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RE: All true in the perfect world of today.

Posted by Ryelands on February 11, 2017 at 10:59:57:
All true in the perfect world of today

IIRC, fuses were being used in telegraphy by the 1870s and in electrical circuits by the early 20th century. IMHO, far from being of today's perfect world, they're pretty much obsolete but that's another topic.

But what about two wire power cord and plug vintage audio equipment made before the polarized plug?

Can't off-hand comment on old kit or US rules. IIRC, UK regulations have stipulated 3-pin plugs for pretty much everything other than lighting circuits since the 1930s except for what we now call 'double insulated' devices. (What domestic users did was of course a different matter.)

In the event of an overload the fuse is still in series with the load and will blow if the load exceeds the ampere rating of the fuse

The fuse will blow (sooner or later, often considerably later) but, if the fuse is in the neutral line, the circuit remains live and thus possibly hazardous, esp if the earthing is poor.

With a 3 wire power cord . . . it could prove dangerous to the user . . . if the AC power polarity is reversed ahead of the fuse on equipment where the safety equipment ground from the wall receptacle is used.

You're right - but isn't that where I came in?

What about the incorrectly wired wall receptacle where the hot and neutral wires are reversed?

Competent electricians do not reverse polarities for well understood reasons. Incompetent electricians can be lethal.

What about the aftermarket power cord that has the hot and neutral reversed at the female IEC connector? This is more common than you would expect.

I've never bought an audio-style after-market power cord but if I did and found it was wired incorrectly I'd make the mother of a fuss.

D