Think Good: Another good reason not to "back stab" receptacles. Looking close...is that a little bit of green corrosion on the black conductor??
Looks like THW insulation, metal box, so a guess it's BX. Self-grounding receptacle (look at the top yoke), appears to be "newer" as it's probably been replaced. Thinking further, the wire may have been bad, or starting when the device was replaced. Finally, the circuit may be over-fused, and/or having a "heavy" load on for extended time. (Electric heater, cooking appliances, etc)
Lastly, also could be excessive "heat" from the male attachment plug. John
I know that UL and ANSI and others work on putting the standards (minimums) together, but the guys in the field run into this all the time. I think it is time for this standard to be revisited and revised (upwards).
Re: Cooked Wires#114788 06/27/0302:41 AM06/27/0302:41 AM
This is from a neighbor's kitchen that was recently redone.
The photo didn't show the green very well, but the hot did have green on it.
The conductors were from BX. It's too late to find the conductors to check, but the insulation was thicker than what is found in Romex (Is that THHN?). There was no grounding conductor in the cable. Does that confirm THW?
P. S. If this was not in an area being renovated, assuming the overload protection was the correct rating and the device was replaced with a GFCI (as this was in a kitchen), would the BX be considered safe to use? (Does that browned area cause the whole run to be questionable?)
P. P. S. How reliable is a ground on a "self-grounding" device? The box was somewhat corroded.
Pierre: Do you mean the 75ºC rating?
[This message has been edited by ThinkGood (edited 06-27-2003).]
Re: Cooked Wires#114789 06/27/0306:00 AM06/27/0306:00 AM
I meant the 'backstabbing', what UL and manufacturers call 'pushin'. I get calls all the time relating to this. It is funny how all say they would never do this, who is doing it then? BTW - I live by the Tappen Zee Bridge, is that pretty close to you?
Re: Cooked Wires#114790 06/28/0302:27 AM06/28/0302:27 AM
Got to love those backstabbers. The insulation in the cable is most likely type TW (60°C). Type THW has a much thicker insulation, and was generally used in conduit, rather than cable. Would the green patina be from the conductor getting wet??...S
Re: Cooked Wires#114792 06/28/0306:14 AM06/28/0306:14 AM
Trumpy, "back stabbing" is when the wire is inserted into a hole in the back of the device. The electrical continuity between the conductor and the device is derived by a springy(?) clip that pushes against the wire. The connection is no where close to being as good, as the wire being under a screw. The initial result of course is heat build-up.