Burnt nema 14-50 plug and breaker tripped

[gh0001]

I have been using juicebox pro 40 EVSE (an older model) for my BMW i3 for two years without any problem. It’s rated 40A max on a 50A breaker.

Now I use it to charge my tesla m3 LR RWD with a J1772 adapter. I checked the charging current on tesla touchscreen and it showed that current ramping up to 40A. Seems tesla recognizes my EVSE is 40A max as it doesn’t allow me to set the max charging current to above 40A.

On my second overnight charging I received an alert from Tesla app which told me that charging was interrupted. I found that the breaker tripped and the NEMA 14-50 outlet and plug burned. See the pic below.

Does anyone have similar experience? Is there a compatibility issue with Juicebox? I am not sure if my juicebox still works - will call them on Monday.

 

[jjrandorin]

I dont believe the BMW i3 charges at the rate a tesla model 3 does. It seems to me that the higher speed a tesla is capable of charging at found an issue with either your outlet hardware, or the wiring from your panel.

I am not sure the juicebox's are UL rated either, which is one of the reasons I didnt consider that brand at all.

 

[Eno Deb]

The BMW i3 has a 7.7kW charger, i.e. at 240V it draws at most 32A. Now your Model 3 draws 40A. It seems something in your circuit didn't like that much current. Assuming the wiring has the correct gauge, most likely the outlet had a bad connection (worn out, corroded or not fully connected to the wire).

 

[Vines]

Gotta ask if the outlet was the home depot special, or the nice one that Tesla recommends? Also, do you unplug that Juicebox? Is there wear on the outlet itself?

 

[smartypnz]

I'm guessing outlet wear. The beginning Tesla S's had probs with those 14-50 outlets in that the commonly sold plugs are not designed to handle plug/unplug in frequencies for EV use. Typically, a dryer, gets plugged in once in its lifetime. So things heated up quickly - plug contacts, cables got warm to the touch. Tesla S's were trying to stay at 40 amp - a couple fires ensued - Tesla replaced the adapter with more oomph. Tesla also changed software to ramp the amps down if variations occurred.
I'm in an area where the voltage drops drastically at night so the software limits charge to 32 A. I can force it higher, but it still ramps down upon detecting variations in voltage. (Hey, it saves the garage from going up in flames and probably all of Central California Coast.)

Have an electrician survey that circuit - may be fixable. Meanwhile keep a couple bags of marshmallows on hand.

 

[gh0001]

Thanks guys. It seems that either the outlet or the juicebox plug (both burnt) can’t handle 40A. Even

I don’t think the juicebox is UL rated. As to the outlet, it was provided by the electrician. Brand is Leviton rated at 50A. Any good brand that I should use?

 

[gh0001]

Gotta ask if the outlet was the home depot special, or the nice one that Tesla recommends? Also, do you unplug that Juicebox? Is there wear on the outlet itself?

Not sure what tesla recommends. The one I had was Leviton. I did unplug the juicebox after I found the issue. Yes the outlet was damaged too.

 

[eprosenx]

I have been using juicebox pro 40 EVSE (an older model) for my BMW i3 for two years without any problem. It’s rated 40A max on a 50A breaker.

Now I use it to charge my tesla m3 LR RWD with a J1772 adapter. I checked the charging current on tesla touchscreen and it showed that current ramping up to 40A. Seems tesla recognizes my EVSE is 40A max as it doesn’t allow me to set the max charging current to above 40A.

On my second overnight charging I received an alert from Tesla app which told me that charging was interrupted. I found that the breaker tripped and the NEMA 14-50 outlet and plug burned. See the pic below.

Does anyone have similar experience? Is there a compatibility issue with Juicebox? I am not sure if my juicebox still works - will call them on Monday.

What others have said makes sense. Your previous vehicle probably did not draw as much juice. Your Tesla probably found a weakness in that receptacle/circuit.

If I had to bet, I would say the wire into the terminal on the back of the receptacle was either not torqued properly or it had some insulation pinched. I have seen a couple of these recently due to pinched insulation.

It could also be a poor quality receptacle or plug tension issue as others have suggested, though since you have a JuiceBox I am guessing you did not plug and unplug it frequently, so I doubt wear is the issue?

Also, please confirm what wire gauge the circuit is (and whether it is wire in conduit or just romex). Just want to make sure it is not the wrong gauge or something.

 

[Sparkskrd]

I have been using juicebox pro 40 EVSE (an older model) for my BMW i3 for two years without any problem. It’s rated 40A max on a 50A breaker.

Now I use it to charge my tesla m3 LR RWD with a J1772 adapter. I checked the charging current on tesla touchscreen and it showed that current ramping up to 40A. Seems tesla recognizes my EVSE is 40A max as it doesn’t allow me to set the max charging current to above 40A.

On my second overnight charging I received an alert from Tesla app which told me that charging was interrupted. I found that the breaker tripped and the NEMA 14-50 outlet and plug burned. See the pic below.

Does anyone have similar experience? Is there a compatibility issue with Juicebox? I am not sure if my juicebox still works - will call them on Monday.

 

[Sparkskrd]

I think at that Amperage itd best to hard wire don't use ,plug type, even hard wiring may have problem ,too..unless the terminal are good one , screw type, torqued down as spec..should not use Al wire , too..most of the time , the easiest is not the best way too go..too, looks like you had some high current on neutral leg, too , by looks of neutral getting hot hot too,,

 

[iluvmacs]

Regarding the comments on JuiceBox UL listing, it has been for about a year or so. Is Juicebox UL Listed or certified?

 

[gh0001]

What others have said makes sense. Your previous vehicle probably did not draw as much juice. Your Tesla probably found a weakness in that receptacle/circuit.

If I had to bet, I would say the wire into the terminal on the back of the receptacle was either not torqued properly or it had some insulation pinched. I have seen a couple of these recently due to pinched insulation.

It could also be a poor quality receptacle or plug tension issue as others have suggested, though since you have a JuiceBox I am guessing you did not plug and unplug it frequently, so I doubt wear is the issue?

Also, please confirm what wire gauge the circuit is (and whether it is wire in conduit or just romex). Just want to make sure it is not the wrong gauge or something.

Thanks. I never unplug the juicebox so it can’t be mechanical wear. Regarding the wire gauge, how can I tell? I took a pic of the wires but I can’t make sense out if it.

 

[eprosenx]

View attachment 359558

Thanks. I never unplug the juicebox so it can’t be mechanical wear. Regarding the wire gauge, how can I tell? I took a pic of the wires but I can’t make sense out if it.

The wire gauge is labeled on the wire. You may not have enough exposed to be able to read it. That looks like either 8awg or 6awg. I am guessing 8 awg. FWIW, that ground wire is oversized. 10awg is allowed for that ampacity circuit (not a problem, but just a waste).

How did the wire ends look themselves? Is the insulation melted or damaged? That white wire (which really should be red) looks gouged (though likely not your issue).

What do the ends of the wire look like where they were shoved into the terminals? Burnt? Was the clamping force onto the wire directly, or did it have any insulation pinched?

How long is the run back to the panel? Is it conduit the whole way? Is that 3/4 in conduit I assume?

8awg in conduit is code compliant for a 50a circuit (but right on the margin). Longer runs might be a good idea to do in 6awg for voltage drop reasons (but not a code issue).

It might be pretty easy to pull in new wire if you determine your wire was damaged. Could upsize it potentially depending on your goals and desires.

I have 3/4 in conduit to my wall connector and I use 6awg with a 10awg ground on a 60a circuit. I charge at 48 amps daily and it is flawless.

Oh also, it is possible that the JuiceBox whip to the plug is what failed and the issue has nothing to do with your wiring or receptacle (though the heat may have still damaged your receptacle or wires).

 

[nwdiver]

This is why I recommend charging at ~20A unless you need the faster charge. 40A generates 4x as much heat as 20A. The constant expansion and contraction can loosen the wire terminations to the outlet over time.

 

[wycolo]

Anything called 'juicebox' probably sux. HUBBELL makes the best quality outlets and switches and you pay accordingly. But if an electrical device wears out, that means it gets used a lot more than the others so deserves top quality.


> 40A generates 4x as much heat as 20A. [nwdiver]

But takes 1/2 the time . . . [ducking & running]
--

 

[jjrandorin]

Regarding the comments on JuiceBox UL listing, it has been for about a year or so. Is Juicebox UL Listed or certified?

I think it depends on which one. The 40amp one is but not the higher speed one (and I was comparing it with the Tesla Wall Connector so was looking at the higher amp one).

 

[nwdiver]

Regarding the comments on JuiceBox UL listing, it has been for about a year or so. Is Juicebox UL Listed or certified?

It's also clear that this had nothing to do with the EVSE and everything to do with the wiring at the plug.

 

[miimura]

This reminds me. It's time for my annual outlet check. I pull the socket from the wall and check the torque on all the screws holding the wires to the socket.

 

[KJD]

Not sure what tesla recommends. The one I had was Leviton. I did unplug the juicebox after I found the issue. Yes the outlet was damaged too.

Leviton is often thought of as cheap crap garbage from Home Depot and the like.

Can't seem to find the page right now, but pretty sure that Hubbell is one that Tesla recommends and yes it costs a lot more than the others.

https://www.amazon.com/Hubbell-Wiri...qid=1544395449&sr=8-3&keywords=hubbell+50+amp

 

[gh0001]

Thanks guys. Appreciated. I agree that most likely it’s because of the outlet/wiring, not the juicebox.

Pic of the outlet/receptacle above. As you can see one of terminals completely melted. The insulation of that wire was also burnt. The insulation of the white wire also showed some minor damage.

Yes the conduit runs all the way back to the panel. I think it’s either 3/4 or 7/8. I’d say it’s about 27ft.

I now need to cut back the conduit to reveal more wires for a new outlet. I hope the insulation of the wires is still visually intact once I cut them back by 3 inches. Hopefully I don’t need to re-run the whole wires?