In a Dark Attic

[SEO]

I have run into countless electricians and inspectors that make stuff up and with a sincere sales pitch convince others of their WRONG beliefs for years.

Very well said !

 

[LarryFine]

I used to say due to high resistance, but I think someone here corrected me and said it was inductance.

It is. Or, was. The little metal strip functioned by shorting the individual turn-by-turn of the spiral wrap, and not as an obviously-undersized end-to-end EGC by itself.

 

[Pierre C Belarge]

BX, not AC cable, is one of the oldest UL Standards (#4).
AC Cable was designed and implemented (somewhere around '51) to provide a means for the metallic sheath in combination with the bond wire, of grounding purposes.

In the picture, there are both styles of cable. The left cable is the old "BX" style cable, and the cable to the right is the early version of AC Cable.

As has been mentioned in previous threads, anyone working in older buildings where the BX is installed should take heed in regards to splicing in to existing BX circuits, most likely the Effective Ground Fault Current path is not "effective" as a grounding path.

 

[iwire]

Armored Cable
Armored cable (type AC) or what it is more commonly referred to as, BX, was first listed in 1899 by the Sprague Electric Co. When it was first conceived there were two experimental versions of this product. One version was called ?AX? and the other was ?BX? with the ?X? standing for experimental. The latter or BX version was the method that eventually got produced and the name BX stuck.

Even as old as Bob is :smile:, he probably doesn;t still have his copy of the 1899 NEC to see if BX was an acceptable grounding means.

It was listed as a wiring method, I am still fairly certain it was never listed as a grounding means, I do not believe it was needed to be at that time.:smile:

 

[480sparky]

............Even as old as Bob is :smile:, he probably doesn;t still have his copy of the 1899 NEC to see if BX was an acceptable grounding means.

Just so you know, here's what the 1899 has to say about it:

 

[LarryFine]

Just so you know, here's what the 1899 has to say about it:

You couldn't show us the last paragraph under c? :roll: grin

 

[al hildenbrand]

It was listed as a wiring method, I am still fairly certain it was never listed as a grounding means, I do not believe it was needed to be at that time.:smile:

I love it when the observation puts me back in the threads of the NEC, itself, across various editions. (I know. . . it ain't natural..:wink:..)

The Twin Cities has a lot of old and new AC (think "drain wire" and "non-drain wire") scattered about and the AC is used in a great variety of installations. The patterns I've noticed, and the various AHJ opinions I've gathered in this geographic area, raised questions in my mind.

First. New in the code in 1959:

1959 NEC
Article 334 - Armored Cable
334-2. General. Armored cable for 600 volts or less shall conform to the following:
(a) Armor. All types of armored cables except Types ACL and ACV, in all sizes, shall have an internal bonding strip of either copper or aluminum in intimate contact with the armor for its entire length.

ACL is lead covered AC; and ACV is a dry location, exposed only, industrial or commercial only, not smaller than #4 type of AC.

So, garden variety AC used in branch circuits had the drain wire, by Code, from whenever the local jurisdiction adopted the 1959 NEC.

Second. From the 1953 NEC:

1953 NEC
Article 250. Grounding
Grounding Conductors
2591. Material. The material for the grounding conductor shall be as follows:
. . .
b. For Conductor Enclosures and Equipment Only. The grounding conductor for equipment and for conduit and other metal raceways or enclosures for conductors, may be a conductor of copper or other corrosion-resistant material, stranded or solid, insulated or bare, a bus-bar or a rigid conduit, steel pipe, electrical metallic tubing or the armor of armored cable, except that under conditions favorable to corrosion a grounding conductor of copper or other corrosion-resistant material shall be used.

Last. From the 1937 NEC:

1937 NEC
Article 250--Grounding
2501. General. This article treats of protection in the use of electrical circuits and equipment by grounding. Insulation, isolation, and guarding are suitable alternatives under certain conditions.
. . .
Means of Grounding
2551. General. The path to ground from circuits, equipment, or conductor enclosures shall be permanent and continuous and shall have ample carrying capacity to conduct safely any currents liable to be imposed on it, and shall have impedance sufficiently low to limit the potential above ground, and to facilitate the operation of the overcurrent devices in the circuit.
. . .
2559. Fixed Equipment. Metal boxes, cabinets and fittings, or non-current-carrying metal parts of other fixed equipment, if metallically connected to grounded cable armor or metal raceway, are considered to be grounded by such connection.
2560. Portable Equipment. Non-current-carrying metal parts of portable equipment may be grounded in any one of the following ways:
. . .
b. By means of a grounding conductor run with the circuit conductors in wire assemblies, provided an approved multi-prong plug or equivalent is used, one prong for the purpose of connecting such grounding conductor to the grounded metal raceway or cable armor. This conductor may be uninsulated but if an individual covering is provided for this conductor, it shall be finished to show a green color.

I could go on with citations from the NEC. My point is that the Code has what appears to be a long history of considering AC without a drain wire to be an effective grounding means.

I suspect that some local ordinance may exist that made exception to the NEC.

What I know from my own experience is that in normal small dwellings, the lengths of non-drain wire AC are short enough that the AHJ allows them as a "grandfathered" existing grounding means.

 

[iwire]

I love it when the observation puts me back in the threads of the NEC, itself, across various editions. (I know. . . it ain't natural..:wink:..)

:grin:

My point is that the Code has what appears to be a long history of considering AC without a drain wire to be an effective grounding means.

Well I definitely learned something today, when this has come up in the past no one was able to show that the old AC was allowed to be used for grounding.

Thanks for references and I will change my view about the history of AC I would still feel better with GFCI supplying the circuit. (Opinion, not code) :smile:

 

[al hildenbrand]

I would still feel better with GFCI supplying the circuit. (Opinion, not code) :smile:

I totally understand your opinion.

 

[480sparky]

You couldn't show us the last paragraph under c? :roll: grin

 

[Dennis Alwon]

I would like to see someone pull out those wires and install new ones. :grin:

 

[480sparky]

I would like to see someone pull out those wires and install new ones. :grin:

I'd pay a dollar for that show!

 

[dbuckley]

"...more or less grounded..." - that is a thing of beauty...

 

[charlie]

Armored Cable. Armored cable (type AC) or what it is more commonly referred to as, BX, was first listed in 1899 by the Sprague Electric Co. When it was first conceived there were two experimental versions of this product. One version was called ?AX? and the other was ?BX? with the ?X? standing for experimental. The latter or BX version was the method that eventually got produced and the name BX stuck.

Augie, where is this quoted from? I always understood that BX was from the abbreviation for Bronx.

 

[Doug S.]

That's IS a good one.

I would like to see someone pull out those wires and install new ones. :grin:

I'd pay a dollar for that show!

It's been done. They "draw" out pretty nicely after you hack up the conduits into 1' pieces. They ( meaning the local tax payers ) paid a lot more than a dollar for that job.

 

[infinity]

I love it when the observation puts me back in the threads of the NEC, itself, across various editions. (I know. . . it ain't natural..:wink:..)

The Twin Cities has a lot of old and new AC (think "drain wire" and "non-drain wire") scattered about and the AC is used in a great variety of installations. The patterns I've noticed, and the various AHJ opinions I've gathered in this geographic area, raised questions in my mind.

First. New in the code in 1959:ACL is lead covered AC; and ACV is a dry location, exposed only, industrial or commercial only, not smaller than #4 type of AC.

So, garden variety AC used in branch circuits had the drain wire, by Code, from whenever the local jurisdiction adopted the 1959 NEC.

Second. From the 1953 NEC: Last. From the 1937 NEC: I could go on with citations from the NEC. My point is that the Code has what appears to be a long history of considering AC without a drain wire to be an effective grounding means.

I suspect that some local ordinance may exist that made exception to the NEC.

What I know from my own experience is that in normal small dwellings, the lengths of non-drain wire AC are short enough that the AHJ allows them as a "grandfathered" existing grounding means.

Al excellent post.

So as I shake off my Martini fog from last evening, does this mean that prior to the installation of the bonding strip in AC cable you could use the outer jacket as an EGC?

 

[Dennis Alwon]

Al excellent post.

So as I shake off my Martini fog from last evening, does this mean that prior to the installation of the bonding strip in AC cable you could use the outer jacket as an EGC?

I believe it was allowed then problems appeared but I have not seen anything in the NEC that disallows the use of the old BX as an EGC

 

[infinity]

I believe it was allowed then problems appeared but I have not seen anything in the NEC that disallows the use of the old BX as an EGC

Back in the days of working in older houses built in the 20's, SOP was to replace old worn out two-prong receptacles with self-grounding three-prong receptacles. In some cases the HO had a two to three-prong adapter with a short wire screwed to the receptacle plate so that they could use three-prong plugs. In others they didn't connect the wire to anything. Back then the installation of a three prong self-grounding receptacle was always considered to improve the safety of the installation.

 

[SEO]

I think that the adapters created more problems than they were worth. It would be better to cut the ground prong off the attachment plug than have an install where the hot conductor faulted to the box and apply voltage thru the ground wire attached to the screw on the faceplate and end up on the equipment on the other end. A three wire receptacle on an ungrounded circuit can create the same hazzard.

 

[Dennis Alwon]

Back in the days of working in older houses built in the 20's, SOP was to replace old worn out two-prong receptacles with self-grounding three-prong receptacles. In some cases the HO had a two to three-prong adapter with a short wire screwed to the receptacle plate so that they could use three-prong plugs. In others they didn't connect the wire to anything. Back then the installation of a three prong self-grounding receptacle was always considered to improve the safety of the installation.

I agree.

Also back in the day there was often 12/2 or 14/2 nm run to the boxes with 3 wire recep. only installed in the kitchen. The rest of the house had the undersized ground with a two wire recep. I have also used the undersized ground for a 3 wire recep. figuring that's better than no ground.