EV Charging Circuit - Breaker Hot

hifiandy said:

I installed a new 50 amp circuit to charge my EV.

Some specifics on the circuit - 50 amp breaker, 6-2 ga copper wire (UFB because in the future I may place the charger outside and wanted flexibility), NEMA 6-50 plug, Grizzl-e charger at 40 amps.

My question is on the breaker itself. I have a GE load center and installed a THQP250 breaker which is the thin line 50 amp breaker and verified torque to the 35 in.lbs. specified on the breaker. My other breakers are also the thin line series and space is tight in my panel. When charging, my breaker is at 125F temperature, which is about 45F over the rest of the panel. While I believe this is per UL, it still seems higher than it should be. I think the obvious first step is to replace the breaker with an equivalent, which I'm planning to do, but my real question is there a heavy duty breaker that should be used in this application?

Appreciate the input.

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Megawatt said:

I’m surprised that your breaker hasn’t Tripped yet. You need to put an amp meter to see exactly what kind of load you are actually pulling. You are not allowed to use over 80% of the breaker size. Good luck

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hifiandy said:

I put a clamp meter on the circuit and it is pulling 41 amps, which was expected as the charger is rated at 40 amps and there's no indication it is not functioning properly. So, the two questions still remain.

1. Is the breaker temp of 125F reason to be concerned (+45F over nominal)?
2. Should I replace the breaker with a thin-line equivalent or possibly switch to the full-size equivalent which would take a fair amount of work to move other breakers and make space?

Thanks

Click to expand...

hifiandy said:

I put a clamp meter on the circuit and it is pulling 41 amps, which was expected as the charger is rated at 40 amps and there's no indication it is not functioning properly. So, the two questions still remain.

1. Is the breaker temp of 125F reason to be concerned (+45F over nominal)?
2. Should I replace the breaker with a thin-line equivalent or possibly switch to the full-size equivalent which would take a fair amount of work to move other breakers and make space?

Thanks

Click to expand...

hifiandy said:

I put a clamp meter on the circuit and it is pulling 41 amps, which was expected as the charger is rated at 40 amps and there's no indication it is not functioning properly. So, the two questions still remain.

1. Is the breaker temp of 125F reason to be concerned (+45F over nominal)?
2. Should I replace the breaker with a thin-line equivalent or possibly switch to the full-size equivalent which would take a fair amount of work to move other breakers and make space?

Thanks

Click to expand...

hifiandy said:

I moved some breakers to make room for a full-size 50 amp breaker for my EV charger circuit. While a bit of work, the new full-size breaker is at 107F (still a nominal temp in the panel of 80F) after fully warmed up and has been charging over an hour. I am much happier with this temperature, it feels warm to the touch but not hot as previously. EV chargers are a unique load case because they can pull full amperage (80% of circuit per code) for literally 8 hours straight. I did not increase the breaker size to 60 amp because both the wiring and receptacle are rated for 50 amps and increasing the breaker to 60 amp would be a code violation. While working on it I did take some pictures of both the slim-line and full-size breakers to see the contact area and the conclusion I reached is that slim-line breakers are not preferable for this type of application, due to the limited contact area with the bus bar. Pictures attached for reference.

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Megawatt said:

Them slim line breakers contacts I’m not sure that they can carry current like the regular size. Just keep up with your new breaker on the heating up. It should not be warm to the touch. It needs to be a bigger service

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