Frightening Crackling/Zappy Sound Coming From NEMA 14-50 Charger

[Carl_P]

Hi everyone,

NEMA 14-50 outlet
Model 3 standard charger
Sits on 50 amp breaker on a copper line

Went out into my garage this morning to drive Model 3... didn't hear anything out of the ordinary. Car was plugged in.

Opened my car door. A/C in the car turned on basically to full blast (it's been hot). After a few seconds, I immediately hear a crackling, zapping type sound coming from the plug in the wall. I took a video but this site won't let me upload it. It sounded like electrical crackling

I listened for a bit to see if it would go away, but then decided after a minute that this was bad, and went down into the basement to shut off the breaker.

Any theories? Is the car pulling too much energy with the HVAC at full blast? Is the 50 amp breaker not working? Something worse?

Thanks,
CP

 

[Frank99]

Call an electrician.

If the noise was occurring from the wall plug, the most likely cause is that one of the wires to the plug has loosened. What you heard was electrical arcs as current jumped between (probably) the wire and the back of the outlet. An electrician will be able to diagnose where the problem occurred, and what needs to be replaced - expect to need a new outlet. When there is arcing like you heard, there is a tremendous amount of heating even though there may not be enough current flow to trip the breaker. You'll probably find that some plastic portions (and maybe some metal ones also) have melted. That's why new housing requires an "Arc fault Circuit Interrupter (AFCI)" on outlets in bedrooms and other locations - if there's arcing, there's a very high chance of fire and the AFCI will trip when a standard circuit breaker won't.

Make sure the electrician uses a quality outlet - Tesla recommends as an example a Hubbell part # HBL9450A or Cooper part #5754N. These will cost on the order of $100, which is vastly more expensive than the $10 Leviton you can buy at Home Depot, but this is probably one of those places where you get what you pay for.

 

[Vines]

Absolutely agree, do not use this outlet until you have an electrician look at it, or take it apart yourself if you are competent.

You did the right thing in turning off the breaker immediately.

 

[roblab]

Welllllll, again, I bought one of those cheap outlets, and they work as well as the expensive ones for me. I wired one in my garage over ten years ago, through a Toyota RAV4EV and three Model Ss and a 3. Still works great. Since it hardly ever gets unplugged there is barely any wear.

If you hear crackling, why not (with the breaker turned off) pull the outlet and look at the wires? Check for a loose screw holding the wire in, look for burned insulation. Nine times out of ten you can fix it yourself in minutes and leave the expensive electrician tending to more important things.

Of course there are people who do not understand wiring in any form who will get worried about things, but I prefer to look and learn and save my money to buy another Tesla. Just helped my daughter get a used 3 this week.

 

[Frank99]

roblab -
The cheap outlets are certified and expected to be safe. There is no doubt about that. The Hubbell is also vastly overpriced considering that the factory cost for building one is, let's say, $1 more than the Leviton outlet. That's a lot of profit margin.

In an EV charging role (especially one where the EVSE is plugged in and left alone), the cheap outlets should work fine. However, the assumption is that they're installed CORRECTLY - did you break out the inch-pound torque wrench and correctly tighten the clamp screws? Perhaps you didn't; if your calibrated elbow happened to do a good job, the installation should work fine just like it did when it was certified (where they certainly did torque the screws to spec). One area that an expensive outlet is better than a cheap one is those clamp screws; the better outlet has a more solid, more robust, more secure clamp than the cheap one. Over- or under-tighten the clamp on the cheap one, and you're far more likely to end up with a bad connection creating heat, melting plastic, and starting fires.

Yes, I consider myself knowledgeable enough to use and install a cheap outlet (though my UMC is plugged into a Hubbell), but IMHO installing a cheap outlet safely requires more knowledge and skill than installing an expensive one. The OP didn't sound like they had that knowledge and skill, and I don't have a really high opinion of the average electrician (hence my listing of the Tesla recommended outlets) so was suggesting the approach most likely to keep him from needing to become closely acquainted with his insurance agent.

 

[mrau]

Another good choice for a heavy duty 14-50 plug is the Bryant. It is very similar to the Hubbell but cost less at about $40. If you do decide to get a Hubbell or the Bryant, you have to get the Hubbell cover since the hole size in the Leviton cover is a bit too small.

Zoro is one place to get these. Shipping is $5 (free if a $75 + order).

Zoro Select Receptacle, 50 A Amps, 125/250V AC, Flush Mount, Single Outlet, 14-50R, Black 9450FR | Zoro

Order Zoro Select Receptacle, 50 A Amps, 125/250V AC, Flush Mount, Single Outlet, 14-50R, Black, 9450FR at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.

www.zoro.com

Hubbell Receptacle Wall Plate, 1 Circular Opening, 2.48 in Dia, 2 Gangs, Stainless Steel, Brushed, Silver SS701 | Zoro

Order Hubbell Receptacle Wall Plate, 1 Circular Opening, 2.48 in Dia, 2 Gangs, Stainless Steel, Brushed, Silver, SS701 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.

www.zoro.com

 

[Carl_P]

Call an electrician.

If the noise was occurring from the wall plug, the most likely cause is that one of the wires to the plug has loosened. What you heard was electrical arcs as current jumped between (probably) the wire and the back of the outlet. An electrician will be able to diagnose where the problem occurred, and what needs to be replaced - expect to need a new outlet. When there is arcing like you heard, there is a tremendous amount of heating even though there may not be enough current flow to trip the breaker. You'll probably find that some plastic portions (and maybe some metal ones also) have melted. That's why new housing requires an "Arc fault Circuit Interrupter (AFCI)" on outlets in bedrooms and other locations - if there's arcing, there's a very high chance of fire and the AFCI will trip when a standard circuit breaker won't.

Make sure the electrician uses a quality outlet - Tesla recommends as an example a Hubbell part # HBL9450A or Cooper part #5754N. These will cost on the order of $100, which is vastly more expensive than the $10 Leviton you can buy at Home Depot, but this is probably one of those places where you get what you pay for.

Thank you for the thoughts. Wanted to give an update on this:

I had an electrician come (the same guy that installed it). When he opened up the outlet, it was clear there was some melting of wire that had happened (you were right), as well as some burn marks on the outlet itself. However, he noted that the connection at the socket was NOT loose. He still replaced the entire outlet.

HOWEVER, after replacement of the outlet, while the charger was no longer making that crackling sound, the charging cable and EVSE were still heating up pretty good while charging. We measured temperature with a heat gun and the point of EVSE connection to the 14-50 plug head was measuring 110 degrees after charging for a bit. Also, the charging cord itself was getting somewhat hot. I am thinking there's something loose in the cable or plug now.

He didn't like this, and thought I should contact Tesla. So I am, and I have service coming tomorrow.

Do you think I need a new charging cable and EVSE, a new 14-50 plug head, or both?

 

[Frank99]

The Tesla mobile connector measures the temperature of the plug at the outlet; so if things get too toasty it’ll shut down or reduce power.
My mobile connector plug gets warm when charging. Without measuring it, I’d say it’s 20-30F (10-15C) above room temperature. In my 100 degree F garage, that’s 120 or so. I consider that pretty normal. Now, if it was 120F on a cool winter day, I’d be really concerned.
How hot was your garage when you measured the 110 degree temperature?

 

[Carl_P]

The Tesla mobile connector measures the temperature of the plug at the outlet; so if things get too toasty it’ll shut down or reduce power.
My mobile connector plug gets warm when charging. Without measuring it, I’d say it’s 20-30F (10-15C) above room temperature. In my 100 degree F garage, that’s 120 or so. I consider that pretty normal. Now, if it was 120F on a cool winter day, I’d be really concerned.
How hot was your garage when you measured the 110 degree temperature?

I'd say it was about 70 in there.

Note that this was the temperature AFTER he replaced the outlet with a new one. Clearly something was worse before - the wire was melted.

 

[Gauss Guzzler]

The noise and burning were because the electrician didn't tighten the screws, he just didn't want to admit it so he replaced the "faulty" receptacle.

The entire cord will get warm when charging and should feel like it's been sitting in the sun.

 

[PackMan730]

Thank you for the thoughts. Wanted to give an update on this:

I had an electrician come (the same guy that installed it). When he opened up the outlet, it was clear there was some melting of wire that had happened (you were right), as well as some burn marks on the outlet itself. However, he noted that the connection at the socket was NOT loose. He still replaced the entire outlet.

HOWEVER, after replacement of the outlet, while the charger was no longer making that crackling sound, the charging cable and EVSE were still heating up pretty good while charging. We measured temperature with a heat gun and the point of EVSE connection to the 14-50 plug head was measuring 110 degrees after charging for a bit. Also, the charging cord itself was getting somewhat hot. I am thinking there's something loose in the cable or plug now.

He didn't like this, and thought I should contact Tesla. So I am, and I have service coming tomorrow.

Do you think I need a new charging cable and EVSE, a new 14-50 plug head, or both?

How much did he charge you for this?