Burnt wire in the wall charger

[dilsherd]

Background : I installed the rivian wall charger back in October 2023. All worked fine - pulling 48A and had the electrician install a 70A circuit. A few weeks back - I noticed that an hour or so after plugging in - the wall charger would go red and the car would stop charging. The app would say "vehicle error".

I would reset the breaker - plug it back and the same thing would happen. I opened a service ticket and meanwhile, I reduced the amps to pull to 44A. Everything worked great (overnight charging and never went red).

A few weeks back I got a F150 lightning and plugged it in. Now the F150 doesn't have the option to reduce the amps - so it's going to pull whatever the charger can (until 80A I think). Same thing - the charger went red after a while.

At this point I figured I'll open the charger and change the switches such that they pull only 40A (there's a nice schema in the charger to do that). That's when I noticed that there's a burnt wire.


My electrician says he'll have to replace the wire and charging $250 - meanwhile I'm now in contact with the home charging team. I'm trying to figure out - is this something the electrician messed up or is the charger messed up?

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[opnwide]

Tell us more about what the large black wire run from the breaker box to charger installed is…gauge, Romex/NM-B, THHN? Is there any printing on the sheath? Just a starting point-may/may not be the issue. (Looks like some nice victim fly fishing bugs I could use as well).

 

[Nuclianba]

I would wager this is the electrician's fault. The install looks super lazy. First of all, that wire between your panel and the charger should be in conduit (so should your 20A yellow romex to the outlet below the charger, but I digress). Those wires just running exposed would never pass inspection in my neck of the woods....electrical code requires wires to be protected from physical damage, and every inspector I've worked with basically requires anything in an exposed wall cavity (like you have in your garage) to be shielded or in conduit. Stuff up in the ceilings/rafters are generally ok without it.

Next, your wire just passes through the hole in the charger back, no clamp connector is present (something like this should be there: https://www.homedepot.com/p/Halex-1-in-Non-Metallic-NM-Twin-Screw-Clamp-Connector-90513/100113541). I would wager he also didn't put one on the panel either...this is a big no-no. The clamp provides strain relief and protects the connections (lets say you accidentally hit the cable one day while walking by with a suitcase or something...that is going to tug on the connector in the wall charger since nothing else is holding that wire in place anywhere. You NEED a clamp to ensure that tugs on the wire etc dont pull on the connectors in the charger OR in your panel).

It looks like your hot wire had a loose connection at the charger, and that led to high resistance at that point, and things got hot and melty. You can see that the screw terminal on your charger wire block for the hot wire is black, the green plastic around it is melty, and the circuit board below it looks black and burned. And the wire got hot and the sheathing got fried too. Frankly, your electrician saying it just needs a new wire is crazy...get a new electrician. The connector on your charger is fried, no electrician should be OK hooking up a new wire to a fried connector and thinking that is safe (and if he's just going to repeat his prior install without conduit or clamps, you're asking for more issues).

And FINALLY: He ran like 6 feet of cable. 6/3 cable (I assume that is what he ran based on your description) is $5 a foot from a big box store...he should be getting it at half that price or lower as an electrician (because he's buying in much larger quantities). Without conduit and clamps etc, that whole job is basically a 5 minute install. Not a great deal for $250.

 

[DucRider]

It looks like it was improperly torqued (too little or too much) and it developed into a poor connection causing excess heat. Over time, excess heat degrades the connection further generating even more heat. The end result is what you see.

While there are other possibilities, that is the most likely cause.

It looks like the terminal may also have been damaged. Component level repair is rarely done and you may need a replacement Wall Charger.

Edit: @Nuclianba pointed out the numerous other install issues.

 

[WSea]

EVSE should have never charged over 40amp with 6/3 romex. Get an electrician who knows what he’s doing. Assuming no permit was pulled

 

[Polar]

In no way is this the EVSEs fault; do not pass go, do not call Rivian.

 

[VSG]

What @Nuclianba and @DucRider and @WSea all said is correct.

Your charger needs to be replaced. The melted terminal block cannot be fixed, and there is likely damage to the internal power layer of the PCB and possibly to other components.

Your wiring needs to be replaced with the correct size and type. Likewise couplings need to be added and probably conduit unless you want to seal up that wall.

And a 70A breaker? What's that all about? It should be 60A max and then only if you have the correct wiring.

The failure is almost certainly because the screw terminal wasn't torqued enough, creating excess resistance/heating. This was exacerbated by the undersized wires and the oversized breaker.

If you had an electrician do this work, then you need a new electrician. IMO your original electrician should pay for the damage. You're lucky you didn't have a fire.

 

[240vPlug]

What size wire is that? Also, 70amp is not the correct breaker. That should be on a 60 amp breaker.

If your wire is inside conduit you can use #6 THHN or MC. Romex needs to be up sized to be code complaint so #4 wire. Using #6 Romex sometimes happens though but it's max ampacity is 55 amps.

The typical install is either for 48 amps on a 60 amp breaker or 40 amps on a 50 amp breaker.

The wire looks really small but it's hard to tell from the pics.

What others have said also appears to be correct. The electrician needs to replace the charger and redo the job. This time I would recommend you have it permitted and inspected. That gets a second set of eyes on the job and keeps the electrician honest.

 

[SilverII]

I agree with the poster above.

Also, I got paranoid and opened my wall charger and everything looks new/unburnt. Whew````

 

[Zoidz]

Your electrician is sloppy and does not know, or does not care, about codes and standards. As you can see, the result can be hazardous. It's hard to tell from the photo what type of wire was actually used. Since he used a 70A breaker, he might have used #6 THHN which is rated at 75 Amps and thought it was OK to install this way.

When an electrician is sloppy on following the physical standards, questioning their attention to the electrical standards is a bigger concern. Find another electrician and get it done right.

 

[Zoidz]

...

What others have said also appears to be correct. The electrician needs to replace the charger and redo the job. This time I would recommend you have it permitted and inspected. That gets a second set of eyes on the job and keeps the electrician honest.

I would not let this knucklehead electrician back in my house. If he worked for my company and did this, he'd be looking for a new job.

 

[HaveBlue]

I don't think changing the switches inside will reduce the maximum current without a reset from Rivian. I think those chargers are weird that way. Not that it matters because looks like the unit may be toast. Stranded wire is tricky to get tightened correctly and the install failed. It got loose and here is the result. I suggest you have all your main panel breaker leads, neutrals and grounds checked. I would also check the breakers and bus bar for overheating damage. You indicated that you installed the charger. Bringing in a licensed electrician would be the way to go to get it fixed.

 

[SparkyR1t]

I don't think changing the switches inside will reduce the maximum current without a reset from Rivian. I think those chargers are weird that way. Not that it matters because looks like the unit may be toast. Stranded wire is tricky to get tightened correctly and the install failed. It got loose and here is the result. I suggest you have all your main panel breaker leads, neutrals and grounds checked. I would also check the breakers and bus bar for overheating damage. You indicated that you installed the charger. Bringing in a licensed electrician would be the way to go to get it fixed.

Correct the new gen 3 wall connectors by Tesla broadcast a SSID and when you connect to them with your smart phone or tablet you are given the option to set your breaker size which sets max current. They also record faults and will display date and time and description of the fault. Also don’t forget high current wiring like that found in a wall connector should be inspected at least once a year visually (after turning off power and verifying de-energized) and wiring terminals should be checked and retorqued if needed using an inch pound torque wrench.

 

[R1Thor]

I would not let this knucklehead electrician back in my house. If he worked for my company and did this, he'd be looking for a new job.

I agree with you, but it's a double edged sword.

He should be held liable for and correct his mistakes, which includes procuring OP a new EVSE from Rivian, since his installation caused the damage.

I'd probably get an electrician *who knows what he/she is doing* write up a report, with an estimate to have it repaired, and then submit that invoice back to the original electrician for reimbursement to have it done properly.

If he refuses, then lawyer up. This could've caused an electrical fire that could've turned out much...much worse.

 

[stewart]

I would wager this is the electrician's fault. The install looks super lazy. First of all, that wire between your panel and the charger should be in conduit (so should your 20A yellow romex to the outlet below the charger, but I digress). Those wires just running exposed would never pass inspection in my neck of the woods....electrical code requires wires to be protected from physical damage, and every inspector I've worked with basically requires anything in an exposed wall cavity (like you have in your garage) to be shielded or in conduit. Stuff up in the ceilings/rafters are generally ok without it.

Next, your wire just passes through the hole in the charger back, no clamp connector is present (something like this should be there: https://www.homedepot.com/p/Halex-1-in-Non-Metallic-NM-Twin-Screw-Clamp-Connector-90513/100113541). I would wager he also didn't put one on the panel either...this is a big no-no. The clamp provides strain relief and protects the connections (lets say you accidentally hit the cable one day while walking by with a suitcase or something...that is going to tug on the connector in the wall charger since nothing else is holding that wire in place anywhere. You NEED a clamp to ensure that tugs on the wire etc dont pull on the connectors in the charger OR in your panel).

It looks like your hot wire had a loose connection at the charger, and that led to high resistance at that point, and things got hot and melty. You can see that the screw terminal on your charger wire block for the hot wire is black, the green plastic around it is melty, and the circuit board below it looks black and burned. And the wire got hot and the sheathing got fried too. Frankly, your electrician saying it just needs a new wire is crazy...get a new electrician. The connector on your charger is fried, no electrician should be OK hooking up a new wire to a fried connector and thinking that is safe (and if he's just going to repeat his prior install without conduit or clamps, you're asking for more issues).

And FINALLY: He ran like 6 feet of cable. 6/3 cable (I assume that is what he ran based on your description) is $5 a foot from a big box store...he should be getting it at half that price or lower as an electrician (because he's buying in much larger quantities). Without conduit and clamps etc, that whole job is basically a 5 minute install. Not a great deal for $250.

Great response. Complete. I agree with all of it. The burning appears to me to be the result of a loose connection on the hot (black) wire. That will cause arching and heating. Evidence of both in the picture.

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