Hey Joe Tedesco

I am back from my vacation out west… I promised you a picture of some nice old "Armored " cable… I will post it later for you.



Pat: You mean “BX” made by the “Bronx Wire and Cable Company”?

It will probably be the “double” armor we talked about in Chicago, right?


Today’s BX and MC cable vs vintage BX Cable

Armored Cable Today:
Safe, Reliable, and Economical

by George W. Flach, Electrical Consultant, New Orleans, LA

Prevailing misconceptions about the present-day armored cable most likely stem from imperfections inherent in the original BX. Improvements made in the product are readily apparent when today’s armored cable (right) is shown side-by-side with the old BX.
Today’s armored cable, historically known as BX and more correctly as Type AC, has proved to be a safe, reliable, and economical wiring method. However, there continue to be restrictions, and sometimes prohibitions, on its use in many areas. What is behind such restrictions and are they warranted?
These restrictions on the use of armored cable, for the most part, are the result of years of misconceptions. Today, many electrical inspectors are reconsidering their position on armored cable because of its long safety record, NEC recognition, and improvements made since its introduction.
Basic armored cable was developed in the early 1900s by Harry Greenfield and Gus Johnson, who called their product BX cable. It has become a generic term for all armored cable. Some of the prevailing attitudes about the product most likely stem from imperfections inherent in the original BX.
For instance, the Type R rubber insulation used was subject to thermal-aging and cracking. The cotton-braided covering on conductors and overall braided or paper covering did little to prevent moisture damage to the insulation. When the bonding wire was finally added, it was flat and subject to breakage. In addition, it (and even the armor itself) was often mistakenly used as the neutral conductor.
The biggest problem was the lack of proper cutting tools. Old cutting methods, such as hacksaws or pliers for crimp cutting or twisting and breaking the steel armor, were very unsatisfactory and often led to nicks on the insulation and conductors, creating circuit opens or shorts.
As a result of these past deficiencies, the excellent safety record of armored cable attested to by decades of NEC recognition has been ignored. Improvements including newer, safer materials and expanded, application-oriented products, too often have gone unnoticed. The progress in the performance of armored cable is a direct result of changes made in its construction and installation techniques.


  • Insulation: The early rubber insulation has been replaced by thermoplastic insulation with excellent aging properties, thermal characteristics, and dielectric strength.
  • Wraps: Cotton braiding has been replaced with impregnated paper material that has good dielectric qualities and is moisture-resistant.
  • Anti-short bushings: Fibrous material used in early bushings has been replaced by thermoplastics that allow easy sliding and eliminate ripping, tearing, and deterioration.
  • Bonding wire: Easily breakable, flat bonding wire has been eliminated and replaced with a bonding wire that is in constant contact with the armor throughout the cable length.
  • Galvanizing: The early practice of galvanizing the sheet steel first, then cutting it into strips, left the cut edges unprotected and allowed them to rust. This technique has been di-opped in favor of galvanizing the steel after cutting, providing superior corrosion resistance.
  • *Cutting techniques:*A handheld roto-cutter (Seatek Co. Inc. pioneered the first commercially successful BX armor cable cutter in 1973. This patented tool is known as the Roto-Split](http://www.seatekco.com/rs-101a.htm))
    is now available to use in lieu of hacksaws, pliers, etc., for fast, automatically controlled cuts that significantly reduce the possibility of conductor damage.


In addition to these changes, armored cable is available now in various sizes and with multiple conductors for a variety of specialized applications, including modular wiring and fire-alarm circuitry.

Electrical inspectors in many areas of the country with strict building codes have recently begun to allow armored cable for a variety of applications when as little as two years ago some were not. Individuals such as Leo F. Martin, Deputy Commissioner for the City of Boston; Robert C. Duncan, Deputy Manager of Building and Safety for the Reedy Creek Improvement District and chairman of the Florida Chapter of the International Association of Electrical Inspectors (IAEI); and James G. Stallcup, Chief Electrical Inspector for the City of Fort Worth, TX, have rethought their positions.
Armored cable, today, is a proven and tested product with an exceptional safety record, duly recognized by the NEC and listed by independent testing laboratories. It’s an option that electrical contractors find has many advantages.
What’s the Story addresses electrical design, construction, maintenance, and equipment questions and problems. Contributed articles will be considered; comments on published articles are encouraged. Write What’s the Story, EC&M, 1221 Avenue of the Americas, New York, NY 10020.
@ Copyright 1986 McGraw-Hill, Inc. - All rights reserved.


Great info Joe,

hmmm The stuff I have looks even different then these pics.

The double spiral jacket (helical) “BX” I have looks like cloth wrapped insulation. Installed with fairly large “U” staples in the joists . I am guessing somewhere after Circa 1900’s “upgrade” in my place since gas lighting was common place. The choice of the day back then.:wink: One possible reason that “BX” was used in my area maybe due to the fact that the city limits at that time could have had different boarders. Each “community” in the greater Chicago was somewhat on it’s own set of standards with respect to materials and construction methods. After the great fire of 1871, the area in which I live in was still building with wood. That in it self was not allowed in "Chicago " proper so that lead me to believe that where I live was still considered outside the city at that time. Who knows what the regulations regarding new electrical systems installed at that time period New fangled electricity or gas light. I Still have the gas pipes in my ceiling. Disconnected of course.:wink: I found one set of cloth wrapped wires buried in a plaster wall along with the remains of a receptacle…:shock:

Pic is comming up. Need to find that old stuff in a box… Too much junk around here…:D:roll:

I found it!!

Yep it does look like the last pictures in the page of the info Joe.

Here you go. I also found some other stuff…

Does this stuff work for your collection?




Yes, thanks Pat.

A roll of 250 feet of this type of cable was very heavy. Today one could probably carry four rolls to the top floor of a building.

Does you area allow Type AC or MC Cables to be used?

I carried various (long pieces) out to the trash for the scrap guys not believing how heavy this stuff is…:o The jacket is hard to cut with the Greenfield tools… Wow, talk about a tough metal jacket… Like spring steel!

I have one run left in a section of my place left installed.

You are welcome to what I have loose ( in the picture). Let me know if you want me to ship that to you.

I am going to check the Chicago code since there are several factors in play here. Anything applies before 7-7-57 !! something about pre-ordinance residential building issues. Still trying to figure what that is all about. I thought it had to to with city hall and records being destroyed…:wink: It’s all clear as mud!

AC and MC is available in Chicago in the big box stores by the case or bundle along with empty jackets in coils for custom use. I don’t know if you can use anything beyond a 6 foot whip for applications other then lighting fixtures or FAU / Water heater connections. I will find out sooner or later.

I have seen Romex in bundles at stores in the city but it is not used in this area per some reasons. Go figure… Political pressure…hmmm Chicago… Come on…:roll: Probably the unions but that is just my guess.

Take PVC piping, another one of those Chicago deals where it was not allowed for years due to "dangerous gaseous " released in a house fire… Give me a break… A huge number of houses around here are dangerous to live in period. If your porch doesn’t collapse the lead paint, asbestos, radon, cockroaches, mold, Carbon Monoxide, plaster dust, fire trap, faulty windows, doors, electrical nightmares, slum landlords, steel security gates over your windows (can’t get out during fire) will…

Anyway I will find out and let you know…

Are there any areas around that still have NM cable installed of the older type without the EGC, or with the smaller one that was included in the cable?

I bet you can find it in some areas just outside the city far reaching limits. (Guessing here)… I need to confirm that Joe. Some local suburbs probably still have that in older homes.
I will ask a few guys around here to make sure. It all depends on how much the “City codes” passed “through” the jurisdictions surrounding the city. So many suburbs !! Many codes in the city of Chicago influenced suburban views and approaches on codes. Could be a political move or the politicians that live outside the city limits…:wink: