240 volt charging wall receptacle gets very warm 14-50R bryant

[FloridaBreen]

So my 240 volt charger is plugged into a 14-50R bryant receptacle wired to the panel with 3/6 gauge and 1 8 gauge ground NMB cable to a 50 amp GE circuit breaker (about 18 inches long). My EVSE has a screen and shows data. What temps are you seeing on the receptacle? Anyone know what the mobile charger limit is before it starts to derate? (my EVSE doesn't seem to derate, so i've melted a cheapo receptacle in the past).

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[flyct]

My plug outlet connection gets heated when it’s drawing 30 amps. Try this to check if you have a loose lug. After charging for a while, shut off the breaker pull the plug out and check the temp on each individual plug blade. If you have a loose connection it will certainly heat up that blade significantly.

I know I’ve measured the breaker panel circuit breakers supplying power to my EV charger with a temp gun when charging my cars. They can get very hot to touch and I’ve measured up to 130 dF.

For a point of reference. Paper won’t ignite until it reaches 420 dF. Xerographic copiers with fuser heat rollers are set to 400 degrees.

 

[Newton]

This seems a little hot to me, you are at 50C and NM-B is rated for 60C. It is probably cold where you are now so summer might get a little closer to being a problem. However 30kW is a lot of power.

The EVSE is most likely reporting the temperature at the truck side, I don’t think that any of them measure the temperature at the receptacle side because a NMEA plug with a temp sensors in it would be hard to get. You need a heat gun (they can be cheap) to test the temperature at the outlet and at the breaker. Make sure that the breaker is tight and doesn’t wiggle. If you have melted an outlet before, contacting a good electrician would be worth it.

Turn off the power and look to see if the electrician used dialectric grease on the contacts, if not I would have some questions about the quality of the work and if the screws were properly torqued as they should be. I would also compare the voltage that you are getting at 30A with the voltage when the truck is disconnected (if possible, or when the truck is charged and not taking much power).

Hardwiring is best.

 

[flyct]

This seems a little hot to me, you are at 50C and NM-B is rated for 60C. It is probably cold where you are now so summer might get a little closer to being a problem. However 30kW is a lot of power.

The EVSE is most likely reporting the temperature at the truck side, I don’t think that any of them measure the temperature at the receptacle side because a NMEA plug with a temp sensors in it would be hard to get. You need a heat gun (they can be cheap) to test the temperature at the outlet and at the breaker. Make sure that the breaker is tight and doesn’t wiggle. If you have melted an outlet before, contacting a good electrician would be worth it.

Turn off the power and look to see if the electrician used dialectric grease on the contacts, if not I would have some questions about the quality of the work and if the screws were properly torqued as they should be. I would also compare the voltage that you are getting at 30A with the voltage when the truck is disconnected (if possible, or when the truck is charged and not taking much power).

Hardwiring is best.

Dielectric grease is an insulator, not a conductor. There is no manufacture that recommends usage of any grease or lubricant on lugs. In fact the torque specs for typical commercial 14-50 outlets made by Hubbell and Bryant are Dry Torque Specs.

The only wire connections that should have a chemical at the lugs are when using aluminum wires on lugs certified for aluminum. Then usage of something like NOALOX anti-Oxidant compound is REQUIRED. This is usually found on service entrance aluminum feeder cables.

 

[DiveMan911]

I’m having a similar issue, but on a lower amperage circuit and EVSE.

First off, it’s not my property…and an electrician just came out and wired it, so I don’t know what to think (other than I doubt it’s to code).

The outlet is a NEMA 14-30r on a 20amp circuit.
However the EVSE is a 16amp charger…pumping out a whopping 3.3kW. Simple math shows this should be around 13-14amps…well below the 80% the 20amp circuit’s maximum draw. But, the outlet and the plug on the EVSE are quite hot.

Had the truck for 2.5 years and have been on all kinds of chargers, but this is the hottest I’ve felt. Hot enough that it feels concerning.

I’ll open up the outlet and tighten lugs. Any other thoughts?

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