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We have a small counter top "turbo oven" that we've had for over 15 years. Lately the plug has been getting uncomfortably hot if the oven runs for more than 5-10 mins. Recently we were cooking something that took about 20-mins and the plug got so hot that it would almost burn your finger. Even the receptacle felt hot. Not good!

So the first thing I checked was the receptacle to ensure none of the connections have loosened. This is a dedicated 20 amp circuit containing just one receptacle. The receptacle is a high quality tight fitting commercial grade Leviton 20 amp (i.e. good ole screw connections). Everything looked good in the receptacle with no signs of excessive heat. I checked the power consumption of the oven with a Reliance power meter it draws 12 amps on high which is in agreement with what is on the electrical tag.

Next - as a test I took my 2-foot 12 gauge adapter cable from my generator and used it between the oven and the wall. This would tell me if it was the receptacle getting hot or the plug on the oven. After just a few minutes the oven plug was quite warm while the receptacle was still cool. So now I know it is the plug.

The oven has a standard molded 2-prong plug attached to a short 16 gauge cord. I cut the molded plug off and replaced it with a high quality Leviton 15 amp plug. I then ran the oven for 20-minutes and both the plug and receptacle were literally cool to the touch!

Out of curiosity I cut the molded plug apart to have a look at the connection between the wire and the prong. As you can see below, even though the male prong is a thick clean conductor the wire is attached with just a small crimp connection. This plug did not originally get this hot but I think that over time this connection loses its integrity which causes resistance and heat build up. The prong gets hot which in turns makes the receptacle get hot. If let go it would probably eventually melt the plug and bad things could follow.



I'm posting this in case someone else finds a similar situation where you have a plug getting hot for no apparent reason.
 

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Good information and thread.

Over the years, I have always tried to take care of the hot plug/receptacle issues around the house. The builder of my house probably used the least expensive receptacles all over the house, and they used the back/push in connections. At least, my house was built with copper wiring, I didn't want an aluminum wired house!

As the receptacles age, I replace them with industrial/professional grade units and always wire with the screws or screw clamps, depending on the type I buy. As for plugs, my old toaster's plug started to get warm and I changed it to an industrial Hubbell nylon plug, good screw clamp connections and tough construction ... but having that clunky extra big plug hanging off the toaster was not a popular fix in my house. The plug never got hot, but no one else appreciated the expensive quality plug I used. Ended up changing to a "unknown grade" screw terminal smaller plug, may warm up a little bit, but not hot. Anyone have suggestions on good quality smaller (usually 2 prong) plugs for small appliances? I guess I could just get a new cord set, but they probably have crimp terminals like the OP's.

As I need to replace the plugs and receptacles on my extension cords (if the cords are still in good condition), nothing beats the heavy duty nylon Hubbell's or Pass & Seymour's I've been using. I replaced the ends on some 12/3 and 10/3 generator extension cords recently, picked up some new Hubbells from fleabay for a good price.

So warm plugs and receptacles seem to be OK, but hot is not good. I searched to "normal temperature rise" for plugs and receptacles, and could not find any specific "acceptable" temperature rise. My application was a 12 amp draw for about 8 hours continuous on a 15 amp circuit, supplied by 14 AWG in house and extension cord. Anyone have information on how warm would be normal?

Just my long winded 2 cents.
 

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I guess My application was a 12 amp draw for about 8 hours continuous on a 15 amp circuit, supplied by 14 AWG in house and extension cord. Anyone have information on how warm would be normal?
Modern THHN building wire insulation is rated at 90 deg C, most devices such as cord ends and receptacles are rated at 60 deg C, and breakers and some devices are rated for 75 deg C.
If you load a device to it’s max rated amps, at say 85 deg ambient, the terminations are gonna get pretty warm—close To the 60 deg C rating.
 

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Modern THHN building wire insulation is rated at 90 deg C, most devices such as cord ends and receptacles are rated at 60 deg C, and breakers and some devices are rated for 75 deg C.
If you load a device to it’s max rated amps, at say 85 deg ambient, the terminations are gonna get pretty warm—close To the 60 deg C rating.
OK, my cord ends were not close to 60C (140F), but after changing to a new receptacle, the plug end was noticeably cooler.
 
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