melting plug and recept

[raberding]

We've had a few (like 3) instances where a plug and outlet have melted, and I'm wondering why. And what we should do to prevent this in the future.
Restaurant sites and the equipment is a Warm Food Case. About 3' square, 6' tall, where food is kept warm. Specs say 29 amps, 208/1, 6-30 plug.
We specify a 30a GFCI ckt and 6-30 recept. It's thermostatically controlled.
Wondering if it's an installation issue, or should we go to a 6-50 plug/recept, staying with a 30/2 GFCI ckt.
Any thoughts are appreciated

 

[raberding]

and there are no reports of breaker tripping. GF nor Overcurrent

 

[hmspe]

What brand are the receptacles and plugs. You probably need industrial grade.

 

[hbiss]

What brand are the receptacles and plugs. You probably need industrial grade.

Could be. That's probably a regular home dryer 30A receptacle from HD. Leviton 5374 is supposed to be heavy duty industrial grade. It's important that the connections are torqued properly!

-Hal

 

[curt swartz]

30 and and 50 amp plugs and receptacles are the exact same construction.

As mentioned by other posters could be the build quality or improper torque of the connections.

 

[curt swartz]

Could be. That's probably a regular home dryer 30A receptacle from HD. Leviton 5374 is supposed to be heavy duty industrial grade. It's important that the connections are torqued properly!

-Hal

The 5374 is part of their ultra cheap designed devices. I guess Leviton pays UL $$$$$ to not loose their UL listings on their power receptacles.

 

[hbiss]

The 5374 is part of their ultra cheap designed devices.

I challenge you to find a better device by them or anybody else. That's supposed to be a heavy duty industrial grade device per their catalog. They don't even have a hospital grade 6-30. I'm not seeing anything other than that anywhere.

-Hal

 

[Little Bill]

Hubbel is usually a higher quality.

 

[hbiss]

Hubbel is usually a higher quality.

Yes, I agree. I always preferred them when $$$ was no object. But a search before made it look like Hubbell wiring devices were now being sold under the Bryant name and those didn't look much different that Leviton. Further digging shows Hubbell indeed still makes what looks like a superior 6-30. Check out the Hubbell 9330.

https://www.hubbell.com/hubbell/en/...ing-30a-250v-6-30r-black-single-pack/p/174744

-Hal

 

[BarryO]

It's important that the connections are torqued properly!

If you don't have a torque screwdriver, it's a good idea to get one.

 

[electrofelon]

I have noticed that on 10 gauge and larger sizes, the terminations frequently get loose while wrestling the device into the box. Obviously try to neatly fold in the wires as you put the device in and not just shove it in, but still I always get the device in, and then pull it out just enough to retorque.

 

[jmellc]

Hubbel is usually a higher quality.

Used to be. I had to replace a houseful of Hubbell tamper resistant receptacles. Had a Hubbell range outlet break a terminal. Worked with Hubbell wall pack lights where the plastic covers burned from heat of the lamp. A lot of their stuff is now high priced junk.

 

[raberding]

thanks for the advice gang. I realized this am that our spec is not very specific wrt manufacturer/model. We allow Cooper, Hubbell, Bryant, Leviton, and P&S.
I think I will narrow that down to Hubbell 9330 for this application. And include the 25 lb-in torque spec in our instructions.
Wondering if we should also make sure the EC uses 90°C wire...this is from the Hubbell install instructions:

 

[kwired]

30 and and 50 amp plugs and receptacles are the exact same construction.

As mentioned by other posters could be the build quality or improper torque of the connections.

Most field installed cord caps I ever seen are combo 30/50 amps. You reposition blades in the body to convert between the two ratings. And comes with an L shaped or one narrower blade depending on which configuration it is, the rest are the same thing for 30 or 50 amp rating.