Charging cable overheats

[ahostmadsen]

it has been a while since it reduced charge to 16A as I use charge on solar, and it has not given me 32A consistently. But today it was a sunny day, and it dropped from 32A to 16A after some time.

I checked again, and the only thing that was hot were the prongs on the plug. So, that means probably the just installed outlet is bad, it cannot handle 32A. I need to complain to the electrician who installed it.

 

[ahostmadsen]

As you can see from the picture, the outlet is rated at 50A. So, it's not clear to me how I can complain to the electrician.

 

[Eric33432]

it has been a while since it reduced charge to 16A as I use charge on solar, and it has not given me 32A consistently. But today it was a sunny day, and it dropped from 32A to 16A after some time.

I checked again, and the only thing that was hot were the prongs on the plug. So, that means probably the just installed outlet is bad, it cannot handle 32A. I need to complain to the electrician who installed it.View attachment 1006936

Looks like you got a Leviton, which is inadequate for continuous duty EV charging. Replace it with a Hubbel 14-50

 

[MP3Mike]

As you can see from the picture, the outlet is rated at 50A. So, it's not clear to me how I can complain to the electrician.

The wires probably weren't tightened correctly. But even so that is a low quality outlet.

 

[cali8484]

As you can see from the picture, the outlet is rated at 50A.

Only if it's installed with wiring connections tightened properly.

 

[rwiegand]

How does an outlet get a UL approval for a 50A label if it can't handle a 32A load?

 

[ahostmadsen]

How does an outlet get a UL approval for a 50A label if it can't handle a 32A load?

I wonder about the same. Perhaps there testing procedures are not rigorous enough, have not been updated to EV times? They only test 50A for a moderate duration, not the consistent draw of EV charging?

 

[ahostmadsen]

Only if it's installed with wiring connections tightened properly.

The electrician seems competent, although leaning towards low cost solutions. I would believe he would find a cheap outlet. But if it's rated for 50A, who can blame him?

 

[Cosmacelf]

How does an outlet get a UL approval for a 50A label if it can't handle a 32A load?

Good question. We’ve been wondering that for a long time ourselves. Receptacles used for EV charging loads have been melting for the last ten years. The only good part about it is that other safety systems seem to be working as I don’t recall any house fires because of these incidents.

 

[E90alex]

1) it’s not designed for sustained max load for hours like what an EV demands. Other 240V equipment might spike high load for short periods but generally run much lower.

2) it’s not designed to have things repeated plugged and unplugged like you might do for an EV charger. Typically 240V equipment gets plugged in and never moved again. Plugging and unplugging wears down the contacts and causes arcing.

 

[MP3Mike]

The electrician seems competent,

But they could have easily made a mistake. You need to have it checked. Though I would still suggest replacing the outlet with a higher quality one.

 

[3sr+buyer]

View attachment 1006936

Your photo shows that the contacts to the plug blades in the outlet are half size (looks like a Leviton 279-S00). This means more resistance and heat generation at high amperages.

 

[3sr+buyer]

But they could have easily made a mistake. You need to have it checked. Though I would still suggest replacing the outlet with a higher quality one.

Replacing a Leviton 279-S00 receptacle (as the one in the photo appears to be) with a better one could run into the problem in that many other receptacles are physically larger and may not fit in the box (this could be one reason the Leviton 279-S00 is so common -- it has a compact design that fits in places other receptacles cannot fit in).

 

[3sr+buyer]

Only if it's installed with wiring connections tightened properly.

However, proper installation of the wire connections does nothing to reduce the increased resistance and heat generation from the half size contacts to the plug blades that is evident in the photo.

 

[cali8484]

However, proper installation of the wire connections does nothing to reduce the increased resistance and heat generation from the half size contacts to the plug blades that is evident in the photo.

I have charged on Leviton and other non-industrial but UL listed NEMA 14-50 outlets at 40A consistently over 5+ years without heat or current reduction issues. One key thing that could make a difference is how often you plug and unplug from the outlet. I rarely unplug.

 

[cali8484]

The electrician seems competent, although leaning towards low cost solutions. I would believe he would find a cheap outlet. But if it's rated for 50A, who can blame him?

I guess your electricians never make mistakes?

 

[Mull031496]

Agree with the general guidance here. The Leviton receptacle may meet the requirements for a UL listing @ 50 amps but it is not up to the task for charging an EV, which is one of the reasons why Tesla has issued specific guidance on what receptacles to use:

https://www.tesla.com/sites/default/files/downloads/en_CA/CA-EN%20NEMA%2014-50%20Installation%20Guide.pdf

There have been plenty of reports on this forum of lesser quality, UL listed, receptacles melting down.

 

[3sr+buyer]

There have been plenty of reports on this forum of lesser quality, UL listed, receptacles melting down.

Seems like most such reports are of Leviton receptacles with half size contacts to the plug blades.

 

[stopcrazypp]

How does an outlet get a UL approval for a 50A label if it can't handle a 32A load?

50A label is for an intermittent load, not a continuous load that runs for hours. NEC says to derate 80% for continuous, so theoretically, a 50A outlet can handle 40A continuously, although it may not be tested that way.

The problem is these types of outlets actually work for a quite a while with no problems (even the absolute worst Leviton outlet with half sized contacts as shown), but problems may show up months or years later. I doubt the UL test has such long term testing factored in.

 

[stopcrazypp]

it has been a while since it reduced charge to 16A as I use charge on solar, and it has not given me 32A consistently. But today it was a sunny day, and it dropped from 32A to 16A after some time.

I checked again, and the only thing that was hot were the prongs on the plug. So, that means probably the just installed outlet is bad, it cannot handle 32A. I need to complain to the electrician who installed it.View attachment 1006936

You can clearly see the contacts are half sized. And sure enough, it's the Leviton 14-50 outlet that people warned you about.
This is bar none the absolute worst 14-50 outlet you can install for EV charging:
Master Thread: Definitive 14-50 NEMA Outlet Guide
There are many cases of overheating when using that outlet, even to the point of melting it.

There are other $10 outlets that have full size contacts, so it's not even a price thing (Lowe's carries a Utilitech):
https://www.lowes.com/pd/Utilitech-Black-50-Amp-Round-Range-Industrial-Range/3775483

It's just that Home Depot carries the Leviton, so that's the first thing most contractors grab. I wish there was some warning label on that to say it's not for EV charging.

As per thread linked however, Tesla recommends an industrial outlet (most popular affordable model being the Bryant 9450FR for around $50, which I have myself), but the size is different (diameter of the circle is larger), so a different cover plate has to be used for it, and it's much thicker (so might not fit in some electrical boxes).