Is my circuit breaker old/faulty?

[Gimmethecash]

I had an electrician install ~55 feet of 6/3 from an existing (unused) 50 amp circuit breaker in my main panel through (unused) conduit into a Tesla wall charger in my garage; I configured the charger for a 50 amp breaker to get 40 amps of charge rate. After ~5 minutes, the breaker tripped and was hot to the touch. No faults were detected.

I changed the wall charger config to expect a 40 amp breaker and I reset the circuit breaker in the panel. It will now charge at 32A (I’ve gone from 150-250 miles of charge a couple of times) but the breaker makes a light sizzling sound and gets pretty warm - after an hour or so, it’s ~180 degrees F on my laser thermometer.

I just sent a note to the electrician suggesting we replace the old breaker with a new 60 amp unit…does this sound like I’m on the right track? I’m getting 27mph charging, which plenty fast (though faster is better) but the sound and heat make me nervous. I’m not sure I want to come home late at night, plug in, and go to sleep unless this is normal.

I should add that the main (100A) breaker is also a bit warm and registering 140-150 degrees while charging and running the home AC simultaneously. I plan to not run AC and charge at the same time once I sort this out, assuming everything is running off a 100A breaker. Charging at night means I don’t need both of those on at the same time.

 

[Sophias_dad]

No, don't consider upping the breaker. Your 100amp service is already at its limit, putting another 10 amps of load on it won't make it any better, and you already said you don't need the speed.


As far as the potentially faulty breaker, the breaker itself may be( or probably is now) faulty, or its connection to the two bus bars that supply it may be weak. A bad connection is a source of heat and sometimes buzzing, and the heat will(or usually will) trip the breaker before your house burns down. Replacing the breaker should be done in any case, and your electrician should check if the breaker bar has been damaged due to arcing. 180f is 82c, and that's pretty hot. Wires in conduit are rated to 90C, for instance.


There are a few main panels and breakers that have been deemed defective over the years. Your electrician probably wouldn't have touched it if yours was one of those.


I had my main breaker replaced because I could hear sizzling occasionally under heavy load. I let the pro's take care of it because it was connected via an aluminum feeder wire and also don't have remove-the-meter technology.

 

[RayK]

I should add that the main (100A) breaker is also a bit warm and registering 140-150 degrees while charging and running the home AC simultaneously. I plan to not run AC and charge at the same time once I sort this out, assuming everything is running off a 100A breaker. Charging at night means I don’t need both of those on at the same time.

Several questions:

• How old is your house?
• Who is the manufacturer of the main electrical panel?
• Did your electrician do any load calculations prior to wiring your wall charger?

 

[Gimmethecash]

Thanks, guys. To answer RayK’s questions:

The house was built in 1937, I’m pretty sure it’s not the original panel, but possibly not by much.
It’s a GE panel.
At least one of the electricians I initially contacted did a load calculation (when we were talking about a 50A breaker) and said it checked out.

I have an appointment scheduled for tomorrow morning for them to look at it; I’ll be fine with whatever capacity breaker they replace it with (the 27mph I get at 32A draw is enough to charge 0-100 over night, even less would be fine most of the time), but they’ll also be able to look at the panel when they’re here - it’s the same electrician who did the initial charger install. I just need it to be safe and reliable, which is why I called them back out.

 

[Gauss Guzzler]

Breakers are only $10 so you might as well put a new one in even if the "sizzling" is merely due to loose terminals.

Your 100A panel will likely support a 60A breaker but 6/3 (Romex) has a 50A limit, only individual strands of 6 AWG in conduit can do 60A. Sounds like your main breaker is getting uncomfortably warm too, it's a bit more work to deal with the main but probably worth considering some effort there to make sure it's OK.

 

[Sophias_dad]

It isn't clear from the original post. Is that 6/3(NM-B/Romex) through conduit, or just three strands of conductor through conduit. The former is not allowed at all and the electrician should not have installed it.

 

[MN-MS100D]

If your electrician installed NM in an existing conduit from end to end, he is a complete idiot and needs to be dismissed from any consideration or payment.

 

[Gimmethecash]

It’s 3 individual insulated 6 gauge wires in the conduit.

 

[sunfarm]

I had an electrician install ~55 feet of 6/3 from an existing (unused) 50 amp circuit breaker in my main panel through (unused) conduit into a Tesla wall charger in my garage; I configured the charger for a 50 amp breaker to get 40 amps of charge rate. After ~5 minutes, the breaker tripped and was hot to the touch. No faults were detected.

I changed the wall charger config to expect a 40 amp breaker and I reset the circuit breaker in the panel. It will now charge at 32A (I’ve gone from 150-250 miles of charge a couple of times) but the breaker makes a light sizzling sound and gets pretty warm - after an hour or so, it’s ~180 degrees F on my laser thermometer.

I just sent a note to the electrician suggesting we replace the old breaker with a new 60 amp unit…does this sound like I’m on the right track? I’m getting 27mph charging, which plenty fast (though faster is better) but the sound and heat make me nervous. I’m not sure I want to come home late at night, plug in, and go to sleep unless this is normal.

I should add that the main (100A) breaker is also a bit warm and registering 140-150 degrees while charging and running the home AC simultaneously. I plan to not run AC and charge at the same time once I sort this out, assuming everything is running off a 100A breaker. Charging at night means I don’t need both of those on at the same time.

https://dccelectric.com/wp-content/uploads/2021/04/DCC_Specification-Sheet_DCC-10_LONG_V11-VF.pdf

That's what you need!! No overload panel, no warm breaker and enjoy super speed charging!!!

 

[jjrandorin]

https://dccelectric.com/wp-content/uploads/2021/04/DCC_Specification-Sheet_DCC-10_LONG_V11-VF.pdf

That's what you need!! No overload panel, no warm breaker and enjoy super speed charging!!!

This OP already has a circuit installed so that product is not needed at all in this case.

 

[Sophias_dad]

https://dccelectric.com/wp-content/uploads/2021/04/DCC_Specification-Sheet_DCC-10_LONG_V11-VF.pdf

That's what you need!! No overload panel, no warm breaker and enjoy super speed charging!!!

That's $1000, plus installation. I'd much rather spend the $1000 plus labor on upgrading my service/main panel.

The breaker that was warm was the 50 amp breaker feeding the OP's charger, so instead those wires would feed the DCC-10, and he'd STILL not solve the problem of the warm breaker.

 

[sunfarm]

This OP already has a circuit installed so that product is not needed at all in this case.

Can you explain to me why his circuit breaker heat? Did his electrician understood and calculated main panel overload even 50A circuit wasn't hook up yet?

 

[jjrandorin]

Can you explain to me why his circuit breaker heat? Did his electrician understood and calculated main panel overload even 50A circuit wasn't hook up yet?

No, thats for his electrician to explain when he or she comes back out to inspect it.

 

[sunfarm]

That's $1000, plus installation. I'd much rather spend the $1000 plus labor on upgrading my service/main panel.

The breaker that was warm was the 60 amp breaker feeding the OP's charger, so instead those wires would feed the DCC-10, and he'd STILL not solve the problem of the warm breaker.

Yes it' solve problem very well in my house. DCC cut power to EV charger if it's main panel overloaded more than 80% ( CEC). I did experiment turned on dryer, oven, hot water tank, hot tub, and A/C all the same time. DCC after 30 sec immediately disconnect it and I waited 15 min an start turn off power equipment- only left hot tub. 15 min later EV power was restored and charged car. Without DCC I need upgrade my Main Electrical Panel ( service which is cost between 5-10K)

 

[sunfarm]

No, thats for his electrician to explain when he or she comes back out to inspect it.

I can explain you why. Panel overload and this is very danger situation can create house fire.

 

[jjrandorin]

I can explain you why. Panel overload and this is very danger situation can create house fire.

The product you posted does not change or fix that, though.

 

[sunfarm]

The product you posted does not change or fix that, though.

I will be not argue with you no point explain it to you.

 

[Gimmethecash]

I (amateur) don’t think panel overload alone should cause an individual circuit breaker to get hotter than the others (including main). The working theory is that the existing breaker I’m using is old and/or going out (the noise backs that up), but the fact that the main breaker is only 100A and is getting warmer than I like (~130F) while charging and running AC in the middle of the day means I should back off a little bit on how fast I charge and also mitigate by charging after AC hours. And replace the old breaker.

It’s all speculation at this point though, and my appointment window starts in 20 minutes, so we shall see what the professional says.

 

[sunfarm]

I (amateur) don’t think panel overload alone should cause an individual circuit breaker to get hotter than the others (including main). The working theory is that the existing breaker I’m using is old and/or going out (the noise backs that up), but the fact that the main breaker is only 100A and is getting warmer than I like (~130F) while charging and running AC in the middle of the day means I should back off a little bit on how fast I charge and also mitigate by charging after AC hours. And replace the old breaker.

It’s all speculation at this point though, and my appointment window starts in 20 minutes, so we shall see what the professional says.

Will see, but any electrician a must calculate whole panel load and size of wire to hook up you breaker, before to do any job on you main panel. In my opinion it's a danger if main breaker heat 130F!!!! I hope you have good insurance.

 

[Sophias_dad]

Will see, but any electrician a must calculate whole panel load and size of wire to hook up you breaker, before to do any job on you main panel. In my opinion it's a danger if main breaker heat 130F!!!! I hope you have good insurance.

There are so many issues here...

130F is 54C, below the 60C minumum temperature rating of all the 120/240V wiring in every house in north america whether its in a wiring cabinet or not. Breakers themselves have terminals rated to accept at least 75C wires, and some will deal with 90C.

In theory, you could literally put a flame source inside the main panel, and it shouldn't catch the house on fire. (I don't have the specs right here, but I'm sure they are supposed to run out of fuel before the fire can escape the case). This assumes that there are no unfilled knockouts(either wires or breaker-spaces).

It is the job of the NEC to keep things safe even when there's a failure or two. With around 150 million homes around North America, and probably 3 billion circuit breakers in those homes, there WILL be unexpected failures, regardless of product design. I visited one home where the dishwasher was slowly pouring water(and detergenty-water, at that!) THROUGH a wiring sheath all the way down one row of breakers, and they were all slowly becoming intermittent.

It seems like the DCC-10 worked for you(and that's great!) but it doesn't mean it will fix everyone else's electrical challenges.