I disconnected the cable from the wall outlet. Then I touched the cable approximately 1 inch from the short and it was quite hot to the touch. Approximately 30 seconds post disconnect, I touched the connector that a device would be connected to and it was still very hot to the touch.
Fortunately, no device was connected and nothing flammable was in proximity of the short. It is not known if there was enough heat produced to ignite a Lithium battery of a device, but I'm glad that a device was not connected for me to find out.
This is most likely the oldest and most used Apple lightning cable that we use. I suspect that the insulation surrounding Vcc and GND must have failed within the shroud, shorted producing the damaged cable. I would consider the usage for this cable to be quite normal. We do not bend it into acute angles or twist it. Simple angles and rotations to get connected to a device (iPod, iPad, or iPhone).
As an Electrical Engineer, I felt the responsibility to report this as an incident to UL since it is clearly a safety issue that could have resulted in a house fire. I'll be shipping the cable to UL in the morning for them to analyze.
If this is a failure mode that occurs after 2 to 3 years of usage, it would be very bad given the number of these cables in use with some of the first devices using these cable hitting this timeframe. If you notice a difference in the shape of the cable shroud, failure for devices to charge, or discoloration of the shroud, then stop using that cable and error on the side of safety.
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