE and car set for 16A max.
eprosenx
Active Member
Hah yes! I actually have read it. You are correct of course! (do you work in the industry?) It was a needed modification, but I wish they had not included the GFCI requirement for *all* installations. It would have been nice if it was only required in wet locations.
I'd have replaced the GFCI with a regular breaker and wired the EVSE directly, eliminating the outlet. But then I'm one of those tightwad Tesla owners...
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