I thought guys might appreciate a picture of what can happen when you have a lazy outlet that does not hold a plug well. Thing is on this one it did not blow the breaker....it just kept arcing/burning until the plug lost complete contact. Of course lucky no fire occurred.

 

The pictured receptacle is actually a reasonably new, reasonably high quality style -- do you know if it had been damaged such as by someone tripping on a cord? Or perhaps more likely was a bad cord cap installation on whatever was plugged in here. That doesn't look like a factory plug.

Nonetheless, thanks for the graphical demonstration of loose connections going bad!

 

Yea, that looks more like a plug problem and not the socket. What was connected to the plug? Something that drew a lot of current?

 

What the heck is a "socket"?
*cough* Receptacle! *cough*

 

Definitely looks like a replacement plug problem rather that a receptacle failing.

Replacement plugs can be tricky to wire, and this one looks like it had solid wires attached, probably from cable such as 14-2 w/ground that is not intended to be attached to a plug.

 

A heater or hair dryer or vacuum cleaner drawing about ten amperes can burn that up in just an hour. A stereo or TV drawing 3 amps can do it too, although probably taking longer.

 

You guys all have astute observations. I'm impressed. To verify what some of you said:

--Yes it was a plug problem, not the outlet.....see scoop below. (But correct me if wrong, a lazy outlet would create same result?)
--Yes it is a high quality newer spec grade outlet....but not damaged.
--Yes it was a replacement non factory plug, but not badly wired nor with 14-2.
--Yes it drew mucho, at least 10 amps as it was plugged into a water distiller with heating element.

The official scoop is that the plug was 'partially' (not so partially it turns out) plugged in to turn off the distiller when not needed because the switch no longer worked........no I didn't do it....I aint that dumb.

 

Breakers trip on either an overload or direct short and you had neither, you just had heat from a bad connection. An AFCI breaker probably would have tripped.

 

Ya know I see disposals for instance often wired to plugs with 14-2. So as long as your workmanship is solid.....curious what might be wrong with this.?

 

Solid wire can make just a good connection with plug prongs as stranded wire. The drawback is that plugging and unplugging repeatedly will flex the cable and solid wire will break (not necessarily at the screw connection) sooner than stranded wire when flexed significantly.

Stranded wires are not immune from breaking. Actually a lot of burnups happen where the cord enters the plug especially if the appliance is plugged in and unplugged again frequently and the appliance (or something else) is pushed up against the wall with the plug almost crushed behind.

"... a plug problem, not the outlet (receptacle) ..."

Judging from the picture, by now the receptacle is also toast and must be replaced.

If the poor contact is between a plug prong and receptacle contact then damage to both will occur immediately. Even if there is still a lot of metal left when you discover and stop (arrest) the problem, the deformed, eroded, and/or otherwise damaged contact must not continue to be used.

 

A loose receptacle burning up looks a little different -- the burning tends to "hollow out" the plastic parts from the inside out, whereas yours clearly has the most burned plastic near the hot terminal of the plug. Your picture also shows no signs of heat damage to the back or side of the receptacle which is usually quite evident when the arc is happening inside the device.

Finally, aftermarket cord caps are notorious for burning up, especially when connected with solid wire which is against installation instructions and UL listing. Those should only be used with finely stranded flexible cords (SJ, etc) of a diameter and AWG specified in the instructions. Actually in my opinion that type with the screw on the blade should never be used. Instead use the ones like Leviton round style that include a screw and pressure plate to capture the wire or use a plug with crimp or solder terminals to make a permanent connection. Screw terminals cannot withstand flexible usage over time.

 

Fascinating....I never knew there were so many nuances to a replacement plug. Thanks