Tesla to Upgrade Wall Adapters After Reports of Garage Fires - Bloomberg News

[swaltner]

What would be nice would be an additional replaceable thermal sensor (the kind that changes colours) so that you could tell what the hottest temperature was. That would give you some early warning before things actually got to the tripping stage. House wiring doesn't go from "perfect" to "failed" overnight, it degrades over time.

The thermal sensor needs to be replaceable so that an over-temperature colour change doesn't impact future use. That is the colour change needs to be permanent, and then you replace the heat sensitive material once the wiring problem is rectified.

You're wanting a Telatemp Irreversible Temperature Label. Robinson Helicopter puts these on bearings all over their helicopters for just the reason you're talking about. Warn of impending failure and they are cheap to replace and very easy to check before every flight. They are less than $2 each, although direct from telatemp they have a minimum order size of 20.

Irreversible Temperature Tags and Labels | Telatemp

As to which temperature ranges would be best to use for this application, I don't know...

 

[vgrinshpun]

You're wanting a Telatemp Irreversible Temperature Label. Robinson Helicopter puts these on bearings all over their helicopters for just the reason you're talking about. Warn of impending failure and they are cheap to replace and very easy to check before every flight. They are less than $2 each, although direct from telatemp they have a minimum order size of 20.

Irreversible Temperature Tags and Labels | Telatemp

As to which temperature ranges would be best to use for this application, I don't know...

Per NEC the default (unless stamped otherwise) temperature rating of the terminations used in circuits less than 100A is 60 Deg C (140 Deg F). The temperature of the surface of the Nema 14-50 wall outlet or an adapter will be lower, but the 60 Deg C should be a good starting point for the warning. I would go with 110-2 (60 DegC to 88 Deg C).

 

[Lou Olsen]

Just for the record, I've had my MS for almost a year now and have charged it nearly 300 times at home using the standard adapter with absolutely no issues. Not even warm to the touch.

 

[stevezzzz]

Just for the record, I've had my MS for almost a year now and have charged it nearly 300 times at home using the standard adapter with absolutely no issues. Not even warm to the touch.

Similar experience for me. I took delivery at the end of September 2012, and charge with the UMC and a NEMA 14-50 every night for the last 15 months. My Service Center called me once in the first few months to see if I was having any overheating problems with the adapter at the wall (I wasn't). Mine is barely above ambient temperature to the touch.

 

[Doug_G]

Just for the record, I've had my MS for almost a year now and have charged it nearly 300 times at home using the standard adapter with absolutely no issues. Not even warm to the touch.

I can report the same. I've been charging daily on my UMC for over a year and no issues.

 

[AlMc]

I can report the same. I've been charging daily on my UMC for over a year and no issues.

Same here. I have 14-50 installed at home and work so two different circuits and two different charging cords...no issues.

 

[vgrinshpun]

Ditto here. My adapter is warm to touch when in operation, but is not overheating and does not show any signs of degradation due to heat exposure neither on the outlet nor the UMC side. I have put about 11,000 miles in a little less than 6 month and am charging daily in my garage using the NEMA 14-50 outlet and UMC.

For the record, I worked with my electrician to make sure that he installed #6 AWG wires between the panelboard and the outlet.

 

[Dave EV]

Mine's been charging for a little over an hour at 40A on a 14-50. It's measuring 46ºC (115ºF) on the top of the adapter. A little lower on the UMC. Ambient temp 20º (68ºF).

~26C/50F rise over ambient is borderline unsafe. Typically safe limits are defined as 30C/54F rise. I suspect you have a high resistance connection in there somewhere.

 

[Cottonwood]

There are two other potential problems that can contribute to the overheating.

First is related to the gauge of wire installed between the panelboard breaker and the wall NEMA 14-50 outlet. According to National Electric Code (NEC) it is supposed to be #6AWG for 50A circuit, but electricians are routinely confused and install #8 AWG (American Wire Gauge). For a given current #8 AWG will run hotter than #6 AWG, contributing to overall heat build-up, particularly in the outlet-adapter.

The second is that NEC Tables used for sizing of all current carrying conductors are based on ambient temperature of 30 Deg C (86 Deg F). The typical installation in the garage, however, will see higher temperatures during the summer. This will require further derating of the current carrying conductors between the panelboard and the wall NEMA 14-50 outlet.

My reading of the NEC says that for 75˚C and 90˚C rated insulations, #8 copper wire is approved for a 50 Amp circuit. See Table 310.15(B)(16) from the 2014 NEC below. On the other hand, I agree with you; for lower Voltage drops and more thermal margin, when I have had 50 Amp circuits installed, I have requested #6 wire be used.

Also, you can see that #3 copper wire is sufficient for a 100 Amp circuit; I have installed two HPWC's, and two CS-90's; in each location, I have requested the use of #2 copper because it is often cheaper and more available than the less common #3, but more importantly, because it provides extra margin for the install.

BTW, Table 310.15(B)(2)(a) does provide derating factors for ambient temperatures other than 30˚C, 86˚F, and for a 40˚C, 104˚F, garage and for the most common 75˚C insulation, #6 copper would be required.

 

[lloyds]

Had my car since early last year and now I'm onto 13k miles. I supercharge once every week and about 4 times @ home. No problems so far and only slightly warm to the touch when I am unplugging.

 

[xhawk101]

Late is better than never. Much of the article is partly a snow job. It is a reactive response rather than a proactive response as they claim. It would have been proactive to have suitable hardware and protective software in the initial design.

I disagree with the claim the software update fully addresses the problem. Allegedly there still is overheating issues. The software update is a Band-Aid. The hardware issues are the underlining problems.


I'm sure there is bad wiring out there, however most, if not all of the Tesla overheated wires, adapters and connectors that I have seen, Tesla hardware seems to be at fault.

Even if an outlet fails, it doesn't necessarily mean that outlet is at fault. The way Tesla charger connections are typically configured, puts more stress on an outlet. That's one of the reasons why fire departments and engineers typically frown on devices similar to Tesla's adapter. The increased force can fracture socket insulators and can unspring receptacle connector prongs.

Also the way Tesla configures its connections, it concentrates the heat by locating several connections in close proximity. So the connectors and wall outlet is more likely to overheat. That's another one of the reasons why fire departments and engineers typically frown on such configurations.


Tesla also falsly indicated it got a 5.4 star safety rating in other press releases. Tesla & Elon Musk have creditability issues.

What press release? Are you misrepresenting the press release? You changing "can" into "it was"?

I'm sure there is bad wiring out there, however most, if not all of the Tesla overheated wires, adapters and connectors that I have seen, Tesla hardware seems to be at fault.

Rainbow you are totally off base and biased here suggesting "Elon has credibility issues".

You are the one with credibility issues.

 

[FlasherZ]

First is related to the gauge of wire installed between the panelboard breaker and the wall NEMA 14-50 outlet. According to National Electric Code (NEC) it is supposed to be #6AWG for 50A circuit, but electricians are routinely confused and install #8 AWG (American Wire Gauge). For a given current #8 AWG will run hotter than #6 AWG, contributing to overall heat build-up, particularly in the outlet-adapter.

This is incorrect. #8 AWG is good to 50 amps when used at 75 degree rating. If you use type NM cable, which requires you use the 60 degree column, you are correct in that #6 is needed. However, #8 AWG in conduit is just fine for 50A feeding a 14-50 outlet. (NEC table 310.15(B)(16))

The second is that NEC Tables used for sizing of all current carrying conductors are based on ambient temperature of 30 Deg C (86 Deg F). The typical installation in the garage, however, will see higher temperatures during the summer. This will require further derating of the current carrying conductors between the panelboard and the wall NEMA 14-50 outlet.

It is very rare that you need to do derating and an AHJ will hardly ever require you to do so, unless you're running in an attic. I have never seen an in-wall or garage installation require derating. Even if it did require de-rating, the factor is going to be .91 (NEC 310.15(B)(2)(a), ambient 40 deg rating), which would still easily allow for a #6. However, I've never seen an AHJ require that.

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BTW, Table 310.15(B)(2)(a) does provide derating factors for ambient temperatures other than 30˚C, 86˚F, and for a 40˚C, 104˚F, garage and for the most common 75˚C insulation, #6 copper would be required.

As mentioned, this is typically required in attic or other high-temperature special cases only. In-wall or garage will not require derating under normal conditions unless your AHJ is a complete idiot -- in which case, you should escalate to his supervisor or file an emergency appeal to the supervisory board. This will usually cause him/her to rethink his position and learn the code.

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I've been gone for a little bit dealing with various things, but I'm back to read through things. I have had the same experience as mentioned earlier with my HPWC (the car's coupling connector was extremely hot - over 120 deg F). Tesla came out and replaced the cord set from the HPWC to the car and it cleared things up; I was told that if that didn't fix it, they would replace the connector on the car.

 

[vgrinshpun]

My reading of the NEC says that for 75˚C and 90˚C rated insulations, #8 copper wire is approved for a 50 Amp circuit. See Table 310.15(B)(16) from the 2014 NEC below. On the other hand, I agree with you; for lower Voltage drops and more thermal margin, when I have had 50 Amp circuits installed, I have requested #6 wire be used.

Also, you can see that #3 copper wire is sufficient for a 100 Amp circuit; I have installed two HPWC's, and two CS-90's; in each location, I have requested the use of #2 copper because it is often cheaper and more available than the less common #3, but more importantly, because it provides extra margin for the install.

View attachment 40495

BTW, Table 310.15(B)(2)(a) does provide derating factors for ambient temperatures other than 30˚C, 86˚F, and for a 40˚C, 104˚F, garage and for the most common 75˚C insulation, #6 copper would be required.

According to the NEC the conductors need to be selected not only based on temperature rating of the conductor INSULATION but also based on the temperature rating of the TERMINATIONS. Refer to NEC Section 110.14 (C)(1) Electrical Connections-Temperature Limitations-Equipment Provisions. This section essentially states that regardless the temperature rating of the insulation, the conductors must be sized based on the temperature ratings of the terminations. The default rating of the terminations for 600V and below circuits less than 100A is 60˚C. So unless all of the terminations of all of the components of the circuit (panelboard breaker, Nema 14-50 wall outlet, Tesla plug adapter, tesla plug on UMC adapter side) have terminations rated higher then 60˚C, the proper conductor sizing must be based on 60˚C column of the table 310.15(B)(16) as appropriately modified by 310.15(B)(7).

The problem is that a lot of electricians as well as electircal engineers are confused with this requirement and size conductors improperly. I participated in writing Cable Size Selection Guide for a major corporation which design and build power plants, and experienced this confusion among many engineers I delt with first hand.

The subject is addtionally clouded by the fact that majority of the low voltage breakers rated less than 100A are nowadays have terminations rated 75˚C. Based on this a lot of people jump the gun and size conductors based on 75˚C, forgetting that other components of the circuit may be rated 60˚C, and in fact, according to the NEC must be assumed to be rated at 60˚C unless listed and marked otherwise. The most common NEMA 14-50 outlet, Leviton 279-C00 linked below has rating of 60˚C (30˚C temperature rise over 30˚C ambient)

http://www.leviton.com/OA_HTML/ProductDetail.jsp?partnumber=279-C00&section=42418&minisite=10251

I am willing to bet that majority of the overheating adapters are linked with the wiring installation using undersized conductors. This could be further exacerbated by the improperly tightened connections, improperly seated Tesla adapter, etc.


Tesla is doing the right thing providing redundant ways (software + replacing the adapters) to fix the potential problems with the equipment installation which has nothing to do with their design, because explaining these intricacies to a wider audience is a loosing battle.

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This is incorrect. #8 AWG is good to 50 amps when used at 75 degree rating. If you use type NM cable, which requires you use the 60 degree column, you are correct in that #6 is needed. However, #8 AWG in conduit is just fine for 50A feeding a 14-50 outlet. (NEC table 310.15(B)(16))

Sorry, Flasher, you are wrong on this one, see my post #93. The proper minimum size of the conductors to use for 14-50 outlet, regardles of the rating of insulation is #6AWG. It must be based on the lowest temperature rating of the TERMINATIONS, which is commonly 60˚C for NEMA 14-50 outlet.

This demonstrates the problem with confusion about the proper sizing of the conductors based on temperature rating of the terminations. I have read quite a few of your posts which are excellent, but you unfortunately just wrong on this one. Given my experience with fellow engineers and electricians, I am surprised that adapter overheating is not a more common that it seems to be.

 

[FlasherZ]

According to the NEC the conductors need to be selected not only based on temperature rating of the conductor INSULATION but also based on the temperature rating of the TERMINATIONS.

Yes, and most equipment built after the 1980's has 75 degree termination rating. Certainly all new stuff does.

The subject is addtionally clouded by the fact that majority of the low voltage breakers rated less than 100A are nowadays have terminations rated 75˚C. Based on this a lot of people jump the gun and size conductors based on 75˚C, forgetting that other components of the circuit may be rated 60˚C, and in fact, according to the NEC must be assumed to be rated at 60˚C unless listed and marked otherwise. The most common NEMA 14-50 outlet, Leviton 279-C00 linked below has rating of 60˚C (30˚C temperature rise over 30˚C ambient)

My home was built in 1991 and not a single device in the whole house is listed at less than 75 degree termination.

The specs you quote are incorrect and completely out of context. The listing sheet says that the max temperature rise is 30 deg C max after 50 cycles of outlet at 150% rated current. That does not refer to the termination temperature, but rather to the outlet's quality after a failure.

I just happen to have a 279-C00 in my garage and here's what it looks like... note the 75 deg C termination. (Also, just so you don't take exception to the statement, on the right side, just below this warning - and quite out of focus - is the notice that this device has a 75 deg C termination.)

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Sorry, Flasher, you are wrong on this one, see my post #93. The proper minimum size of the conductors to use for 14-50 outlet, regardles of the rating of insulation is #6AWG. It must be based on the lowest temperature rating of the TERMINATIONS, which is commonly 60˚C for NEMA 14-50 outlet.

This demonstrates the problem with confusion about the proper sizing of the conductors based on temperature rating of the terminations. I have read quite a few of your posts which are excellent, but you unfortunately just wrong on this one. Given my experience with fellow engineers and electricians, I am surprised that adapter overheating is not a more common that it seems to be.

I beg to differ; in this one you are incorrect, quite incorrect. Years of experience with residential and commercial wiring, and inspections performed by many competent inspectors prove that. If I am so incorrect, then why have tens of inspectors cleared all this wiring done by so many electricians and engineers?

#8 AWG is fine when THHN/THWN is used in conduit with 75 degree breakers and 75 degree outlets, which are all commonly used today. When you use NM cable, you must use #6.

As I demonstrated to you on the 279-C00, the termination temperature of almost every new device made is 75 deg C.

I do know what I am talking about. I hate to say this so strongly, but please stop giving incorrect information.

 

[Fedderman]

I appreciate the one pic of the new adapter.

I am, however, puzzled by some of the recent discussion here regarding the outlet-blade side of the new adapter. Just about all of the reports of overheating/failure I've seen with the UMC have been on the OTHER side of the adapter where it mates with the UMC cable head. I am assuming that side is what has been redesigned... either the phsical seating/locking configuration, or the electrical interface itself. Or perhaps both.

Any chance we can get a pic of that side of the new adapter?

Thanks.

Attached as requested. I believe you are correct that this is the side where the majority of the adapter issues have been - this is where my heat problem was, damaging both the adapter and the UMC where it plugs in. The new design seems to prevent bending the retention clip if the button is depressed when inserting the adapter.

 

[FlasherZ]

Compare the insulation near the prongs. Notice how the insulation around the prong in the nine o'clock position has good color and is well formed. Notice how the insulation around the prongs at the three clock and six o'clock position is discolored and malformed. It looks like it may have overheated and started to melt; though there are many other possible explanations.

It looked like standard manufacturing molding to me, but that's just my opinion. New molded appliance plugs look like that too - dryer cords, for example.

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Here's a pic of the new 14-50 adapter, with the "green dot" referred to above:

That's the same adapter I have had for about 8 months or so - same part #, same revision. I'm not sure that's the "new" adapter.

 

[Fedderman]

Look closer, more carefully, think deeper, more abstractly and learn.

It could have possibly been overheated or chemically burned during manufacturing.

Compare the insulation near the prongs. Notice how the insulation around the prong in the nine o'clock position has good color and is well formed. Notice how the insulation around the prongs at the three clock and six o'clock position is discolored and malformed. It looks like it may have overheated and started to melt; though there are many other possible explanations.

The somewhat iridescent blue and dull brown areas are often signs of overheating and oxidation. It could be a sign that the insulator is losing its insulating properties and becoming a conductor. I've seen it before and it can be very dangerous.

You seem to be looking for something that is simply not there. The photo shows some reflections of color which simply are not on the adapter. I have it in my hands, so believe me when I tell you it is "pristine".

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It looked like standard manufacturing molding to me, but that's just my opinion. New molded appliance plugs look like that too - dryer cords, for example.

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That's the same adapter I have had for about 8 months or so - same part #, same revision. I'm not sure that's the "new" adapter.

It may not be. It is the one my local SC (Palo Alto) gave me two weeks ago when I brought in my original (damaged) adapter & UMC. It has the green dot referred to by someone in an earlier post.

 

[FlasherZ]

It may not be. It is the one my local SC (Palo Alto) gave me two weeks ago when I brought in my original (damaged) adapter & UMC. It has the green dot referred to by someone in an earlier post.

Certainly, anything is possible, but from my experience, Tesla tends to update part numbers and revisions pretty religiously in MCO's. Perhaps the green dot represents a different manufacturer or tighter tolerances, but the design is likely to be the same. Either way, it seems that adapters that are replaced tend to work better, at least for a while. You might get another one in the mail soon.

 

[Electricfan]

No way should you have to use an oven mitt. Either the house wiring is defective in some way or the charge cord is. I hope you get this sorted before there's a fire.

 

[Lyon]

Will the thermal fuse be something that is resetable? What if it trips/burns out while you're on a road trip?

Unless they insist on taking the old one back just throw it in as a back-up.