HPWC Fried

[mhunt]

Last night I tried to charge my Tesla and the HPWC was not responding. I checked the breaker and reset button and both seemed fine.

I turned off the power and opened the cover-which led me to this and a burning smell. The HPWC was purchased in October 2017 but I didn't get around to actually having the electrician install it until September 2018.

The cables and breaker used were to spec. The run is very short-the main electrical panel is literally on the other side of the garage wall where the HPWC is mounted.

I have a call into my electrician and Tesla. Tesla would like to send a mobile tech to diagnose it ($125) but I think they're just going to say it has to be replaced anyway.

 

[MP3Mike]

There was another case similar to this reported recently. It looks to me like the electrician either didn't properly torque the connection or there was some other issue with it. (Not inserted far enough, insulation left on wire, etc.)

The one strand sticking out from the L1 terminal seems really weird to me, I don't know if heat can cause a strand to break, it if maybe that strand was cut when stripping the wire. (Or maybe the wire was defective and had a break in it, but that seems highly unlikely.)

 

[Lloyd]

Looks like someone (your electrician) put a 2nd wire into the L1 terminal. This is not allowed and would have been not fused properly. He could have started a fire!!

 

[MP3Mike]

Looks like someone (your electrician) put a 2nd wire into the L1 terminal. This is not allowed and would have been not fused properly. He could have started a fire!!

You think it is a separate wire and not a strand coming off of the wire? (The second picture is too dark for me to try to see if it goes somewhere.)

 

[Lloyd]

Yes, looks to me like it melted the insulation of the main L1 from the outside.

 

[MP3Mike]

@mhunt Did the electrician happen to put in a standard 120v outlet in at the same time as the HPWC?

Is there chance of getting more pictures showing where the one wire/strand coming off the L1 terminal goes to?

 

[Rsdavis9]

I installed my own HPWC and I didn't like the way the wire clamps were the square box kind instead of round with a screw to clamp. I know the square box kind is used when you put the optional top entry box on so that the wires from the top mount box which have been terminated with the square lugs.

I suppose I should have taken my multi stranded #6 and attached the square lugs(what are they called?) but I just chose to put the wire directly into the square clamps. I torqued it a lot and tested the hold. In any case I prefer the round hole and screw clamp type. Also the positioning of the clamps was such that you couldn't see them without a dental mirror. Which I used to verify that all strands were engaged.

Long story short I bet the electrician didn't get the clamps tight enough or correctly engaging(clamping) the wire.

 

[bishoppeak]

I had a similar problem, although not so destructive. Bad main wire connections, solved by reducing 2 AWG wire diameter slightly and using insulated ferrules.

 

[murphyS90D]

The installation manual calls for copper ferrules on the ends of the wires. Were they installed? They provide a solid surface to clamp down on. Without them it is easy to get a high resistance connection because some strands may not be clamped.

 

[Silicon Desert]

Oh that is nasty. Just out of curiosity, how many times had you charged the car before this disaster?

 

[MP3Mike]

The installation manual calls for copper ferrules on the ends of the wires. Were they installed?

Well not exactly. It says "Strip the service wires going to the terminal block on the top entry bracket 3/4" (18 mm). Ferrules are recommended.".

So it says that they are recommended, not specifically calling for them.

 

[jeffro01]

The picture really looks like a second wire was added to L1 judging by the burn marks and insulation appearance. Where does it go? Why was it put there?

FWIW, I open mine up every 6 months and have a look at the connectors and check for torque just to be safe. I don't use ferrules but rarely charge at anything higher than 50amps even though I'm using #2 copper on a 100amp breaker. Every so often I'll need the 72, hence the maintenance checks done every 6 months. Better safe than sorry...

Jeff

 

[Silicon Desert]

FWIW, I open mine up every 6 months and have a look at the connectors and check for torque just to be safe.
Jeff

Hmmm, so why do you do that? Do you also check all the connections in your electrical panel? I'm confused

 

[BrokerDon]

How many amps were you charging at?

Our July 2015 installed HPWC is on a 100A breaker and set to 80A max charge rate but we only charge our 2015 P85D (dual 40A chargers) at 60A to minimize electrical issues with our Tesla HPWC plug and our P85D's charge port... both which run significantly hotter charging at 80A.

 

[jeffro01]

Hmmm, so why do you do that? Do you also check all the connections in your electrical panel? I'm confused

Yes, I check it all. I start with the breaker and look for signs of heat damage, then I turn off the breaker to check the torque on the screws. From there I work my way to a set of lugs I have that I had to use to for the run that I have to make sure there are no signs of heat damage on them. Then I open the HPWC and do a visual inspection followed by a torque check on the L1/L2/G screws.

Why? Because there are usually early warning signs with regards to heat related stress on electrical connectors and I'd rather my house not burn down because of it.

Jeff

EDIT: To be clear, no I don't check every breaker in the panel because I do not have another breaker even approaching 100amps.

 

[Silicon Desert]

Yes, I check it all. I start with the breaker and look for signs of heat damage, then I turn off the breaker to check the torque on the screws. From there I work my way to a set of lugs I have that I had to use to for the run that I have to make sure there are no signs of heat damage on them. Then I open the HPWC and do a visual inspection followed by a torque check on the L1/L2/G screws.

Why? Because there are usually early warning signs with regards to heat related stress on electrical connectors and I'd rather my house not burn down because of it.

Jeff

EDIT: To be clear, no I don't check every breaker in the panel because I do not have another breaker even approaching 100amps.

Thanks. Is your name Adrian Monk? Kidding of course. I guess it never hurts to check things out when you have spare time. Maybe I'm just over-confident that nothing like that is going to happen. Then again, electrical engineering is my main career, and no problems in 40 years of not checking. I check it when I buy a house and that's it. Wait a minute.... is that smoke I smell coming from the garage? I gotta run quick

 

[jeffro01]

Thanks. Is your name Adrian Monk? Kidding of course. I guess it never hurts to check things out when you have spare time. Maybe I'm just over-confident that nothing like that is going to happen. Then again, electrical engineering is my main career, and no problems in 40 years of not checking. I check it when I buy a house and that's it. Wait a minute.... is that smoke I smell coming from the garage? I gotta run quick

LOL While I'm not normally this diligent with all things in life, I do keep up on this one thing... Call it OCD... I've seen two garage electrical fires in my life due to YouTube electricians and while that's not my situation, the electrician that did my HPWC install to begin with wasn't exactly EVSE experienced.

I figure it takes me 15 minutes every 6 months to look and to date I've never had any torque issues or seen any visible signs of heat stress. I say that to say I was just thinking of going to yearly checks at this point since if it was going to come lose or whatever it would have done it by now.

Jeff

 

[MikeQ]

Our HPWC started tripping the breaker after about a year of installation. We charge a Model X and a Model 3. For some reason it started tripping on the Model 3 first but then started on the Model X soon after.

I found that the same hot terminal on that block was not tightened down enough. The red insulation had faded a bit right at the block. Ours was installed and inspected by professionals so I doubt it was loose from the beginning. I suspect thermal expansion and contraction is causing it to loosen over time.

 

[tls]

@mhunt Did the electrician happen to put in a standard 120v outlet in at the same time as the HPWC?

Yeah. That. Unless the picture is very misleading, my money says the helpful installer gave you a "15A" 120V convenience outlet conveniently fused at 100A...and its branch wiring overheated, since it was sized for 15A, and burned stuff up. If a licensed electrician did this, it's worth contacting the local AHJ - they will want to (and should) (re)inspect his other jobs before one of them catches fire in a more extensive way. Unless of course the local inspector went to high school with his dad or a hundred other kinds of ubiquitous badness.

Used to see this a lot in outdoor pool GFCI/timer boxes etc - then they started selling them with a couple extra spaces for convenience breakers and the problem (mostly) went away.

 

[whitex]

LOL While I'm not normally this diligent with all things in life, I do keep up on this one thing... Call it OCD...

At the risk of feeding your OCD, do you have a FLIR camera? Every now and then I walk around and check temperatures of things, checking for any unexpected hot or cold spots. I engage my HPWC at 80A to make sure nothing along the way (from breaker to car) heats more than than in the past. Just my geeky OCD, but FLIR saves me from having to take covers off to inspect (I have OCD combined with laziness ). Only once did I ever find something, a loose wire on one of my breakers (was heating up more than others, turned out it was not tightened properly), but like you, I don't mind checking from time to time.

I've seen two garage electrical fires in my life due to YouTube electricians and while that's not my situation, the electrician that did my HPWC install to begin with wasn't exactly EVSE experienced.

Hence I do most of my installs myself, then have the inspector sign off on things which need signing off. Of course I have the benefit of growing up in a family of electricians (or EE) spanning 4 generations. I fully realize that most of the things I do is overkill, but it helps me sleep better at night. As for work of "real electricians", I found a couple of "easter eggs" the builder's electrician had left behind - the problem is of course that an inspector is not going to trace each wire run to verify that the electrician didn't do something stupid to cut corners. *sigh*