EV Tesla Chargers melting breakers

Status
Not open for further replies.
It's not only Tesla chargers, I've seen this happen with other high amperage equipment connected to plug-in breakers (i.e AC units, electric ovens and walk-in box refrigerators. The jaws inside the breaker aren't making good contact with the buss. How old is the panel ? Perhaps using an anti-oxident on the buss might prevent this in the future. Just a thought.
 
Frank DuVal said:
Another example of why breaker panels should NOT be in an outside environment. Our indoor breaker panels look fine for 40+ years as long as the basement is not wet... ;)
Click to expand...
anyone remember those wierd panels sqd made that was all one piece with a meter/main on the outside wall and a loadcenter on the inside wall?
 
goldstar said:
It's not only Tesla chargers, I've seen this happen with other high amperage equipment connected to plug-in breakers (i.e AC units, electric ovens and walk-in box refrigerators. The jaws inside the breaker aren't making good contact with the buss. How old is the panel ? Perhaps using an anti-oxident on the buss might prevent this in the future. Just a thought.
Click to expand...
We discussed Aluminum Buss panels a few months ago here on this forum. I believe a certain type of anti-oxidant is specified by some plug-in aluminum buss panel manufacturers whenever installing a breaker.
The best buss is a bolt-on buss and second to that may be a Siemens copper buss.
 
Looks to be a Challenger, or Westinghouse/C-H/Eaton, BR, panel so your dealing with a bottom of the line product, as to installing a panel outdoors, had the opportunity to make changes to a Gould/ITE panel I installed in 1980, primarily to remove decommissioned circuits, remove any non ITE or Siemens breakers, the breakers had a dab of noalox used prior to being plugged in & the bus stabs were still in great shape, was interesting because know the history of it & is mounted on the north side of the building so a little more damp during winter. Not so sure about the use of noalox when installing plug in breakers in aluminum bussed panels anymore, have come across where it's been used and acts as a adhesive requiring they be literally be pried out which is not a good thing & could lead to serious consequences if done with a live bus.
 
I've seen where the old panels mentioned and the Cutler Hammer (pre Eaton) the breakers and or mains will not trip in a short or overload condition and would lead to the meltdown shown. Seen that happen right infront of me after warning homeowner that panel/breaker had an issue and needed replacement.
The only thing I've seen with a Tesla charger is installer or homeowner adjustment to the capacity of the charger trying to get a faster charge created an overload condition and the faulty breaker wouldn't trip as needed and resulting catastrophic failure like above. Not a charger issue directly.
 
I also agree that panel looks like maybe has some age.

On top of that most dwellings have few circuits that see much loading other than for short time. HVAC equipment maybe the most common item that runs for any significant amount of time. Maybe a pool pump is right up there with HVAC equipment. Most everything else doesn't run for very long at a time and never heats things up enough to matter much. Now we are adding more of these EV chargers and many draw even more than the HVAC or pool pumps do. They may not run for as long of periods as the HVAC or pool pumps but they often do run for significant amount of time.

Until these came about you could always go into a pretty new home installation when the air conditioning been running and the AC breaker would be warm to touch but all others are not.

Go into some non residential places and you might find many breakers that are warm simply because the load is rather continuous on those circuits, where the residential you mostly only found this with HVAC and maybe pool pump breakers.
 
kwired said:
On top of that most dwellings have few circuits that see much loading other than for short time. HVAC equipment maybe the most common item that runs for any significant amount of time. Maybe a pool pump is right up there with HVAC equipment. Most everything else doesn't run for very long at a time and never heats things up enough to matter much. Now we are adding more of these EV chargers and many draw even more than the HVAC or pool pumps do. They may not run for as long of periods as the HVAC or pool pumps but they often do run for significant amount of time.
Click to expand...
People that are into pottery making sometime have their own electric kiln, which runs for hours at a time. I've seen several burnt and melted NEMA 6-50 plugs and receptacles.
 
BarryO said:
People that are into pottery making sometime have their own electric kiln, which runs for hours at a time. I've seen several burnt and melted NEMA 6-50 plugs and receptacles.
Click to expand...
yes, but other than initial warm up, they still only cycle as needed to maintain temperature, so they are not actually pulling heavy current for that entire "run time". Next question is whether the plug/receptacle actually failed or if a poor termination to either is what actually started the failure?
 
BarryO said:
People that are into pottery making sometime have their own electric kiln, which runs for hours at a time. I've seen several burnt and melted NEMA 6-50 plugs and receptacles.
Click to expand...
I'm in the process of installing a kiln receptacle at my house right now, for my wife. She says due to the long run time and high amp draw, it would be nice to rate the circuit for 60 amps, but the cord cap provided with the kiln is a NEMA 6-50.
 
Mr. Serious said:
I'm in the process of installing a kiln receptacle at my house right now, for my wife. She says due to the long run time and high amp draw, it would be nice to rate the circuit for 60 amps, but the cord cap provided with the kiln is a NEMA 6-50.
Click to expand...

If it’s supplied with a 6-50 plug, I’d expect the max current rating to be no more than 40A on a continuous load. Do you have the specs (or nameplate)?
 
retirede said:
If it’s supplied with a 6-50 plug, I’d expect the max current rating to be no more than 40A on a continuous load. Do you have the specs (or nameplate)?
Click to expand...
Do you have a specific NEC or UL reference that says the ampere ratings of receptacles, plugs, and cords are not continuous ratings? I've wondered about that but a quick look didn't turn anything up for me.

Cheers, Wayne
 
kwired said:
yes, but other than initial warm up, they still only cycle as needed to maintain temperature, so they are not actually pulling heavy current for that entire "run time". Next question is whether the plug/receptacle actually failed or if a poor termination to either is what actually started the failure?
Click to expand...
I believe that, to provide a smooth ramp up of temperature to avoid cracking the pottery or glaze, the heating elements are "underpowered" to the extent that they will be drawing full current over a substantial time period before reaching operating temperature and starting to cycle.
The kiln is very well insulated and has a considerable thermal inertia. The combination of insulation and thermal inertia is necessary to allow a controlled cool down, again to prevent cracking of the pottery.
(Or does the kiln controller actively ramp down the heat input during the cooling cycle?)
 
My wife is just getting into pottery again, and last time she always had someone else's kiln available, so I really don't know much about them yet. But I know the newer controls are electronic, but the older ones had more of an electro-mechanical control. The control is called a kiln-sitter, and that's usually the most prominent name on the whole kiln, so if you see someone selling a "kiln-sitter" brand kiln, it means the seller doesn't know kilns, because that's only the brand of the control.
I believe the kiln sitter has a timer switch built in, three outputs for the three heating elements. The kiln sections are stacked, the bottom one with the kiln sitter control on it, the middle and upper sections have heating elements only. The temperature is ramped up slowly by turning on first one element, then two, then all three. The kiln sitter also has a little switch extending into the kiln itself, that you set a cone of wax on, and when the wax melts, the switch is opened and the kiln turns off. You use different cones of wax for different maximum temperatures. That's the extent of my understanding of it.
I didn't finish wiring the circuit yet, so we haven't tested her kiln yet. I will try to find any amp ratings listed on it.
 
All the classic Kiln-sitter does is shut off power once a certain temperature is reached (as indicated by the "cone" sagging over). Every ceramic kiln I've seen uses well-insulated thermal mass to ramp down the temp, sometimes over a couple of days. (Same for glass annealing ovens.)

As for firing, also all the ones I've seen fire/heat continuously until hitting the target temp. Some have multiple elements and will start with only one to drive off moisture, but after that it's all-on to get to temp. as fast as reasonably possible. No on/off controls other than the main switch.

In the end, I'd definitely consider a ceramic kiln as a continuous load.
 
Status
Not open for further replies.
Top