EV charger breaker overheating

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SR59

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Florida
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Hello,

I am having problems with the EV charger breaker overheating and tripping. Below are the details.

Eaton CH panel
50 amp GFCI double pole breaker
6 gauge wire
Heavy duty disconnect switch
Hubbel/Bryant heavy duty 14-50 receptacle
Emporia EV charger
40 amp charge rate
Torqued to specs (checked multiple times after usage)

The EV charger works for around 60-90 minutes and then the breaker trips. I checked the temperature on the breaker with a thermal camera after about 60-90 minutes of usage. 140-147 degrees! It is very hot to touch. The breaker will not turn back on until it has cooled down (30+ mins). Then it runs again for the same amount of time and the same result.

The Emporia EV charger plug temperature was around 137 degrees.

Not sure what to do. Everything is setup correctly.

Thanks!
 
Did you measure the actual current draw? A defective EVSE can tell the charger to draw too much, although that’s a rare fault.

How’s the breaker to bus connection look?
 
High breaker temperature is a symptom of the breaker being overloaded or of a loose connection.

My guess would be that the breaker to panel bus stab connection is damaged, but the problem could also be internal to the breaker.

(Or what @retirede said!)
 
If I were troubleshooting this (full disclosure - not an electrician!!)...

Without touching anything yet, with the car charging I'd measure the FOP (fall of potential) across each leg of the 2 pole 50A breaker. The leads of you DVM should be measuring the voltage drop between the "Load" screw (where your #6 wire lands) and the bus for that leg. I would think at 40 amps you'd see a few tenths (max). See what you measure, and if one leg is significantly more than the other.

After that, then see what the bus stabs look like.

Can you move the breaker to another open spot and repeat the FOP test? Even if that's not where the breaker will live forever.

In a pinch, while getting to the bottom of this problem, if the Emporia supports variable amperage settings, you can drop the EVSE to 24A or 32A. The breaker heating should go down (the "square" in I² R is your friend here). Yes, you're charge times are longer, but when the breaker trips, you ain't charging at all.
 
Did you measure the actual current draw? A defective EVSE can tell the charger to draw too much, although that’s a rare fault.

How’s the breaker to bus connection look?
Yes. I used a clamp meter. Each leg was drawing about the same amps....right around 40 amps.

There are no burn marks or discoloration in the breaker to bus connection. I had the panel cover off and examined it for a long time. No arcing or any other issues. It was a tight fit to the bus.
 
High breaker temperature is a symptom of the breaker being overloaded or of a loose connection.

My guess would be that the breaker to panel bus stab connection is damaged, but the problem could also be internal to the breaker.

(Or what @retirede said!)
It is a 50 amp breaker. Current draw is 40 amps. I checked with a clamp meter.

I checked every connection in the mix multiple times. Everything is torqued properly.

There are no burn marks or discoloration in the breaker to bus connection. I had the panel cover off and examined it for a long time. No arcing or any other issues. It was a tight fit to the bus.
 
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If I were troubleshooting this (full disclosure - not an electrician!!)...

Without touching anything yet, with the car charging I'd measure the FOP (fall of potential) across each leg of the 2 pole 50A breaker. The leads of you DVM should be measuring the voltage drop between the "Load" screw (where your #6 wire lands) and the bus for that leg. I would think at 40 amps you'd see a few tenths (max). See what you measure, and if one leg is significantly more than the other.

After that, then see what the bus stabs look like.

Can you move the breaker to another open spot and repeat the FOP test? Even if that's not where the breaker will live forever.

In a pinch, while getting to the bottom of this problem, if the Emporia supports variable amperage settings, you can drop the EVSE to 24A or 32A. The breaker heating should go down (the "square" in I² R is your friend here). Yes, you're charge times are longer, but when the breaker trips, you ain't charging at all.
There are no burn marks or discoloration in the breaker to bus connection. I had the panel cover off and examined it for a long time. No arcing or any other issues. It was a tight fit to the bus.

I already tried moving it to a different spot. Same issue.

Yep. I have to tried charging at a lower amp setting. It works but just takes a longer time.

I used a clamp meter. Each leg was drawing about the same amps....right around 40 amps.

The voltage at the 14-50 receptacle is the same on both legs.
 
Is this a new breaker or a aged one? Have you replaced the breaker itself?
Breaker is new. Manufacturing date on the breaker is March 2021.

No. I have not replaced the breaker yet. I want to make sure that the breaker is the reason for the issues before replacing.
 
Breaker is new. Manufacturing date on the breaker is March 2021.

No. I have not replaced the breaker yet. I want to make sure that the breaker is the reason for the issues before replacing.
Does this breaker have an LED indicating what kind of trip? GFCI trip vs over current trip?
 
Does this breaker have an LED indicating what kind of trip? GFCI trip vs over current trip?
No, it does not.

It definitely is not overcurrent. The car and EV charger apps both show that only 40 amps are being drawn.

Sometimes, the breaker trips even when the EV charger is not charging the car. This is expected since the EV charger has a built in GFCI that causes nuisance trips.

But most of the times, it trips when the breaker is very hot. I can't even turn the breaker back on. After it tripped due to heat, I removed the EV charger load to make sure it was not causing a nuisance trip. The breaker would not turn back on even with the EV charger load removed. I have to wait until it cools down before it turns back on.
 
The plug of the EV charger that goes into the 14-50 receptacle is also hot. 137 degrees.

Would a bad breaker cause the plug to be hot?

A bad breaker would not heat up the plug.

A warm plug is not a problem. A hot plug might indicate a problem.

What is your profession? I've been answering questions presuming you are an electrician chasing an installation problem. The issue is that we don't know what you don't know and what you don't know to ask. If you are not an electrician my advice is to hire one.

Jon
 
A bad breaker would not heat up the plug.

A warm plug is not a problem. A hot plug might indicate a problem.

What is your profession? I've been answering questions presuming you are an electrician chasing an installation problem. The issue is that we don't know what you don't know and what you don't know to ask. If you are not an electrician my advice is to hire one.

Jon
I am not an electrician. I am in the IT field.
 
I want to make sure that the breaker is the reason for the issues before replacing.

Would a bad breaker cause the plug to be hot?
Nope, current is the cause, period. But a 50a breaker should be able to carry 40a continuously.
 
When Tesla was providing 100 amp rated wall chargers to their customers , I would get a pretty fair amount of service calls to repair the damages to the circuit breakers and busbars feeding the charger devices , ( installed by other companies incidentally). Now Tesla sells only lower value max 48 amps chargers, the problems I get calls to come repair are not often any longer. Tesla know the answer to this issue but perhaps that is a tightly held company secret?
 
No, it does not.

It definitely is not overcurrent. The car and EV charger apps both show that only 40 amps are being drawn.

Sometimes, the breaker trips even when the EV charger is not charging the car. This is expected since the EV charger has a built in GFCI that causes nuisance trips.

But most of the times, it trips when the breaker is very hot. I can't even turn the breaker back on. After it tripped due to heat, I removed the EV charger load to make sure it was not causing a nuisance trip. The breaker would not turn back on even with the EV charger load removed. I have to wait until it cools down before it turns back on.
How does the internal GFCI cause the breaker to trip?
 
How does the internal GFCI cause the breaker to trip?
The Emporia EV charger has built in GFCI. It does a self-test every so often. Emporia tech support confirmed that when the EV charger performs a self-test, it will trip the GFCI breaker since the breaker tolerance is only 5mA.
 
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