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HWPC getting hot, breaker and conduit too.

Hey All,

I have a new HWPC running on a 60 amp breaker, 6 guage THHN wire. Today i was in the garage and grabbed the conduit and noticed it was really warm. I decided to go check on the breaker and it was very hot too the touch, measured the temp with a cheap IR thermometer at 142F. It's only getting hot when my M3 LR is pulling the full 48 amps. Does anyone elses HWPC/Conduit and Breaker get really hot when the car is charging at full speed?
 

N54TT

Active Member
Aug 14, 2018
1,039
872
NY
Hey All,

I have a new HWPC running on a 60 amp breaker, 6 guage THHN wire. Today i was in the garage and grabbed the conduit and noticed it was really warm. I decided to go check on the breaker and it was very hot too the touch, measured the temp with a cheap IR thermometer at 142F. It's only getting hot when my M3 LR is pulling the full 48 amps. Does anyone elses HWPC/Conduit and Breaker get really hot when the car is charging at full speed?

I would stop using it and call your electrician ASAP. I’ve felt my panel and breakers….they’ve never been more than warm to the touch.
 
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TBrownTX

Active Member
Dec 25, 2020
1,061
1,263
Dallas, TX
Hey All,

I have a new HWPC running on a 60 amp breaker, 6 guage THHN wire. Today i was in the garage and grabbed the conduit and noticed it was really warm. I decided to go check on the breaker and it was very hot too the touch, measured the temp with a cheap IR thermometer at 142F. It's only getting hot when my M3 LR is pulling the full 48 amps. Does anyone elses HWPC/Conduit and Breaker get really hot when the car is charging at full speed?

I'm also using the HPWC with a 60AMP breaker. I use 4 gauge NM-B inside the wall, versus 6 guage THHN in conduit. I believe the 6 guage THHN can handle more heat than my larger gauge NM-B. Regardless, my breaker only gets warm, like no warmer than the HPWC's charging cable where it plugs into the car. It's never gotten anywhere near was warm as you re describing, I'd cut the breaker and check the lugs for torque (or call the electrician to have it checked). Not normal at all IMHO.

Tim
 
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Next time I have a long charge at the house, I'll measure my ambient temp as well as both breakers and the conduit/connector wire temps.

I have a subpanel fed with a 100 amp breaker to the garage and a 60 amp circuit with THHN wire with metal flex conduit. I believe it's 6ga copper, but will check that as the electrician did all of that part. My breakers (both the 100 amp and the 60 amp) get roughly the same temperature and the metal flex conduit seems to be around the same temperature. Again, I'll get out the infrared thermometer and get some readings the next time I have a long charge (if anyone is interested in a comparison).
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,661
18,784
Riverside Co. CA
Hey All,

I have a new HWPC running on a 60 amp breaker, 6 guage THHN wire. Today i was in the garage and grabbed the conduit and noticed it was really warm. I decided to go check on the breaker and it was very hot too the touch, measured the temp with a cheap IR thermometer at 142F. It's only getting hot when my M3 LR is pulling the full 48 amps. Does anyone elses HWPC/Conduit and Breaker get really hot when the car is charging at full speed?

I would suggest getting the electrician that installed it to code back out there to investigate. If you are the one who installed it, you likely want to check to make sure you torqued everything down properly, and if so, get an electrician out there to investigate the install and verify everything is done properly, and to code.
 
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142F is only 61C. It might not be a problem, but it does seem unusual. What was the ambient air temperature?

I've checked my 6AWG NMB after three hours at 48 amps (not technically allowed, it was an experiment), and it was only warm, 88f if I recall correctly. But that was in a 65f basement.
Ambient airtemp in my garage was around 90F, pretty warm out here in socal right now.
 
Next time I have a long charge at the house, I'll measure my ambient temp as well as both breakers and the conduit/connector wire temps.

I have a subpanel fed with a 100 amp breaker to the garage and a 60 amp circuit with THHN wire with metal flex conduit. I believe it's 6ga copper, but will check that as the electrician did all of that part. My breakers (both the 100 amp and the 60 amp) get roughly the same temperature and the metal flex conduit seems to be around the same temperature. Again, I'll get out the infrared thermometer and get some readings the next time I have a long charge (if anyone is interested in a comparison).
Thanks alot!
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
11,974
15,508
San Diego
Hey All,

I have a new HWPC running on a 60 amp breaker, 6 guage THHN wire. Today i was in the garage and grabbed the conduit and noticed it was really warm. I decided to go check on the breaker and it was very hot too the touch, measured the temp with a cheap IR thermometer at 142F. It's only getting hot when my M3 LR is pulling the full 48 amps. Does anyone elses HWPC/Conduit and Breaker get really hot when the car is charging at full speed?

What's the difference in the voltage reported in the car, when the car is drawing 0A, vs. when it is drawing 48A? With that information you can calculate the power dissipation in your cable run, from your breaker to the vehicle. A good first step, if you are worried about things, but doesn't necessarily tell you whether there is a problem or not, since a bunch of the loss could be in one location, which is what can cause fires. A lot of voltage drop may be bad (7-10V is pretty typical but heavily depends on the length of the run), but a smaller observed voltage drop is not sufficient to guarantee that there is no problem.

Also, how long is the run?

50 degrees above ambient seems a bit higher than I would expect, but I haven't calculated, to figure out what one should expect (it's a much harder problem to calculate this, as it very much depends on your installation). So I have no idea whether there is anything wrong.

48A is a lot of current through 6AWG, of course. I would expect that to get warm, for sure. Just not sure how warm.
 

N54TT

Active Member
Aug 14, 2018
1,039
872
NY
I’m on a 50amp breaker, current temp in my garage is 90deg, I have my central air running full blast and car charging. I don’t have an IR thermometer but none of the breakers are more than just warm. Checking to see if there’s a voltage drop will help clue you in if there’s problem. But if it’s too hot to touch, I highly doubt that’s normal. I would get your electrician to just confirm everything is okay if anything. Last thing you want is to have a fire.
 

ATPMSD

Active Member
Mar 12, 2021
1,345
1,233
Atlanta, GA
make sure you torqued everything down properly

Definitely worth checking the wires on the breaker and wall connector. When ambient temperature goes up fitting often loosen up. An easy thing to do if you are comfortable opening up the panel and wall connector. BUT don’t do it if an electrician did the install, he should fix it for free and you do not want to give him an out by you messing with it.
 
Haven't had a chance to really drive a long distance over the past couple days, but am down to 76%. I'll drive some more tomorrow and get a charge session going and measure some temperatures. Had anticipated making a long drive to bring it down to 20% or so today, but a co-worker decided to drive his vehicle... Anyway, I'm still planning to get a temperature profile of my setup. Just taking a little longer than I anticipated.
 
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Here's a 1 hour and 15 minute charge profile with temperatures along the line. HTH

1625857489577.png
 

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