[R-390] RE:
David Wise
[email protected]
Tue, 7 Jan 2003 10:51:22 -0800
We should probably anchor this to the National Electric Code,
if anyone has a recent copy. Mine is 1990.
Although I must confess I haven't cracked it open
for at least five years, I remember that it makes
a distinction between flexible conduit you populate
with your own wires, and the premanufactured assembly
that you cut to length and strip (aka BX). I believe
the former is called Flexible Metal Conduit and the
latter Armored Cable. FMC is permitted to function
as the Equipment Grounding Conductor, but I think you can
use a wire too if you want. I've seen AC on the shelf at the
local big home improvement place but have never used it.
For a given number and size of wires, it's much smaller than
FMC, since you don't thread wires through it. As others have
alluded, FMC or AC is required in some spots, such as going
to a motor or other assembly that might vibrate, or be taken
off its moorings for service. I used FMC+THHN from a box to
my furnace. It passed inspection.
73,
Dave Wise
> -----Original Message-----
> From: Gregory W. Moore [mailto:[email protected]]
> Sent: Monday, January 06, 2003 6:44 PM
> To: Joe Foley
> Cc: [email protected]
> Subject: Re: [R-390] RE:
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> It's called "armored cable", OR, if you just want the outside,=20
> Greenfield conduit. Leastways I have been calling it that these many=20
> years, BX went through some changes. First it was the form=20
> described by=20
> Joe, with the Paper insulation/filler. It went through some=20
> permutations=20
> of cloth, and other stuff before it wound up with the THHN.=20
> The original=20
> "Ground" was the jacket. Then, it was a miniscule (20 or more ga)=20
> aluminum wire, or a tinned copper wire. None of these "bonds" were=20
> terminated at the main junction box, they usually were (as were the=20
> original romex grounds) wrapped around the metal jacket and=20
> stuffed into=20
> the fitting, or like romex of the time, doubled back over and=20
> grounded=20
> to the clamp screw.
> Of course, the panel itself morphed, from no ground other than the=20
> service neutral, to a water pipe bond, to having the neutral=20
> and bonds=20
> on the same bus bar, to (now) having the grounding bonds on a=20
> separate=20
> bus bar. There was, in the late '70's a weird period that I=20
> would just=20
> as soon forget, when some codes wanted you to bring all the=20
> bonds back=20
> out of the panel, (yes, it was ok to bend romex bonds back=20
> over, and bx=20
> bonds the same way, wind them together, and terminate them all in=20
> either a bug, to a ground cable, leading to the rods, or a=20
> huge lug. It=20
> was really unsafe, as there was no way that one could guarantee that=20
> they all were, indeed, grounded, or any way to service this=20
> mess easily.=20
> I was glad to see that go away, but there are still huge amounts of=20
> trash wiring out there.
>=20
> Now, I did my whole basement in conduit. It looks neat, protects=20
> forever, and is easily serviced. Besides, my shack is there,=20
> and I have=20
> a 60A load center feeding that separately, which can be shut off, of=20
> course, by a safety switch outside the shack, or with a=20
> breaker at the=20
> main panel.
> 73 de Greg WA3IVX
>=20
> Joe Foley wrote:
>=20
> >Whoa, whoa, whoa, guys!
> >
> >What we have here is a failure,......... oops!
> >
> >Um, what I mean is: BX is an old term, its NOT used
> >anymore. It WAS two conductors with PAPER
> >insulation/filler inside of a "corrugated" metal
> >jacket.
> >
> >What REPLACED it and has taken on the same
> >name/identifier is, the PROPER name escapes me now
> >because I've gotten inthe habit of calling it BX, TOO!
> >
> >It is three THHN insulated wires, hot, neutral, and
> >GROUND inside the same type of metal jacket. This is
> >a much better product. Be sure to use the little red
> >anti-short bushings that come with it.
> >
> >It can also be bought with two hot wires, one black,
> >one red for three-way switches, two circuits sharing
> >the same neutral, or 240 volt applications.
> >
> >Hire an EXPERIENCED electrician! Understand: New York
> >State has NO requirement for licensing electricians,
> >if you don't believe me call the Governor's
> >office,........ hehehehehe
> >
> >Can you say BIG BEEHIVE??????
> >
> >Joe
> >
> >
> >--- Jim Brannigan <[email protected]> wrote:
> > =20
> >
> >>As I understand it, BX is required under the NYC
> >>code in order to prevent
> >>rats from eating the insulation and causing fires.
> >>
> >>In Nassau County (Long Island) BX is not required in
> >>residential
> >>installations, PVC is allowed and is rapidly
> >>replacing conduit.
> >>
> >>Jim
> >>
> >> =20
> >>
> >>>>How old are you? BX caused fires back in the
> >>>> =20
> >>>>
> >>1960s and 1970s.
> >> =20
> >>
> >>>>Well documented.
> >>>>
> >>>>
> >>>>Ken Gordon W7EKB
> >>>> =20
> >>>>
> >>>
> >>>My question ken is that if fires caused by BX are
> >>> =20
> >>>
> >>well documented
> >> =20
> >>
> >>>then why are so many commercial buildings required
> >>> =20
> >>>
> >>to use it?
> >> =20
> >>
> >>>Why do whole citys require it?
> >>>Was it an installation problem that caused the
> >>> =20
> >>>
> >>fires?
> >> =20
> >>
> >>>What was the mechanism by which the fires were
> >>> =20
> >>>
> >>caused?
> >> =20
> >>
> >>>What is different now that it does not cause
> >>> =20
> >>>
> >>fires?
> >> =20
> >>
> >>>Just trying to learn,
> >>>Scott
> >>>
> >>>
> >>>_______________________________________________
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> >>>[email protected]
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> >>> =20
> >>>
> >>_______________________________________________
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> >> =20
> >>
> >
> >
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