Electrical breaker getting warm

[Ormond]

The other day I was charging my Model X with the UMC and NEMA 14-50 outlet that I installed at home. I think I was charging at 40 amps. We noticed a buzzing sound coming from the electrical panel. I could also feel heat coming off the closed panel. I unplugged the charger and the buzzing stopped.

Since that time, I've only been charging while I'm awake so that I can monitor the panel. I also dropped my charging rate to 35 amps. I haven't heard buzzing, but I still feel some heat. I have a 50 amp breaker for the outlet and my panel is full.

I have the electrician who installed the outlet coming back today. Any ideas or suggestions? Is my panel maxed out? Have you experienced the same conditions while charging?

 

[Maximapolak]

Maybe the wires aren't tightened enough.

 

[scottm]

Maybe the wires aren't tightened enough.

...on the breaker itself. And at the receptacle.

Does your UMC plug get warm too?

Or maybe the breaker is bad. Swap for another.
If an electrician put it in, absolutely call them back and make the problem known.

Whatever you do, don't change out the breaker for a higher Amp rating. ( = fire)

Get them to double check the wiring gauge from the panel to the receptacle. It should be a straight run from the panel to plug... no junctions or joins.

 

[habanero69]

The other day I was charging my Model X with the UMC and NEMA 14-50 outlet that I installed at home. I think I was charging at 40 amps. We noticed a buzzing sound coming from the electrical panel. I could also feel heat coming off the closed panel. I unplugged the charger and the buzzing stopped.

Since that time, I've only been charging while I'm awake so that I can monitor the panel. I also dropped my charging rate to 35 amps. I haven't heard buzzing, but I still feel some heat. I have a 50 amp breaker for the outlet and my panel is full.

I have the electrician who installed the outlet coming back today. Any ideas or suggestions? Is my panel maxed out? Have you experienced the same conditions while charging?

You shouldn't get any buzzing from the panel. It could be one of the prior posts like lose connection, bad breaker... assuming you are NOT exceeding your panels rating. Your installed should be called back to check.

I am surprised how hot the UMC cable itself gets when I'm doing a 3-4 hour charge. It is warm enough to almost be uncomfortable at times when handling. Makes me wonder if they are running at the outer limits of the wires/charger.

 

[scottm]

UMC handle where it meets the car degrades in making good contact over time, contacts get dirty ... resistance goes up, makes heat.

Lowering the charging rate (Amperage) helps... but... sometimes you want the speed.

You can try having the handle contacts cleaned using an appropriate electrical contact cleaner... and also clean the contacts in the charge port on the car. Done this a few times in the life of the car... 2 years now.

At some point the charger handle gets too hot, and cleaning does not help. Then it's time to replace the charger. Tesla will do this for UMC under warranty of the car, because it comes with the car.

 

[brkaus]

I had a new circuit 14-50 put in right under my breaker panel. 14" wire. 50a breaker.

Tried charging a demo car. Worked for a few minutes, then cut back to 30a. Eventually tripped breaker.

Reset breaker when I noticed. Started charging and watched carefully. Noticed breaker hot. Heard buzzing sound from breaker. Turned off.

Put in new breaker next day and all was fine. Guess I got a dud.

 

[Ormond]

...on the breaker itself. And at the receptacle.

Does your UMC plug get warm too?

Or maybe the breaker is bad. Swap for another.
If an electrician put it in, absolutely call them back and make the problem known.

Whatever you do, don't change out the breaker for a higher Amp rating. ( = fire)

Get them to double check the wiring gauge from the panel to the receptacle. It should be a straight run from the panel to plug... no junctions or joins.

I didn't notice the UMC being hot, but I did notice an odd smell. Maybe something was burning. I quit charging until the electrician arrives.

 

[scottm]

I didn't notice the UMC being hot, but I did notice an odd smell. Maybe something was burning. I quit charging until the electrician arrives.

smart move

 

[gregd]

What brand of panel do you have? There are some, Zinsco in particular, that are known to fail under load. Really poor design. I have one, and we're replacing it as part of adding the new 14-50 circuit.

 

[brucet999]

As @gregd posted, there are some bad panels out there. Not only Zinsco, but FPE (Federal Pacific Electric), Bulldog Pushmatic, and a few others. If your electrician simply connected to an existing 50A breaker (from an abandoned stove circuit, for example) it could be a bad breaker. If your panel is one of the failure-prone ones and he installed a new breaker it could be an out-of-box failure (FPE had 40
% faulty rate) or the panel itself. My old Zinsco panel was arcing at the breaker/bus connection due to pitted metal on the bus bar. I replaced the panel with Square-D before installing my 14-50 circuit.

 

[Ormond]

My panel was made by Challenger Electrical Equipment Corp. and is about 20 years old. The electrician cam out yesterday and moved some of the breakers around so that the 14-50 outlet had two spaces by itself. The breaker itself still gets hot (175* ) while charging at 40 amps., but it's much better than it was. I may drop down to 35 amps. I am still going to keep a close watch on the panel. The UMC didn't get hot, just warm.

I appreciate everyone's help.

 

[ColdRauv]

Please monitor the temperature of this breaker. If you are measuring temperature at the wire termination, 175 degrees is on the high end of the UL489 testing range, but OK. If you are measuring the temperature on the face of the nonmetallic case, 175 is within 10 degrees of being too hot and indicates a problem. Has this breaker tripped on you yet? High heat will trip a breaker at a lower current.

 

[DarkMatter]

If your panel is getting that hot I would not trust it with a high continuous load such as EV charging. If I were in your spot I would switch to charging with a 14-30 so you limit to 24 amps, or maybe buy the Canadian 14-50 adapter which automatically limits to 32 amps instead of 40.

Long term you should put in a panel which is not obsolete. Breakers for Challenger panels are listed as an obsolete type. Of course that can be moderately expensive so I understand if you're in no hurry to do it. Limit the current in the meantime until it doesn't get so hot. Having to replace a panel on short notice because of a burned bus bar is no fun. BTDT.

 

[Ormond]

If your panel is getting that hot I would not trust it with a high continuous load such as EV charging. If I were in your spot I would switch to charging with a 14-30 so you limit to 24 amps, or maybe buy the Canadian 14-50 adapter which automatically limits to 32 amps instead of 40.

Long term you should put in a panel which is not obsolete. Breakers for Challenger panels are listed as an obsolete type. Of course that can be moderately expensive so I understand if you're in no hurry to do it. Limit the current in the meantime until it doesn't get so hot. Having to replace a panel on short notice because of a burned bus bar is no fun. BTDT.

I'll drop it to 32 amps. I was measuring the temperature of the breaker itself.

 

[tga]

IMHO, 175 is too hot. Something is wrong, and you should get it checked out. My old solar system routinely pushed 32-34A through a 40A backfeed breaker (GE). It would get noticeably warm, but I could hold my hand on it without discomfort. I think I was seeing ~105F with an IR thermometer.

 

[Ormond]

IMHO, 175 is too hot. Something is wrong, and you should get it checked out. My old solar system routinely pushed 32-34A through a 40A backfeed breaker (GE). It would get noticeably warm, but I could hold my hand on it without discomfort. I think I was seeing ~105F with an IR thermometer.

I'll measure it again and drop the amps. I don't mind charging more slowly. I may also change electricians

 

[uhhuh7977]

Ormond...how did you resolve your issue? I have the same problems with charging my MX.

The first time I actually noticed the issue was when I my MX didn't charge and while troubleshooting I found my breaker completely burnt. Since then, I replaced the breaker and pulled new wires. I started monitoring my panel since then and just like you it gets hot and the breaker buzzes and the wires are also vibrating. I had SC look into the car and the logs showed that there is something weird going on with the car while charging. They offered me a new charger to try out but still my breaker was getting warm (>100F) while charging at 40 amps.

Now, I always set my MX to charge at 25 amps and the breaker stays at ambient temperature. I am paranoid of setting it back to 40 amps. I am thinking of trying to do it today during the holiday and see how hot it really gets at 40 amps and see if its starts buzzing again (I noticed it started buzzing after a while, not immediately).

Hope you can share how your charging experience is now and what have you done to resolve you charging issue. TIA!

 

[richrootes]

Holy S - I’d say you’re pretty lucky you didn’t have a fire

Is everything ok now though?

 

[uhhuh7977]

Holy S - I’d say you’re pretty lucky you didn’t have a fire

Is everything ok now though?

Tell me about it! I even showed this to an electrician whom I know and he said he has never seen a breaker burnt like that in his life! I am now charging with the new charger from SC and no vibration yet and IR thermometer shows 108F. 1 hour charging now. So far nothing alarming yet.

 

[brkaus]

I think you had a faulty breaker or worn bus bar in the panel. Very scary. I had two bad breakers.

When you said “new charger” do you mean the wall connector, evse, or the actual charger in the car?

Pretty lucky. When I was growing up, we had a breaker fail and it dropped hot metal and shorted across two buss bars causing them to explode.