Electrical Gurus - overloading c/b with PMCC

[Novemberwhisky]

Overnight charging recently i found my c/b tripped every night. The PMCC unit was set to the max 32A charging load. Opened up the connectors to find scorching of the cables and connectors on the charger side of the circuit. The insulation on the lower wires is glazed and shows signs of overheat. Though the insulation is not visually compromised. Cables look to me sufficent to cope with the load - approx 3mm diameter core.

my electrician scratched his head - must be a fault with the PMCC unit. Took it to porsche and they checked and said all is ok it must be an upstream fault, (my unit was not subject to recall)

so why is the c/b tripping at 32A? It appears a thermal overload. I set the PMCC to 20A and charging is fine, no interruptions. my bro diagnostic was to gradually increase the charging load and see what it tripped at. Settled on 20A, and all now seems fine.

last winter it was charging ok at 32A. Is the c/b and wiring now compromised so as to be unable to cope with higher loads?
i am going to swap in a new c/b and wires.

my electric knowledge is sketchy so any suggestions welcome

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[W1NGE]

Overnight charging recently i found my c/b tripped every night. The PMCC unit was set to the max 32A charging load. Opened up the connectors to find scorching of the cables and connectors on the charger side of the circuit. The insulation on the lower wires is glazed and shows signs of overheat. Though the insulation is not visually compromised. Cables look to me sufficent to cope with the load - approx 3mm diameter core.

my electrician scratched his head - must be a fault with the PMCC unit. Took it to porsche and they checked and said all is ok it must be an upstream fault, (my unit was not subject to recall)

so why is the c/b tripping at 32A? It appears a thermal overload. I set the PMCC to 20A and charging is fine, no interruptions. my bro diagnostic was to gradually increase the charging load and see what it tripped at. Settled on 20A, and all now seems fine.

last winter it was charging ok at 32A. Is the c/b and wiring now compromised so as to be unable to cope with higher loads?
i am going to swap in a new c/b and wires.

my electric knowledge is sketchy so any suggestions welcome

No expert either but did Porsche also check the PMCC to power socket cable in case it has been compromised in some way?

I've had a faultless PMCC on 32A since Nov'21 but we don't get hot summers so it's never been stressed at all.

 

[enzo5000]

I'm no expert either. What gauge wire is going in and out of the 32a. breaker? It should be 8 gauge. If it's 10 gauge it'll probably overheat.

 

[j_scheetz]

I am a backyard electrician. As far as I understand you should not run more than 85% of your wire/breakers capacity. For 32A of charging, I would assume a 40 amp breaker and wire rated for 40 amps. For my 40 amp charger, I have a 50 amp breaker and #6 wire.

Real electricians, please weigh in....

 

[daveo4EV]

I'm no expert either. What gauge wire is going in and out of the 32a. breaker? It should be 8 gauge. If it's 10 gauge it'll probably overheat.

OP is european - different standards and requirements.

 

[daveo4EV]

I am a backyard electrician. As far as I understand you should not run more than 85% of your wire/breakers capacity. For 32A of charging, I would assume a 40 amp breaker and wire rated for 40 amps. For my 40 amp charger, I have a 50 amp breaker and #6 wire.

Real electricians, please weigh in....

OP is european - I personally barely understand north american requirements - I avoid providing euro-advice on electrical matters - they run things slightly different over there.

 

[Novemberwhisky]

I'm no expert either. What gauge wire is going in and out of the 32a. breaker? It should be 8 gauge. If it's 10 gauge it'll probably overheat.

Thats interesting. I did some background reading and understand AWG is different to european spec but it makes sense that a 32A load would need a higher protection and cable diameter.

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