48Amp EV charger melting breakers

[ash_sweep]

ran into a crazy service call today. the customer smelled that an electrical burn just a week after their 48amp Wallbox install.
I showed up and find the 60A breaker completely melted, but still powered on!
everything looked perfect on paper. I checked the Polaris taps, the energy management module, and all the connections
everything was torqued to spec with no signs of arcing

then I bypassed the module and installed a brand new breaker to rule out a fluke. we verified 48 amps on each leg with perfect voltage at the car and the panel. within minutes, the burning smell was back and the new breaker started overheating immediately.
my manager and engineer are confused. we're replacing the whole panel for free to be safe, but I’ve never seen a setup bypass all the math and just cook like this.
has anyone else dealt with a panel busbar failing under a steady EV load, even when the connections are tight? what are we missing?

 

[blondrob]

hi Ash, have you tried moving it to a new breaker on a different section of the bus bar?

 

[ash_sweep]

hi Ash, have you tried moving it to a new breaker on a different section of the bus bar?

yeah, no overheating anywhere else in the system

 

[cream5oda]

this happens more than you know. especially when someone tries to side load a ton of solar panels onto a 100A main panel. honestly, it's just asking for trouble

 

[PGB1]

Does this charger use a neutral from the load center? If so, perhaps check it's connections.

Twice I ran into circuit breakers for EV chargers very, very hot- to the point of melting plastic odor. Studying showed that the neutral was also hot and the connection at the neutral bus was hot. Reason? Harmonics due to non-linear loads of the electronics.

I used to work in an NFL stadium where RV shows were put on. The neutral from the 600 kVA transformer to temporary distribution would get quite hot. The circuit breakers for loads in the temporaries would get hot. We doubled the neutral size from the mains to the temporary distribution panels & from the temporary panels to the individual circuits. Reason? Harmonics due to electronic chargers.

This was also done for large concerts which had large load amplifiers.

Doubling the neutral size solved the hot circuit breaker problems in each situation.

Hopefully this will provide you with an easy fix.
Paul