Almost Burned my House Down... Thoughts / Theories?

[mongo]

note: that looks like aluminum wire to me. Not sure why tf anyone in their right mind would would be using that for an EV charger. Prone to disasters just like this.

There is no issue using properly sized and terminated aluminum wire in an EVSE branch circuit.
Meters are fed with Al, main panels are fed with Al, subpanels are fed with Al, other high current loads are fed with Al. As long as they didn't make the error of landing the conductors in the Wall Connector, it's a lower cost option for long runs.

Doing it wrong 100 times then. Unless someone can correct me, I can't find a single engineering reason to do this. Coiling wire INCREASES the thermal mass load; not the other way around.

It increases the total heat output from the wire in the box, but it reduces the transfer of heat generated by the connection. For a short run, it might reduce peak temperature, doubtful it is needed though.

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[mongo]

Is your setup for the two chargers one master and one slave in group power management?
when I first installed my current chargers, this wasn’t set incorrectly in Tesla one and both tried to draw 48 amps despite them being on the same 60 amp breaker.

Good thing to check; but wouldn't have caused this failure.
The meltdown was at the single WC feed though. A GPM misconfiguration would trip the breaker and/or overload the connections shared by the WCs.
In this situation, the second WC wasn't in use at time of failure, but might have been earlier.

 

[REM]

There is no issue using properly sized and terminated aluminum wire in an EVSE branch circuit.
Meters are fed with Al, main panels are fed with Al, subpanels are fed with Al, other high current loads are fed with Al. As long as they didn't make the error of landing the conductors in the Wall Connector, it's a lower cost option for long runs.

It increases the total heat output from the wire in the box, but it reduces the transfer of heat generated by the connection. For a short run, it might reduce peak temperature, doubtful it is needed though.

Yep. You would have to run a significant amount of excess wire for that to make any practical difference. far more likely to cause problems.

 

[mongo]

Yep. You would have to run a significant amount of excess wire for that to make any practical difference. far more likely to cause problems.

Yeah, like mechanical fatigue from the loop vibrating at 60Hz. It's cool to see photos of high power equipment with the feeds tied up with twine to avoid cables jumping around if there is a fault.

 

[NotMyTruck]

I too think it’s possibly two chargers on the same breaker.

Hopefully OP comes through with the full story and the culprit.

 

[Trekboy]

Electrician is suspect in my book as he didn't bother to put a plastic bushing on the threaded end of this metal conduit.

 

[NotMyTruck]

@Carlos Thomas. In my opinion, installation is very straightforward, but there’s room for error due to inexperience. Since we’re all thinking it. I’ll ask - can you comment on:
1. What gauge wire was used?
2. Single strand or romex?
3. Breaker size?
4. Total amps going to the house?
5. Total amps on the panel with tesla breaker(s)
6. Assuming you have two breakers - are both on the same panel?
7. Total length of the wire run, per charger
8. Amperage setting per charger.
9. Amperage setting per vehicle.
10. Number of poles, per circuit breaker
11. Assuming single strand - what conduit was used?
12. What is the inner diameter of the conduit, per charger?
13. Is any part of the installation outside? If it is, what cable was used?

Any reputable installer should be able to provide a bill of materials (BOM) to help clarify most things in the list.
What did I miss

 

[hemiarch]

Good thing to check; but wouldn't have caused this failure.
The meltdown was at the single WC feed though. A GPM misconfiguration would trip the breaker and/or overload the connections shared by the WCs.
In this situation, the second WC wasn't in use at time of failure, but might have been earlier.

So I see exactly where you’re coming from except in my case I smelled burning and the UWC sent out a rainbow error code prompting me turning off the breaker when it happened.
You would think that the 60 amp breaker would trip at 61 amps (otherwise why the hell is it there?) but that’s not what happened.
Electricians who didn’t install exactly to code came to inspect and said everything looked fine in the box but I still made them go to Home Depot, purchase a new 60amp breaker and change it out because I was so convinced what was supposed to happen did not.
Tesla could not help me log into the UWC and sent out a replacement.
After replacing the charger I sent that first one to our Canadian electrician friends from this forum who went through the wall connector with a fine tooth comb and said everything was ok with it. They reset it somehow and sent it back resulting in my having a spare.
My software is set correctly now and I’ve had no issues, but it still shook my faith in the system that I could smell burning and see both cars at least attempt to get 48 amps whenever that happened.

 

[REM]

Electrician is suspect in my book as he didn't bother to put a plastic bushing on the threaded end of this metal conduit.

technically agree here, but this is probably just a nit-pick. I don't install those either if I have a proper burr free bushing

 

[mongo]

So I see exactly where you’re coming from except in my case I smelled burning and the UWC sent out a rainbow error code prompting me turning off the breaker when it happened.
You would think that the 60 amp breaker would trip at 61 amps (otherwise why the hell is it there?) but that’s not what happened.
Electricians who didn’t install exactly to code came to inspect and said everything looked fine in the box but I still made them go to Home Depot, purchase a new 60amp breaker and change it out because I was so convinced what was supposed to happen did not.
Tesla could not help me log into the UWC and sent out a replacement.
After replacing the charger I sent that first one to our Canadian electrician friends from this forum who went through the wall connector with a fine tooth comb and said everything was ok with it. They reset it somehow and sent it back resulting in my having a spare.
My software is set correctly now and I’ve had no issues, but it still shook my faith in the system that I could smell burning and see both cars at least attempt to get 48 amps whenever that happened.

Breakers have a time to trip specification (thermal based) along with temperature variation along with fast acting high current fault detection (magnetic based). 61A on a 60A breaker may never trip.

Was the second WC daisy chained through the one that failed?

 

[Carlos Thomas]

As an update, they installed an emergency disconnect box and make a cleaner connection etc. Nothing happened to the Tesla Wall Connector, but they are replacing both.

 

[NotMyTruck]

An emergency disconnect? For what

 

[Carlos Thomas]

@Carlos Thomas. In my opinion, installation is very straightforward, but there’s room for error due to inexperience. Since we’re all thinking it. I’ll ask - can you comment on:
1. What gauge wire was used?
2. Single strand or romex?
3. Breaker size?
4. Total amps going to the house?
5. Total amps on the panel with tesla breaker(s)
6. Assuming you have two breakers - are both on the same panel?
7. Total length of the wire run, per charger
8. Amperage setting per charger.
9. Amperage setting per vehicle.
10. Number of poles, per circuit breaker
11. Assuming single strand - what conduit was used?
12. What is the inner diameter of the conduit, per charger?
13. Is any part of the installation outside? If it is, what cable was used?

Any reputable installer should be able to provide a bill of materials (BOM) to help clarify most things in the list.
What did I miss

I am not an electrician, but here are my best answers:

1) 6 gauge wire
2)
3) 60 amp breaker
4) 400 amp service (Two 200 amp panels)
5) Two 200 amp panels with 1 Tesla Wall Charger on each panel
6) Separate Panels
7) I estimate maybe 40 feet tops
8) 48 amps
9) 48 amps
10)
11)
12)
13)

I answered the ones I could.

Here are two more photos of the carnage. They believe the culprit was the piece that is in my Wife’s hand and it arched.

 

[hemiarch]

Breakers have a time to trip specification (thermal based) along with temperature variation along with fast acting high current fault detection (magnetic based). 61A on a 60A breaker may never trip.

Was the second WC daisy chained through the one that failed?

Yes. It was. The screen for the first car said 48/48. The second car was ramping up when I started smelling something but the denominator was also 48. I then went to go disable the breaker but by the time I got there charging was stopped and the rainbow code showed up on the primary UWC.
then I couldn’t access that charger through either the Tesla app or Tesla one at all

 

[Carlos Thomas]

An emergency disconnect? For what

Two reasons:

1) Allows for a cleaner connection (main reason)…more room.

2) If I need to shut it off, I don’t have to walk all the way around the side/back of the property. (Not as important)

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