Almost a fire while charging

[AB4EJ]

Here is a cautionary tale. We installed a new 50 amp breaker pair (by "we," I mean I hired a licensed electrician) for Tesla charging (this is in Florida). The new circuit seemed fine and had been used to charge Teslas on a number of occasions. However, in this incident, after charging my MS at 40 amps for a couple of hours, I got a notification "Charging Interrupted." Upon investigating, there was a stench in the room where the circuit panel is (odor of burning plastic), and the circuit breaker was too hot to touch. (It had apparently tripped due to thermal overload). The other set of breakers on the same panel pin was also very hot (this other one is a 60 amp breaker for the house A/C).

Opening the panel, we see that the panel backplane was scorched on the right, and the two breakers were burned:

Why did this suddenly happen? We called in the electrician who did the work, who said there was some corrosion on the pins where the breakers plugged in; these he cleaned with a wire brush and replaced the breakers. (He suggested replacing the entire panel, and by "coincidence" his company was running a special deal on this, only $1487!)

My own post-mortem suggests an alternate explanation... this happened suddenly because this was the first time we had charged a Tesla during warm weather where the A/C was running constantly on the same panel pin. Could it be that these panel pins cannot support this continuous load (totaling 88 amps, i.e., 48 a on the 60-a breaker, and 40 a on the 50-a breaker)? Upon closer inspection, it appears to me as though the breaker the electrician originally put in for the new Tesla circuit was not a new one, but might have been a used one pulled from somewhere else (I say this because the switch on that breaker appears to have been snapped off and repaired with epoxy). In that case, maybe the contacts where the breaker connects to the panel pin had lost their strength and did not make a tight connection to the panel backplane....

So all you electricians in the group: can a single pin on a 200 a panel handle a continuous load of 88 a? If not, it is just a design problem, and the Tesla breaker should simply be moved in the panel so that it does not share a pin with the A/C breaker. If these pins can indeed support this kind of load, then maybe the panel does have corrosion, suggesting a replacement. Thoughts?

 

[boaterva]

I can't tell from looking at that pic, but I wonder if the panel is one of the ones that have been discussed as 'should be replaced ASAP'? Can you tell us the brand of the panel and the breakers? That's one idea.

But a used breaker is a definite no-no, especially at the high currents and loads we're talking about here! (And, hello from a fellow EE!)

 

[CuriousG]

So all you electricians in the group: can a single pin on a 200 a panel handle a continuous load of 88 a? If not, it is just a design problem, and the Tesla breaker should simply be moved in the panel so that it does not share a pin with the A/C breaker. If these pins can indeed support this kind of load, then maybe the panel does have corrosion, suggesting a replacement. Thoughts?

I'm not sure if he's still around but @FlasherZ is the resident expert electrician that should be able to answer your question.

Just checked his last login activity and he was last seen over a month ago.

 

[fwgmills]

I know it's expensive, but you might want to replace the entire panel. It looks corroded on both the hot legs and the neutral. Perhaps the Florida weather has taken it's toll. I would look at that panel and assume that all the connections to the breakers are suspect. Plus a possible used breaker...definitely hire a different electrician to do any future work.

 

[AB4EJ]

I can't tell from looking at that pic, but I wonder if the panel is one of the ones that have been discussed as 'should be replaced ASAP'? Can you tell us the brand of the panel and the breakers? That's one idea.

But a used breaker is a definite no-no, especially at the high currents and loads we're talking about here! (And, hello from a fellow EE!)

The panel and breakers are Siemens. Is that one of the ones with the problem? I thought the Federal Pacific Stab-Lok were the ones with the problems; or are there additional problematic ones?

 

[boaterva]

Just as a data point, my 100 Amp breaker (for a circuit with two load-balanced HPWCs) is right across from a 60 Amp breaker for my hot tub (excuuuse me, 'spa'). I've had the HPWC at 48 Amps, and the hot tub was probably heating, not running full bore. The electricians (Tesla-approved... ), didn't think anything about putting them 'next' to each other. For what that's worth.

 

[boaterva]

The panel and breakers are Siemens. Is that one of the ones with the problem? I thought the Federal Pacific Stab-Lok were the ones with the problems; or are there additional problematic ones?

Two seconds googling found a recall for some from 2010, but I really doubt your panel is only seven years old..

I'm thinking (but I'm no electrician, either, just what I know from EE and practical experience) that most of the problem may be from age and that 'reused?' breaker.

Flasher could definitely have an expert opinion if he has a chance; you might want to take a look at his FAQ (see my sig) if you've not already.

 

[jelloslug]

This is another example on why I rarely call "professionals" to do work for me.

 

[Xenoilphobe]

I was worried my 200 AMP panel which was 25 years old with additional loads added over the 25 years: pool, in-law kitchen and additional electric dryer added was just a mess, so when we did the solar upgrade, I had them replace the 200 AMP Panel with a 400 AMP Square D panel and had the electrician clean up the the poor wiring jobs. Then we added another Square D 200 AMP Panel in the garage just for the Teslas...just to be safe... don't wanna burn my house down!

 

[jelloslug]

I was worried my 200 AMP panel which was 25 years old with additional loads added over the 25 years: pool, in-law kitchen and additional electric dryer added was just a mess, so when we did the solar upgrade, I had them replace the 200 AMP Panel with a 400 AMP Square D panel and had the electrician clean up the the poor wiring jobs. Then we added another Square D 200 AMP Panel in the garage just for the Teslas...just to be safe... don't wanna burn my house down!

Do you have a 400 amp service to the house?

 

[Lloyd]

I'd say it is the electricians fault for using used or faulty parts, and not cleaning the contact where the breaker is terminating. Your panel is fine IMO and just needs some maintenance. Additionally, he should have checked the work under load before he left.

 

[jeffro01]

I'm not enough of an expert to know what happened from looking at the pics but given your comments from the electrician about corrosion, I'd be getting an attorney if I were you... Assuming you're inclination is accurate, a licensed electrician installed a used breaker drawing a continuous load in a panel where corrosion existed to the point of requiring cleanup before the new circuit was added. If that is a factual statement then what the electrician did was wrong on so many levels...

Get an attorney...

Jeff

 

[AB4EJ]

I'd say it is the electricians fault for using used or faulty parts, and not cleaning the contact where the breaker is terminating. Your panel is fine IMO and just needs some maintenance. Additionally, he should have checked the work under load before he left.

I agree; he did use a wire brush to clean the contacts that had overheated (this really should be done to all contacts in the panel). It was not possible for him to check under full load at original installation, because didn't have a Tesla available to put 40 a load on the new breaker.

One of my solutions here, even assuming that the cleaned contacts and replacement breaker are fine, will be to charge at 20 A instead of 40 A (feel free to disagree with this, as I disagree with myself on this point).

I'm not enough of an expert to know what happened from looking at the pics but given your comments from the electrician about corrosion, I'd be getting an attorney if I were you... Assuming you're inclination is accurate, a licensed electrician installed a used breaker drawing a continuous load in a panel where corrosion existed to the point of requiring cleanup before the new circuit was added. If that is a factual statement then what the electrician did was wrong on so many levels...

Get an attorney...

Jeff

Regarding "Get an attorney...." - are you an attorney? I'm not sure what legal action would be called for, since the electrician came over and made repairs for just the nominal cost of a service call ($120). It would cost me more than that for just the first discussion with an attorney about this matter...

 

[BrettS]

One of my solutions here, even assuming that the cleaned contacts and replacement breaker are fine, will be to charge at 20 A instead of 40 A (feel free to disagree with this, as I disagree with myself on this point).

I think it just comes down to you being able to sleep at night while your car is charging. If you don't trust it at 40A, then can you still trust it at 20A?

In the end, you didn't have a fire (and it sounds like the circuit breaker tripped, so it did it's job and prevented this from turning into a fire) but if you don't trust it then you should probably do whatever that takes to make sure that you do trust it. That could be hiring another electrician to just check everything and make sure he thinks it's good, replacing the whole panel so you know there are no issues, or just charging the car while you are home and awake and can monitor it every 20 or 30 minutes for a while. Or charging at 20A instead of 40A.

But in the end as long as you're happy that you can trust it and you can sleep at night then I think that's all you need to do.

 

[jeffro01]

Regarding "Get an attorney...." - are you an attorney? I'm not sure what legal action would be called for, since the electrician came over and made repairs for just the nominal cost of a service call ($120). It would cost me more than that for just the first discussion with an attorney about this matter...

Nope... But, IMHO, you're insane for allowing the same electrician who did an improper install in the first place back to do it again... Again, my position is based on your presentation of the facts which included the presence of a corroded electrical panel back plane and the installation of a used breaker. After this incident, I wouldn't have allowed that electrician to step within 50 ft of my house if I were you.

Jeff

 

[Doug_G]

I had a 60A cutout switch melt, which I first noticed because of a smell in the garage. This was after four years of nightly operation at 40A. I suspect the electrician had not tightened the screws firmly enough when he installed it, and they must have been running hot. Eventually they were damaged and the conductivity started dropping, leading to even more heating.

I replaced the switch with another identical unit, and made sure to firmly tighten the screws. I am now going to open the box and inspect it every month or so.

On the other side of the garage, I have a 7 year old 90A Roadster HPC, which is usually run at 40A (70A on occasion). I've had no trouble with it whatsoever.

Perhaps it's a good idea to not use full circuit capacity unless you need a faster charge...

 

[AB4EJ]

Nope... But, IMHO, you're insane for allowing the same electrician who did an improper install in the first place back to do it again... Again, my position is based on your presentation of the facts which included the presence of a corroded electrical panel back plane and the installation of a used breaker. After this incident, I wouldn't have allowed that electrician to step within 50 ft of my house if I were you.

Jeff

That's probably good advice, but we already had him back (same goofy guy) because we needed the circuit to charge the car; also, at the time, I didn't have any inkling that he might have installed a used breaker when he put the original circuit in (I reached this conclusion only after a close examination of the burned breaker he took out, which appeared to have been repaired with epoxy). However, I closely observed what he did, and will probably go back myself and replace the circuit breakers he put in with ones that I buy new from supply house, in case he installed used breakers again. In the meantime, it is really no problem to charge at a reduced rate.

Having said all that, I understand that corrosion in electrical panels is not uncommon in Florida (this panel was in a garage), they do a brisk business in replacing these; so it is still possible that the electrician did nothing wrong.... I think one would be hard pressed to prove it one way or the other.... I will just use a different company for future work...

 

[jeffro01]

That's probably good advice, but we already had him back (same goofy guy) because we needed the circuit to charge the car; also, at the time, I didn't have any inkling that he might have installed a used breaker when he put the original circuit in (I reached this conclusion only after a close examination of the burned breaker he took out, which appeared to have been repaired with epoxy). However, I closely observed what he did, and will probably go back myself and replace the circuit breakers he put in with ones that I buy new from supply house, in case he installed used breakers again. In the meantime, it is really no problem to charge at a reduced rate.

Having said all that, I understand that corrosion in electrical panels is not uncommon in Florida (this panel was in a garage), they do a brisk business in replacing these; so it is still possible that the electrician did nothing wrong.... I think one would be hard pressed to prove it one way or the other.... I will just use a different company for future work...

Understood. I don't mean to come off as being mean or anything but when dealing with continuous loads poor connections create resistance which creates heat which creates fire eventually. Corrosion on metal components is certainly a common thing in humid climates, no doubt there, but if you're going to install a continuous load on a panel that is exhibiting that normal condition in your climate setting better be damn sure they sufficiently cleaned the contacts. The used breaker stuff is really unsettling to me which is why I gave you such a strong reaction. When you do swap it out, be sure to sufficiently tighten the screws on your new breaker then check them again in a month and re-torque as needed.

Most electricians I have come in contact with, expect for the one I use exclusively for this kind of work, don't fully appreciate the concept of a continuous load as most residential applications don't have a continuous load that may be taking up to 50% of the panel capacity at any given time so they don't take the torquing or the screws or condition of the back plane seriously enough when doing the work....

Jeff

 

[mspohr]

I'm not enough of an expert to know what happened from looking at the pics but given your comments from the electrician about corrosion, I'd be getting an attorney if I were you... Assuming you're inclination is accurate, a licensed electrician installed a used breaker drawing a continuous load in a panel where corrosion existed to the point of requiring cleanup before the new circuit was added. If that is a factual statement then what the electrician did was wrong on so many levels...

Get an attorney...

Jeff

This is not something that an attorney will "solve". Attorneys know nothing about electricity. They only know how to bluff (and charge $ not batteries).
It's a simple problem of overheating of the panel tab and/or circuit breakers. They need to be replaced. (Probably wasn't a good idea to put two high amp circuits next to each other on the same panel tab)
You can spend a few thousand on an attorney or just have an electrician fix it (for less) and move on with your life.
Looks like you have a lot of corrosion in your panel (? Florida problem) so might be a good idea to fix it.
Just be glad that the equipment did work; it broke the circuit and your house didn't burn down.
Siemens equipment is good and has not been subject to recall.