Hey Electricians... Can you help by proofing this new course?

[Paul W. Abernathy]

Sorry..I missed that one.....Yes, Greenfield is more a flexible metallic conduit that wires are installed into...but not generally with the wires already within it.

I am sure somewhere it may exist...but my experience with "greenfield" was that I had to pull the conductors within it....

Here is some Greenfield for ya.....

[Marcel R. Cyr]

Thanks Paul, and I found this that helps my understanding and might help others as well;

WHAT’S THE STORY?

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 Edwin 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) 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.

REPRINTED FROM AUGUST, 1986 ISSUE


ELECTRICAL CONSTRUCTION AND MAINTENANCE


@ Copyright 1986 McGraw-Hill, Inc. - All rights reserved.

VP of Product Development for AFC Cable Systems, the term "BX" stands for "Product "B" - Experimental."

Apparently, back when the product was first developed, the first manufacturer of this product had only one product at the time: "Product "A"". So when they developed this product they didn't know what to call it. Somebody suggested "Product "B" with the suffix "X" added as the product was at that time experimental.

Well, learned a little bit more today on this subject.

Marcel

[Frank P. Newman]

Armored cable (type MC) has been widely used industrial applications for many years in place of conduit and wire. There are various constructions, but in most cases there is a compelete cable assembly over which an armor of aluminum or steel is applied. The armor can either be a continuous corrugated 'tube' (CLX) or a more flexible version the has strips of metal rolled into corrugations. In many cases, an outside PVC jacket is also applied which is color-coded to signify the voltage level (typically black for 600V, yellow for 5KV and red for 15KV). Here's a picture:

[Mike Whitt]

Being that the Home Inspector is looking at buildings that were built through many decades it might be worthy to know a little history about the flexible cable with a metal covering.

Today we have two basic types of factory assembled cables and one raceway that closely resemble these. The flexible metal raceway or Greenfield as it is sometimes called is not a cable assemble so I will finish about this here.

Today we have the cables as described by Paul above.

One decade ago in the early 90s, the 1990 cycle to be exact, verbiage was added to the NEC that made it clear that MC cable was to contain an equipment grounding conductor [section 334-23] There was no mention of the EGC in the 1987 edition. The only requirement for equipment grounding was also found in 334-23 but it was worded differently, “334-23 Grounding. Type MC cable shall provide an adequate path for equipment grounding as required by Article 250.”


Verbiage found in 333-4 for type AC cable of the 1990 cycle simply stated that there shall be an internal bonding strip to intimate contact with the armor for its entire length. This is the EGC we see in today’s cable.
This verbiage concerning AC cable is unchanged from as far back as the 1962 cycle although it was found in 334-4(b). In this code cycle there is only one section titled Metal Clad Cable which covered both AC and MC.
In the 1956 cycle both was referred to as Armored Cable and was covered under 3341 and get this, it was on page 84.

This conjoining of the two (AC & MC) took place somewhere between the 1975 cycle and the 1984 cycle. I don’t have a ’78 or ’81 cycle to nail it down a little closer.
In the 1975 cycle 334-4(a) did require that type MC provide a path for grounding purposes but did not reference Article 250

I feel that this knowledge would be prudent to the Home Inspector so he now has the knowledge that until 1990 MC wasn’t required to contain any type of equipment grounding conductor but was only required to provide a grounding path as required by 250 and as little as 30 years ago didn’t even make a reference to Article 250.

As the Home Inspector goes about their duties they should understand that the standard of practice by both electricians and electrical inspectors from each time period changes.

What we are looking at sometime is not what we are seeing.

As a Home Inspector looking at a home twenty years or older unless I could visibly see an equipment grounding conductor I would not assume that the armor of any cable was the equipment grounding path. I would not trust the reading of most meters that showed a grounding path either. If a meter is reading the continuity of the armor of a cable it should also be showing the impedance of that path. The armor might have too much impedance to carry fault current but still trip out a GFCI device. Never trust the armor of a cable to be able to carry the same current as the conductors contained there in.

As Paul has pointed out above the armor of what some called “BX” will not carry the current of a fault therefore should always be called out. I also hope I have given the HI fuel for any debate they might have with any electrical contractor that might dispute them.

[Mike Whitt]

Originally Posted by jtedesco1

Mike:

Look here for the original version of this tried and true material already "in the public domain".

http://www.cdc.gov/nceh/publications...sing/cha11.htm

http://www.cdc.gov/nceh/publications...chapter_11.pdf

And for the rest of the story look here:

To order hard copies or CD-ROMs of the complete manual,
call 1-800-CDC-INFO.

Joe

Being that I am the only Mike that has responded in the thread are you addressing me?

If so please do me a favor and explain yourself a little clearer as I am nothing more than a lowly hillbilly that just don't understand.

[Marc D. Shunk]

Pictures of cute Chihuahua dogs here!

http://images.google.com/images?as_b...ua&sa=N&tab=pi

[Marcel R. Cyr]

Originally Posted by Marc D. Shunk

Pictures of cute Chihuahua dogs here!

http://images.google.com/images?as_b...ua&sa=N&tab=pi

Mark, I like the last one on the bottom right. ha. ha.

Marcel

[Nick Gromicko]

Thanks guys.

I'm looking for particular stuff found in this course already. Is any of it incorrect or deficient in any way.

Yes, we already have an Electrical Inspection course but we need to make this second one with different information in it so that we can get it state approved for CE purposes: www.nachi.org/education.htm States won't allow inspectors to earn CE for licensing purposes by repeating a course. We are making more courses in all areas (plumbing, roofing, etc.).

Anything you can do to help is appreciated.

Also, allow me to welcome Mike Whitt to InterNACHI! Welcome Mike!

Mike if you log out of the message board and then log back in using your member username and password, you will show up as a member and the other half of this message board (the members-only section) will appear to you.

[Marcel R. Cyr]

Another fine addittion to this Organization.
Welcome Mike Whitt.

Now Nick, how did you manage to do that so quickly?

I know, it must of been that story about the road kill right?

Marcel

[Kenton H. Shepard, CMI]

Today, the recommendations for grounding a home electrical system are to use two 8-foot by ⅝-inch copper ground rods. These must be spaced 6 feet apart and be connected by a continuous (unbroken) piece of copper wire"

All I can find regarding this in the IRC is E3508.4 which states that if the GE does not have a resistance of 25 ohms or less another rod is required. Who recommends this?

[Kenton H. Shepard, CMI]

I've never heard of the Local Electric Code or the Local Housing Code. Do these refer to the IRC? To local jursidictional requirements?