This thread reminds me. Good time to double check the torques and then check all the temps when I’m charging.
Temp Rise in plug, outlet, cords, etc.
- Thread starter Allistah
- Start date
I also noticed some electrical grease around some of the much thicker cables that go into the breakers. I'm guessing that this would also be a good precautionary practice to keep the area from getting dirty and exposing the contacts to debris and such. Not sure I'll do it, but it's probably a good idea based on what I see on other high current rated breakers in the panel.
That’s typically on the aluminum wires to prevent oxidation. I’m not sure if it helps copper connections.
Yeah, if the wire is sized according to NEC you will see a very noticeable temperature rise when it’s loaded for a while. Moving to the next size up wire helps, but not all that much. Wire isn’t really ‘good’ for a particular amount of current. The current it handles is generally limited by how hot the insulation can get before melting. And for short durations, it’s a lot. Most things in your house don’t take that much power for that long, so you wouldn’t notice it. With a 14-50, you probably can’t oversize the conductor that much anyways. You’re always limited to the weakest link in the chain. So if the breaker is only listed to accept up to #4, you can’t use anything larger than that. The receptacle and breaker should be marked with the conductor size range they are listed for. But as long as the wire wasn’t shredded during install, and the screws are tight on both ends, a bit warm is totally expected and normal. It should never be burning hot to the touch, but it is generally going to be fairly warm. A better outlet isn’t a bad idea, but the regular ones should be OK so long as you don’t unplug it a dozen times a day. They will get loose over time and slowly get hotter and hotter. I would assume Tesla would have put a temp sensor in the 14-50 plug on the wall connector to throttle charge power should it become too hot, but I’m not sure. If you see goop on wires into breakers, they’re probably aluminum. It’s required by code to use anti corrosion goop on aluminum conductors, and aluminum is typically used on larger capacity circuits since it’s much cheaper than copper. So it’s really just an aluminum wire thing and not a high current thing.
davewill
Active Member
Honestly, the temps you reported sound perfectly reasonable. I think your current install is probably just fine. That said, checking the torque and adding the ferrules is good and switching the oulet for the Hubble isn't a bad idea, either.
Hubbell outlet is out for delivery today so I'll have it within hours. Will be posting some pictures of it and comparing it to the cheap Leviton. Will make sure it's torqued properly and should be better now that I torqued the breaker. All this should add up to some improvements in heat generation. Will keep this thread posted on my progress.
Ok, I got the Hubbell HBL9450A outlet tonight. Took pictures of the contacts inside the two load-bearing slots. The Hubbell is on the top, the cheap Leviton is on the bottom. To begin with, the Leviton has about 20% less contact surface area - even if it was making good contact, the surface area is clearly about 20% less. Then look at that gap on the Leviton! Unbelievable - this is why it's worth it to get a Hubbell or another top brand. I don't know if the Bryant has the same internal quality as a Hubbell, but from the looks, it looks to be the same at a much reduced cost. I'm a bit skeptical of products like this, you get what you pay for so while it may look like the same quality as Hubbell, testing would only tell.
dmurphy
Woof.
There's a reason why, whenever I install data center equipment for my customers, we use either Hubbell or Mennekes connectors and receptacles.
I've never installed a PDU with a Leviton power connector, ever ...
Oh, I'm a full-on believer now. I trusted everyone was right before - just had faith that people knew what was good. But when you see it yourself and it's very clear the differences, it's a little shocking. I can't wait to see what the difference is in charging temp. Going to install it tomorrow. Will also be torquing each line to 75 inch lbs as stated by the docs that came with the outlet. Will post back again when I get some data.
These readings are 30m apart - charging at 40A after install Hubbell outlet, everything torqued to proper specs. All degrees are in F. Also checked the cable up I the attic and it was 84F (71 ambient) after 30m.
Wall = Wall next to outlet
Breaker = Surface of circuit breaker
Plug = The back of the plug that's plugged into the Hubbell outlet
Plate = The face plate on the 2 gang box next to the outlet
Item: 0m, 30m, 60m, 90m (All degrees in F)
------------------------------------
Wall: 74, 72 (-2), 76 (+4)
Breaker: 69, 96 (+27), 104 (+8)
Plug: 73, 92 (+19), 100 (+8)
Plate: 75, 81 (+6), 86 (+5)
Wall = Wall next to outlet
Breaker = Surface of circuit breaker
Plug = The back of the plug that's plugged into the Hubbell outlet
Plate = The face plate on the 2 gang box next to the outlet
Item: 0m, 30m, 60m, 90m (All degrees in F)
------------------------------------
Wall: 74, 72 (-2), 76 (+4)
Breaker: 69, 96 (+27), 104 (+8)
Plug: 73, 92 (+19), 100 (+8)
Plate: 75, 81 (+6), 86 (+5)
Last edited:
Eh, I wasn't able to get the 90 minute readings because I was on a call and my wife left with the car. lol
I will say that the cables and such are indeed cooler. The breaker and the plug that is plugged into the Hubbell are by far the two things that get the warmest.
Some takeaways from my experience:
Do not skimp on wire that's too thin.
Use the right sized circuit breaker
DO NOT - absolutely do not use a <$10 cheap 14-50 outlet. Not worth it. Get a Hubbell HBL9450A
Torque the breaker bolts to what is specified on the side of the breaker itself
Torque the outlet to its specs (Hubbell is 75 inch lbs)
Torque the line going into your Tesla Wall Connector to what it shows in the install manual 33 and 16 inch lbs)
Keep an eye on temps - don't always assume things are ok. Most meltdowns I've seen may have been caught earlier if they were watching the temps. Get an IR temp gun so you can see how hot things are - those are very affordable.
I'm planning on doing up to a 3 hour test at 40 amps at some point checking every 30 minutes but that will have to wait until next weekend.
I will say that the cables and such are indeed cooler. The breaker and the plug that is plugged into the Hubbell are by far the two things that get the warmest.
Some takeaways from my experience:
Do not skimp on wire that's too thin.
Use the right sized circuit breaker
DO NOT - absolutely do not use a <$10 cheap 14-50 outlet. Not worth it. Get a Hubbell HBL9450A
Torque the breaker bolts to what is specified on the side of the breaker itself
Torque the outlet to its specs (Hubbell is 75 inch lbs)
Torque the line going into your Tesla Wall Connector to what it shows in the install manual 33 and 16 inch lbs)
Keep an eye on temps - don't always assume things are ok. Most meltdowns I've seen may have been caught earlier if they were watching the temps. Get an IR temp gun so you can see how hot things are - those are very affordable.
I'm planning on doing up to a 3 hour test at 40 amps at some point checking every 30 minutes but that will have to wait until next weekend.
Last edited:
I was seeing a temp rise of about 30F on my breaker after about an hour. I wasn't sure if that was ok or not so I decided to investigate and pass on some info to this thread for others. I found the specs for the breaker I have which is a CH250. It's a CH type 2 pole, 50 amp breaker. I was concerned that it was getting too hot. I found this UL listing test info on it which gives me some confidence that I'm well within the limits of the breaker. Yes, they do get warm. For convenience, here is the particular text for my breaker - others may search for their breakers but I'm guessing most have similar specs.
...and then it goes on to state
So to me, this translates that inside a closed electrical panel, 80% load (40 amps) should not experience a rise in temperature of more than 117F. Key words there are temp rise. If it's already 80F outside and the breaker is also 80F, you don't want the wire terminal point to get more than 197F.
Furthermore, the flat non-metal surface next to the switch itself shouldn't get to more than 197F at 80% load (40 amps). Thats screaming hot. At 40 amps, mine only got to about 130F and it was about 80 degrees outside. The document also said that the plastic material used in making the breaker itself won't begin to break down until about 500F.
So what I'm trying to say is this: Breakers get warm when running them at 80% load. Check the temps and ensure that they're within reason. Don't skimp on the 14-50 outlet and wire either. Just posing all this so that others can learn from it.
Here is the link to the PDF I got that info from: Eaton circuit breakers meet or exceed the strict requirements for heat ...www.eaton.ec/EN/ecm/idcplg?IdcService=GET_FILE...LatestReleased...
"Following the overload test, the circuit breakers are tested at 100% rated current and cannot exceed a 50 °C (90 °F) temperature rise at the wire terminal connection in 40 °C (104 °F) open air. This temperature test may also be performed in an enclosure at 80% rated current and temperature may not exceed 65 °C (117 °F) rise over ambient."
...and then it goes on to state
"The maximum temperature on handles, knobs, and other surfaces subject to user contact during normal operation shall not exceed 60C (140F) on metallic and 85C (185F) on non-metallic surfaces."
So to me, this translates that inside a closed electrical panel, 80% load (40 amps) should not experience a rise in temperature of more than 117F. Key words there are temp rise. If it's already 80F outside and the breaker is also 80F, you don't want the wire terminal point to get more than 197F.
Furthermore, the flat non-metal surface next to the switch itself shouldn't get to more than 197F at 80% load (40 amps). Thats screaming hot. At 40 amps, mine only got to about 130F and it was about 80 degrees outside. The document also said that the plastic material used in making the breaker itself won't begin to break down until about 500F.
So what I'm trying to say is this: Breakers get warm when running them at 80% load. Check the temps and ensure that they're within reason. Don't skimp on the 14-50 outlet and wire either. Just posing all this so that others can learn from it.
Here is the link to the PDF I got that info from: Eaton circuit breakers meet or exceed the strict requirements for heat ...www.eaton.ec/EN/ecm/idcplg?IdcService=GET_FILE...LatestReleased...
darth_vad3r
Well-Known Sith
Good info. I’m not an electrician, but I would expect the breaker to be the warmest part in a properly setup system that’s being pushed hard ... so that the heat build up there trips the breaker before melting or starting a fire elsewhere.
Kleenerth3
Member
Generally, heat = resistance
Heat will not trip a breaker, power surges do. Some great info at the end of this thread.
Do not scrimp on materials, thin wires and cheap connections add to the resistance.
For some reason Romex is not optimum so oversize if you're having to use it.
Good luck and when in doubt, contact a professional.
Heat will not trip a breaker, power surges do. Some great info at the end of this thread.
Do not scrimp on materials, thin wires and cheap connections add to the resistance.
For some reason Romex is not optimum so oversize if you're having to use it.
Good luck and when in doubt, contact a professional.
darth_vad3r
Well-Known Sith
Heat from resistance can and will absolutely trip a breaker. How do you think a breaker trips after a non-power-surge situation like operating a 50A circuit continuously at too high amperage for a long period of time? e.g. over 40A.
The simplest circuit breaker of all, the fuse, operates on heat
Bimetallic strips are a reusable method of heat-triggered circuit breaking.
Modern breakers should react to heat from slow overuse, or from surges or short-circuits via electromagnetic triggers.
Kleenerth3
Member
Thanks Darth. I did over simplify. OP spoke of a hot unit.
Our first house had an old A/C window unit the original owner had fiddled with. The one wire in it wasn't wire nutted, simply taped. Needless to say those wires got hot enough to cause a short and fry the A/C unit. I asked the electrician why the breaker let the unit melt a connection and that's what he told me.
Didn't save the unit but kept the house from burning down.
BTW- keep up the informative posts. I've learned a lot from you and the others on these threads. May the Force be with you!
Our first house had an old A/C window unit the original owner had fiddled with. The one wire in it wasn't wire nutted, simply taped. Needless to say those wires got hot enough to cause a short and fry the A/C unit. I asked the electrician why the breaker let the unit melt a connection and that's what he told me.
Didn't save the unit but kept the house from burning down.
BTW- keep up the informative posts. I've learned a lot from you and the others on these threads. May the Force be with you!
Did some checking on my system today.
Just at dark. Ambient temp around 90 degrees. Wall of house (stone), breaker box, and other breakers read around 96 degrees. All in the shade after 11am (most of day).
Main breaker (200a) read 106 degrees.
50a breaker to HPWC read 115 degrees.
Temp is rising more than I thought. Still easy to touch.
Just at dark. Ambient temp around 90 degrees. Wall of house (stone), breaker box, and other breakers read around 96 degrees. All in the shade after 11am (most of day).
Main breaker (200a) read 106 degrees.
50a breaker to HPWC read 115 degrees.
Temp is rising more than I thought. Still easy to touch.
I researched this quite a bit. Look at the link I posted a few replies up in this thread and it shows what UL tests and what is allowable for the breaker that I have. I know what I have is not what you have, but I would guestimate that they're somewhat similar since they have too adhere to the same safety codes and such. The surface of mine was ~130F. The docs I read also goes on to say that the breaker is safe with a temp rise of up to 117F over ambient. So in my case, it was about 90F outside if I remember right which would allow it to get up to about 207F which would be screaming hot. I think the temps we're seeing are well within the limits and we have to remember that when running the breaker at 80% of max rating, they're going to get warm. I think the key word for me there is warm. I don't think we should touch these things and think "Holy crap, that's really hot!"
. Thats probably too hot and nearing the melting point of things. I also read that the breaker itself, the material they use won't even start to degrade until it gets to the 500F point which is crazy - but good to know they're tough when it comes to handling heat. Hope this helps!I agree all within range. I was thinking mine was cooler, but I never measured it. Just perception to the touch.
The first breaker the electrician installed buzzed lightly and got so hot I couldn’t touch it. I think that biased my view of the temp.
The first breaker the electrician installed buzzed lightly and got so hot I couldn’t touch it. I think that biased my view of the temp.
