John Hines wrote:

wrote:

Personally I like the dedicated equipment grounding conductor, but
then I have to remind myself, BX(AC) has a dedicated equipment
grounding conductor, and unlike romex(NM) it also shields the
conductors from accidental abuse.

BX isn't AC.

The modern AC is repeatedly referred to as BX by electricians and
electrical supply stores. I was in HD a couple of days ago and they
had a special on 250ft 12/3 ***BX***. DIY books seem to use the BX
designation more frequently than AC. Like Romex and Kleenex and Xerox,
BX was a trade name used by the inventors, GE, and referred to the
location of the plant where it was invented: the Bronx, i.e. BX.
Similarly Romex was invented (!) in Rome NY, hence the name.

BX doesn't have the grounding conductor, which means it
acts like an inductor when the cladding is used as a conductor. This is
why the bare grounding conductor was added, and the name changed to AC.

This has been discussed here many times.

To which discussions you obviously didn't pay attention. The
discussion of induced current in the spiral sheathing resulted in the
conclusion that at 60hz any induced current is infinitesimal. In
present day AC the small gauge follower wire is not the ECG and is
electrically not connected to anything except the outside sheathing.
The outside sheathing IS the ECG.

Although it's difficult to find out the exact history the consensus
seems to be that BX was introduced not primarily to prevent damage to
the conductors from nails and the like but to stop rodents gnawing on
them. The ability to use the outside sheathing as a ground was simply
serendipitous.

As to where the "induction" idea came from I heard an interesting
comment from an old guy who was certainly around at the time of the
introduction of the follower wire (early sixties). He said that the
problem with the old no-follower-wire BX was that it caused
interference with the TV sets which were becoming popular at the time.
The solution was the follower wire which stopped the spiral from
becoming an antenna. This may of course be a crock-of-****. If anyone
has any firm documented information from the era, I'd be interested in
hearing about it.