40A Breakers Get Hot When Charging

[Bikeman]

Update: The Siemans breaker was installed earlier last week. The fit was more "firm" than the GE. We're watching it closely. At 31A/235v it still gets warm on a 1.5 hour charge, but not as hot as the GE breaker. We noticed the 8g wires to the outlet a foot or more from the breaker also get warm after a while. This worries me but that might be somewhat normal?

That said, the original breaker had moments when it was only slightly warm but on other charge cycles was quite hot. The behavior was random. It might still be. More than likely will be replacing the outlet and the box around it next, Only dedicated electrical supply outlets carry Hubble or Bryant 14-50's. Forget Home Depot, Lowes or Mennards for those. Only $10 crap (which weigh basically nothing) are available in the big box stores.

 

[retbesla]

Update: The Siemans breaker was installed earlier last week. The fit was more "firm" than the GE. We're watching it closely. At 31A/235v it still gets warm on a 1.5 hour charge, but not as hot as the GE breaker. We noticed the 8g wires to the outlet a foot or more from the breaker also get warm after a while. This worries me but that might be somewhat normal?

That said, the original breaker had moments when it was only slightly warm but on other charge cycles was quite hot. The behavior was random. It might still be. More than likely will be replacing the outlet and the box around it next, Only dedicated electrical supply outlets carry Hubble or Bryant 14-50's. Forget Home Depot, Lowes or Mennards for those. Only $10 crap (which weigh basically nothing) are available in the big box stores.

Is there a way to test the temperature? There are many of us experiencing such "hot" issues, and you know it's challenging to figure out how hot is too hot.

I'll post my new results later...



Btw, besides Siemans' breaker, any other recommended brands?

 

[jcanoe]

Is there a way to test the temperature? There are many of us experiencing such "hot" issues, and you know it's challenging to figure out how hot is too hot.

I'll post my new results later...



Btw, besides Siemans' breaker, any other recommended brands?

You use a hand held infrared thermometer (cost: under ~$20).

 

[retbesla]

1 50A Breaker	2 LEFT end of 7' conduit (3/4") with #6 AWG.	3 RIGHT end of 7' conduit (3/4") with #6 AWG.	4 NEMA 14-50 Plug into - Old: Leviton New: Hubbell	5 Gang Box	6 LEFT end of 2' Input Cable to EVSE L2.	7 RIGHT end of 2' Input Cable to EVSE L2.	8 JuiceBox 40, EVSE L2.	9 LEFT end of 25" Extension Cable.	Notes
			120-140°F Leviton	120-140°F 2-1/8" box					July - 206V, 40A, 74°F
94°F	81°F	83°F	92°F Hubbell	87°F 4" box	91°F	93°F	94°F	90°F	Aug - 211V, 32A, 80°F, 89% humidity, charging 3-hours.
102°F	84°F	87°F	97°F Hubbell	93°F 4" box	94°F	97°F	99°F	96°F	Aug - 206V, 36A, 81°F, 68% humidity, charging 3-hours.
108°F	87°F	91°F	103°F Hubbell	99°F 4" box	103°F	103°F	102°F	101°F	Aug - 204V, 40A, 82°F, 64% humidity, charging 3-hours.

1. I had no temperature heat gun or infrared thermometer earlier, so I couldn't gauged the temperature. I know it's "hotter" than the bottom of my WiFi router, and my Dyson vacuum wire. And, it's something that I could touch, but didn't want to touch it any further.
2. While waiting for new Hubbell installation, I ordered Etekcity Infrared Thermometer 1080 Heat Temperature Temp Gun, and used it for testing.
3. Not sure if I should worry the temperature with 50A Breaker. Some said it's okay up to 140°F. Some said it's okay as long as the temperature difference between the breaker and surrounding environment is less than 50°F. Or should I replace the breaker to something better? Any brands? Thanks.

 

[davewill]

I can't say I find any of those temperatures unusual. My general rule of thumb is that nothing should get so hot you can't keep a hand on it. Of course, you don't want to go around touching live circuits to test, but those temperatures are well within that rule of thumb.

 

[retbesla]

1 50A Breaker	2 LEFT end of 7' conduit (3/4") with #6 AWG.	3 RIGHT end of 7' conduit (3/4") with #6 AWG.	4 NEMA 14-50 Plug into - Old: Leviton New: Hubbell	5 Gang Box	6 LEFT end of 2' Input Cable to EVSE L2.	7 RIGHT end of 2' Input Cable to EVSE L2.	8 JuiceBox 40, EVSE L2.	9 LEFT end of 25" Extension Cable.	Notes
			120-140°F Leviton	120-140°F 2-1/8" box					July - 206V, 40A, 74°F
94°F	81°F	83°F	92°F Hubbell	87°F 4" box	91°F	93°F	94°F	90°F	Aug - 211V, 32A, 80°F, 89% humidity, charging 3-hours.
102°F	84°F	87°F	97°F Hubbell	93°F 4" box	94°F	97°F	99°F	96°F	Aug - 206V, 36A, 81°F, 68% humidity, charging 3-hours.
108°F	87°F	91°F	103°F Hubbell	99°F 4" box	103°F	103°F	102°F	101°F	Aug - 204V, 40A, 82°F, 64% humidity, charging 3-hours.

1. I had no temperature heat gun or infrared thermometer earlier, so I couldn't gauged the temperature. I know it's "hotter" than the bottom of my WiFi router, and my Dyson vacuum wire. And, it's something that I could touch, but didn't want to touch it any further.
2. While waiting for new Hubbell installation, I ordered Etekcity Infrared Thermometer 1080 Heat Temperature Temp Gun, and used it for testing.
3. Not sure if I should worry the temperature with 50A Breaker. Some said it's okay up to 140°F. Some said it's okay as long as the temperature difference between the breaker and surrounding environment is less than 50°F. Or should I replace the breaker to something better? Any brands? Thanks.

 

[retbesla]

I can't say I find any of those temperatures unusual. My general rule of thumb is that nothing should get so hot you can't keep a hand on it. Of course, you don't want to go around touching live circuits to test, but those temperatures are well within that rule of thumb.

Thanks. Just hope this new setup can give me a peace of mind.

My previous Leviton's X "hole" (for the hot line conductor) had the black burnout mark already. I believe it will start to melt sooner or later. It can't even "hold" any temperature during such high-efficient high-current EV charge for a long time. And, in those online shopping sites, we can still see tons of positive reviews about buying Leviton for EV charging. Unbelievable!!!

Anyway, since I'm not driving a lot, I'm going to stay with 32-36A. Unless I'm rush to get my car charged the quickest.

 

[Surfer of Life]

Household electrical rated for 50 Amps at 240 Volts AC should work flawlessly at 50 Amps and 240 Volts AC, IMHO. Installation shouldn’t be rocket science, and simple rated wire connectors should not fail.

But apparently it’s just not necessarily so. I bought a simple generic outlet fixture at a big- box store to home-charge my model X Tesla (35 Amps max at 240 VAC) using the heaviest gauge copper wire it was rated for just to be safe. Imagine my surprise when simply tightening the terminal screws against the wires deformed the rickety terminals and destroyed the terminals one after the other.

A mandatory watch for all new Tesla owners IMHO, Sandy Munro discusses this issue:

TL;DW? Buy a Hubble brand outlet, but this video shows examples like a properly installed junction box and breakers that melted and burned while running at typical EV charging capacity.

 

[Surfer of Life]

A mandatory watch for all new Tesla owners IMHO, Sandy Munro discusses this issue in his video.

Household electrical rated for 50 Amps at 240 Volts AC should work flawlessly at 50 Amps and 240 Volts AC, IMHO. Installation shouldn’t be rocket science, and simple rated wire connectors should not fail.

But apparently it’s just not necessarily so. I bought a simple generic outlet fixture at a big- box store to home-charge my model X Tesla (35 Amps max at 240 VAC) using the heaviest gauge copper wire it was rated for just to be safe. Imagine my surprise when simply tightening the terminal screws against the wires deformed the rickety terminals and destroyed the terminals one after the other.

TL;DW? Buy a Hubble brand outlet, but this video shows examples like a properly installed junction box and breakers that melted and burned while running at typical EV charging capacity.

 

[henderrj]

Household electrical rated for 50 Amps at 240 Volts AC should work flawlessly at 50 Amps and 240 Volts AC, IMHO. Installation shouldn’t be rocket science, and simple rated wire connectors should not fail.

But apparently it’s just not necessarily so. I bought a simple generic outlet fixture at a big- box store to home-charge my model X Tesla (35 Amps max at 240 VAC) using the heaviest gauge copper wire it was rated for just to be safe. Imagine my surprise when simply tightening the terminal screws against the wires deformed the rickety terminals and destroyed the terminals one after the other.

A mandatory watch for all new Tesla owners IMHO, Sandy Munro discusses this issue:

TL;DW? Buy a Hubble brand outlet, but this video shows examples like a properly installed junction box and breakers that melted and burned while running at typical EV charging capacity.

Although you are correct that cheap junk is still cheap junk, and breaks and melts and everything else bad, nevertheless the rule is 80% for continuous power. 100% for peak. Since charging EVs are a very definitely continuous load for hours on end, even 80% maybe pushing that for which the standard was originally designed.

 

[navguy12]

Although you are correct that cheap junk is still cheap junk, and breaks and melts and everything else bad, nevertheless the rule is 80% for continuous power. 100% for peak. Since charging EVs are a very definitely continuous load for hours on end, even 80% maybe pushing that for which the standard was originally designed.

Maybe overkill, but I never draw more than 20 amps from a 30 amp circuit when charging an EV under my control.

 

[Rocket_man]

When I charge over night I set the charge rate lower to pull less current, such that it will be charged just before I wake up the next day. In other words, while I could charge at 32 amps I normally charge around 26 amps. I still get to 100% before I drive off in the morning, but pull less current, create less heat. This time of year my garage easily gets over 100 degrees during the day, still warm overnight. So I'm pulling about 50% of the current capacity of the 50 amp circuit. Still 26 amps for 6 hours is a lot of power. No other household system even comes close.

 

[W7PP]

I find it funny that some of you think "warm to the touch" is a way to tell if it's hot or not. I live in Arizona, my breaker box is outside! When the outside air is 115, the box (and the house) fells "warm to the touch". I've seen my screen door frame at 159f on a sunny day. They wrap pot holder around door handles at restaurants... Google is your friend... Find the spec's to the breaker to find it's operating range. If it's in that range, things are ok, if it's over, find the weakest point and fix it. As far as wire size... 6ga is WAY better at 40-50 amps than 8ga. Look to see if your wire is rated at 105c, not 90c. or lower! Good luck with your "warm to the touch" problems!

 

[retbesla]

I find it funny that some of you think "warm to the touch" is a way to tell if it's hot or not. I live in Arizona, my breaker box is outside! When the outside air is 115, the box (and the house) fells "warm to the touch". I've seen my screen door frame at 159f on a sunny day. They wrap pot holder around door handles at restaurants... Google is your friend... Find the spec's to the breaker to find it's operating range. If it's in that range, things are ok, if it's over, find the weakest point and fix it. As far as wire size... 6ga is WAY better at 40-50 amps than 8ga. Look to see if your wire is rated at 105c, not 90c. or lower! Good luck with your "warm to the touch" problems!

IMHO. Food is hot. Coffee is hot. I think everyone agrees what you said. People feel "hot" differently, and people hear sound/pitching noise differently. And, environments make things differently. But I won't call it's funny. And not everyone has the way to gauge the true temperature, or, for example, frequency/loudness of noise. So, this happens. Should I measure the true temperature when I complain to the barista that my coffee is too hot?

Figuring out "how hot is too hot" is always challenging. We need a tool. For those don't have the heat gun or infrared thermometer, sharing the environmental temperature and more factors will help others know what's going on. (For noise issue, video/audio clips can be helpful.) Everyone is learning how-to.

 

[davewill]

I find it funny that some of you think "warm to the touch" is a way to tell if it's hot or not. I live in Arizona, my breaker box is outside! When the outside air is 115, the box (and the house) fells "warm to the touch". I've seen my screen door frame at 159f on a sunny day. They wrap pot holder around door handles at restaurants... Google is your friend... Find the spec's to the breaker to find it's operating range. If it's in that range, things are ok, if it's over, find the weakest point and fix it. As far as wire size... 6ga is WAY better at 40-50 amps than 8ga. Look to see if your wire is rated at 105c, not 90c. or lower! Good luck with your "warm to the touch" problems!

If you're referring to my post above, I did NOT say "warm to the touch". I said "so hot you can't keep your hand on it", and I said it was a rule of thumb, meaning something to use when you don't have the right tool. If I found something to be that hot, then I'd be looking to actually measure the temperature, as you suggest.

 

[leoita]

At 48A, the breaker and the charging cable is warm, but not hot.

 

[flixden]

I checked today. I am charging at 36A, and nothing gets hot. It's difficult to actually feel much if any warmth. Checked the 14-50 plug, charge cable, breaker.