I believe mentioned earlier. This is why the Tesla mobile connector (gen2) has thermal sensor in the plug. This would have been detected and the thread title would have been “why is my charging slowing down and/or cutting out”
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What do you think caused this electrical fire?
- Thread starter EatsShoots
- Start date
legendsk
Member
That reminds me, airplanes were made of sticks and cloth until aluminum got cheap. Then they quickly became 80% aluminum and now are down to 20% because of composites. Real estate is so expensive on boats or planes, wiring would be copper, just for the weight and space savings if nothing else.
It gets complicated with things like - when iron combines with oxygen it's called rust, when aluminum combines with oxygen it's called aluminum oxide. Aluminum is highly conductive to heat and electricity - BUT aluminum oxide is a very good insulator. (They use little aluminum plates as insulators between power semiconductors and cooling fins). Aluminum oxide forms faster than a match burns (wood combining with air). Because electricity would like to flow on the outside of the conductor and aluminum is very conductive it's happy flowing inside the wire, just below the layer of aluminum oxide on the outside of the wire (like insulation). So when wiring, you have to coat the wire with goop, scrape off the aluminum oxide and before it has time to oxidize, stick it in the terminal and tighten it down.
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legendsk
Member
Plus on the speed spectrum an RV fire can nearly be called an explosion. 10 minutes from a little smoke to the steel frame laying on the ground is pretty common.
Alright, the guy figured a loose connection. He's gonna run 6-2 copper in conduit, and hardware into the grizzl-e. We're most likely going to use the existing aluminum for a generator input into the house with an interlok. I already have that interlok on a lower gauge copper to the other end of my garage, but if I move the super-rarely used generator to this aluminum (plus it's on a much lower amperage) I wouldn't be concerned about it ever failing, and then that other 240 going to the other end of the garage I can set up as a second level 2 charger @ 24 amps in the future.
He said he has seen other 14-50 fail (with copper also) but normally it's just the outlet more than the big mess of crap that happened to me.
He said he has seen other 14-50 fail (with copper also) but normally it's just the outlet more than the big mess of crap that happened to me.
beatle
Active Member
No issues running a properly sized extension cord to charge. Cords come in all different lengths and gauges, so Tesla just opts out of trying to provide any guidance, lest someone melt their 100 ft 20awg 5-15 cord. I use a homemade 25ft 12awg cord with 6-20 ends on it to charge at a family member's house for over 20 hours straight, and I used an 8awg 14-50 extension cord to charge my Lightning for 6 weeks from the 14-50 in my garage.
That said, I don't think I'd make an extension cord part of a permanent installation plan, but there's nothing wrong with using them as they were intended.
Extension cords are not intended for EV charging. Using one is a fire hazard, even if it is convenient.
DeltaOne
Member
Back in July our neighborhood had a three hour electric outage. A few hours after the power had been restored I went out on an errand. I was quite surprised to see about a dozen homes on a cul de sac powered by what appeared to be a 500 foot extension cord.
The long extension cord even crossed my street! Where it ran across the street they had covered it with some of that safety stuff...kind of a mini speed bump. The extension cord ran from an in-ground transformer on my street to another in-ground transformer about 500 feet up the connecting street.
The long extension cord stayed in place for two days. I guess they were waiting for parts to come in.
beatle
Active Member
The instructions for the Mobile Connector state that it should not be used with an extension cord. It's even written on the back of the Mobile Connector. You may choose to ignore this because it limits what you want to do.
In addition to the wire gauge concern, if you use an extension cord, then there is no temperature monitoring of the outlet that the extension cord is plugged into. The Mobile connector has a temperature sensor embedded in the adapter plug to do this. The reason is to detect a faulty outlet connection and shut down the current before a fire starts. By using an extension cord, you defeat this safety provision.
If you use an extension cord, then there how would you detect a melting connector aside from using the home smoke detectors?
Sounds like you rate convenience above safety. Good luck to you.
beatle
Active Member
Tesla chooses to simply say "don't use one" as there are too many variables for them to consider in their approval, and since the NEC stops at the receptacle, they have no legal recourse. They have nothing to gain by evaluating extension cords. It's just lawyering. There are plenty of beefy extension cords sold specifically for EVSE and continuous RV use - some of which use more robust wiring than the circuit itself. The Gen1 UMC and many other portable EVSEs lack thermistors in their plugs.
Taking the time to research the specs of the cord as it relates to your use case requirements will let you use one safely, just like sizing the wiring for a circuit should be done. Saying all extension cords are okay is just like saying none are okay. It ignores the reality that cords are made for a purpose. They're neither enchanted nor cursed.
Taking the time to research the specs of the cord as it relates to your use case requirements will let you use one safely, just like sizing the wiring for a circuit should be done. Saying all extension cords are okay is just like saying none are okay. It ignores the reality that cords are made for a purpose. They're neither enchanted nor cursed.
How do you know why Tesla did this? Source, or it's just rationalizing risky behavior.
But then Tesla added temp sensors to the later UMC. Maybe there were too many house fires? Adding unnecessary parts is not the Elon "the best part is no part" Musk way.
TunaBug
Member
How would a GFCI breaker have helped your situation? GFCI isn't going to detect thermal issues at the outlet. Probably what saved your house is the temperature sensor in the mobile connector's plug which alerted the charger/car that there was a problem. That sensor is in the plug which is physically in contact with the receptacle.
I think GFCI breaker's are required per code for a 14-50 outlet, and that causes a whole different set of issues (which you can read about on this forum). IMO one of the advantages of hardwiring is that you do not need the GFCI breaker to meet code requirements.
I asked and he said in fact it would be an arc fault breaker but it's $300+ for a big boy one, and was overkill here, although he appreciates I may be gun-shy after what happened.
The wire to the 14-50 literally burned itself right out of the 14-50 outlet btw!
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