[Big John]

I believe it. I once worked for an EC that charged a woman good money to have one of his guys "update" her to grounded receptacles by doing that throughout the whole house. I'm not even sure the guy who did it it knew why it was wrong.

 

[Big John]

The story doesn't state where the fault current was coming from....

It wasn't fault current, it was normal neutral current that was using the audio cable shield as a parallel path.

I've seen something very similar happen with an RS-232 connection where it actually burned up.

 

[Big John]

...I see it, but with the reversed wiring of the receptacle, the current flowing on the shield, would be what ever resistance of the shield is, no...?

No more so than current on any other wire is limited by conductor resistance. If there's enough voltage behind it, it will drive more current than the circuit can handle.

Like I said, I don't see a single thing about this that seems impossible. I've seen both the main components of that story happen under separate circumstances.

 

[Big John]

Was thinking about that this morning while going to get donuts w00t and the only part I'd like to confirm is the circuit from the grounded prong on the power supply to the shield on the communications cable.

I have some old grounded laptop supplies, and didn't see any continuity between the DC side and AC side. Further, in the laptop they'd still also have to have continuity between the DC supply and the USB port.

 

[Big John]

Why no?

Maybe you've got a really high body resistance, but if I tried that trick with a low-impedance tester it would shock me. I unfortunately know this for a fact. But the apprentice thought it was hilarious.