Why does the 14-50 plug on the mobile charger say it's only rated to 30A? The mobile charger itself pulls up to 32A and for a sustained draw that high, the lines should be rated 20% above that at 38A minimum. I'm wondering if this mis-spec is the reason this plug WAY overheated and completely melted my NEMA 14-50 outlet and nearly (I mean really nearly) started a house fire.
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Why is the Mobile Charger 14-50 plug only rated for 30A when it pulls 32A?
- Thread starter medley56
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Eric33432
Member
The plug is mis-labeled. There are other treads herein that discuss this.
What kind of receptacle melted? There are other threads herein that discuss the problems of using the cheap Leviton NEMA 14-50 receptacle that has had many reports such as yours.
stopcrazypp
Well-Known Member
If it's like practically all cases, the culprit is your outlet and your installation, not the adapter. The adapter actually has a temp sensor that the Mobile Connector uses to cut off power when it detects overheating.
A good guess is you have a Leviton outlet, which has half sized pins, so is prone to overheating (the screw based wire connection method also makes it easier for incorrect installation). I would check what outlet you have. I also would check your wires and see if they are undersized or aluminum.
If your 14-50 adapter is melted and no use anymore (it's not clear it is) then you can open it up and look at the wires and see how many AWG it is. I doubt it would be undersized, especially for such a short connection.
If you want people to do some Internet analysis, you can take some pictures of the "after" of the outlet (both the plug side as well as where the wires are connected to it) as well as the 14-50 adapter (both ends, as well as cable). But it might that analysis is worth about as much as you paid for it.
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Probably not. In virtually every case of this, its due to installation issues like loose wires, improper torque or someone installing a 14-50 outlet on wiring thats too small for it (like just connecting it to existing wiring that is the wrong gauge.
Was the outlet a Leviton 279-S00 with half size contacts to the plug blades? Melting at the front of the outlet may be the result of poor contact between the outlet and plug blades.
Melting at a back of the outlet may be the result of not-very-careful installation that results in poor contact between the wires and the outlet. Screw-down wire clamping is the norm, but requires careful installation. A few outlets (Hubbell 9450A and Bryant 9450FR) do have an improved wire clamping mechanism that is easier to install correctly.
Thanks everyone for the replies! Good to know that the plugs are just mislabeled. Do you have a source for that? I can't find one.
The electrician who came to fix this was actually the apprentice who was on site when the circuit was originally installed. He confirmed that their company no longer installs these cheap outlets for EVs (I'm guessing it was Leviton) and is being very good about using a replacement EV-rated outlet (Hubbell or Cooper). He also showed me how the wire in the back was still firmly trapped in the screw so the melting was certainly from the front of the outlet, not due to connection at the back.
The electrician who came to fix this was actually the apprentice who was on site when the circuit was originally installed. He confirmed that their company no longer installs these cheap outlets for EVs (I'm guessing it was Leviton) and is being very good about using a replacement EV-rated outlet (Hubbell or Cooper). He also showed me how the wire in the back was still firmly trapped in the screw so the melting was certainly from the front of the outlet, not due to connection at the back.
Eric33432
Member
I have no source except that Tesla is selling a NEMA 14-50 plug which ipso facto is designed for a NEMA 14-50 receptacle and is configured to tell the Tesla Mobile Connector to charge at 32 amps.
Glad to hear the problem was the cheap outlet, which is not designed for a long term load. The main use, up to EVs, for a 14-50 is for a range, which whilst a large load, is not a long load. Even if a range is in use cooking all day, the heating elements are thermostatically controlled and are not continuous loads.
Glad to hear the problem was the cheap outlet, which is not designed for a long term load. The main use, up to EVs, for a 14-50 is for a range, which whilst a large load, is not a long load. Even if a range is in use cooking all day, the heating elements are thermostatically controlled and are not continuous loads.
stopcrazypp
Well-Known Member
Here's a thread that discussed this. Basically the earlier versions were labeled 32A and later ones were changed to 30A on the label for some reason. However, there is no indication anything changed inside, and no indication any overheating came from this (rather typically it was from bad outlets or improper installation).
Note wire still in the screw does not necessarily mean proper installation, sometimes the issue is the wire was not stripped enough and some insulation was still trapped underneath the screw, which reduces the contact area and creates heat. However typically the melting would be on the back and side in those cases (not the front of the outlet).
NEMA 6-50 and 14-50 adapters are labeled 30A
stopcrazypp
Well-Known Member
Yes, lowering the amperage will reduce the risk, but if the connection is bad, it can still eventually overheat, given a lowered amperage means you are charging proportionally longer.
stopcrazypp
Well-Known Member
Verify if it is Leviton first. There are cheap outlets that are not Leviton branded that have full size contacts, so not as bad. It's possible your contractor installed one of those.
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