MC connector

[tkb]

The Appleton 7287V 1/2" Straight Box Connector is listed for armored ground cable and NM.

https://www.platt.com/platt-electric...px?zpid=209775

There is also a 3/8" size. See page three. 7230V
http://www.emersonindustrial.com/en-...Connectors.pdf

[Brian Dang]

I also do not agree that the armor on bare armored cable even needs to be bonded.

-Hal

Don't believe in the choke effect? Remember ferrous metal -- not aluminum or copper -- is used as core for transformers. Steel metal concentrates the magnetic field (generated by the current in the GEC) and Lenz's law says the increasing magnetic flux will try to oppose the change by slowing down the current in GEC -- we call this a choking effect.

[tkb]

Don't believe in the choke effect? Remember ferrous metal -- not aluminum or copper -- is used as core for transformers. Steel metal concentrates the magnetic field (generated by the current in the GEC) and Lenz's law says the increasing magnetic flux will try to oppose the change by slowing down the current in GEC -- we call this a choking effect.

Isnt the armor touching the bare conductor for the full length?
Doesn't this have an affect on the choke?

[al hildenbrand]

Don't believe in the choke effect? Remember ferrous metal -- not aluminum or copper -- is used as core for transformers. Steel metal concentrates the magnetic field (generated by the current in the GEC) and Lenz's law says the increasing magnetic flux will try to oppose the change by slowing down the current in GEC -- we call this a choking effect.

You state the theoretical basis of the choke effect well enough.

However, we are looking at a product designed to carry an unbalanced time-varying current of significant magnitude adequate to trip service overcurrent protective devices and adequate to carry lightning to ground.

Can you point to documentation about the back-EMF choking this non-Article 320, non-Article 330 armored grounding wire?

[Brian Dang]

“However, we are looking at a product designed to carry an unbalanced time-varying current of significant magnitude adequate to trip service overcurrent protective devices and adequate to carry lightning to ground.

Can you point to documentation about the back-EMF choking this non-Article 320, non-Article 330 armored grounding wire?”

Are you asking why the Armor Grounding Wire -- a specific designed product for working as GEC – needs additional bonding at both ends? Obviously if such product already meets the code, that it is already having the conduit bonded at both ends to the inside copper conductor, then it should meet the code. But in practice I would think many cases people buy a 30 ft armor wire and only use a fraction of the length for the job, meaning they cut the cable to length, which means the cut end needs to be bonded.

Here is a good article to explain the choking effect: http://www.ecmag.com/section/codes-s...uardian-ground

“The magnetic field’s strength increases in proportion to the amount of current in the conductor. In many cases, the magnetic lines of force in the conductor are induced into the conduit enclosing the grounding electrode conductor; they can even surpass the saturation point of the steel raceway. At the point where the grounding electrode conductor exits the conduit, the magnetic lines of force generated by the fault current in the conductor will try to be induced on the end of the conduit, creating a saturation point that exceeds the conduit’s capacity. The steel conduit, in this instance, acts like a steel core of a coil to concentrate the magnetic lines of force. This condition is often referred to as the “choke effect” because it is actually the restriction of a grounding electrode conductor from performing its function. Because of this, specific bonding requirements are necessary for ferrous metal raceways that contain grounding electrode conductors. This is not a concern for grounding electrode conductors that are installed in PVC conduit or other nonferrous metal raceways such as aluminum or brass conduit.”

Lenz’s Law is a perfect tool to explain all of this, and not just for designing electric motors or generators.

Also someone asked why the ferrous metal conduit carrying a bare copper conductor inside – touching each other already – that still required to be bonded together at both ends? Touching together and measured at zero Ohms does not guarantee to have low impedance at lightning high current at frequencies of mega or giga Herzts. Think about why bonding meta raceway to enclosure using lock nut on concentric knockout is not allowed, even though it is measured with perfect zero Ohm?

[iwire]

Zero ohm?

[Brian Dang]

Well, not zero but mili ohms.

[al hildenbrand]

Are you asking why the Armor Grounding Wire -- a specific designed product for working as GEC – needs additional bonding at both ends? Obviously if such product already meets the code, that it is already having the [COLOR=#ff0000]conduit[/COLOR] bonded at both ends to the inside copper conductor, then it should meet the code. But in practice I would think many cases people buy a 30 ft armor wire and only use a fraction of the length for the job, meaning they cut the [COLOR=#FF0000]cable[/COLOR] to length, which means the cut end needs to be bonded.

Here is a good article to explain the choking effect: http://www.ecmag.com/section/codes-s...uardian-ground

“The magnetic field’s strength increases in proportion to the amount of current in the conductor. In many cases, the magnetic lines of force in the conductor are induced into the [COLOR=#ff0000]conduit[/COLOR] enclosing the grounding electrode conductor; they can even surpass the saturation point of the steel [COLOR=#ff0000]raceway[/COLOR]. At the point where the grounding electrode conductor exits the [COLOR=#ff0000]conduit[/COLOR], the magnetic lines of force generated by the fault current in the conductor will try to be induced on the end of the [COLOR=#ff0000]conduit[/COLOR], creating a saturation point that exceeds the [COLOR=#ff0000]conduit’s[/COLOR] capacity. The steel [COLOR=#ff0000]conduit[/COLOR], in this instance, acts like a steel core of a coil to concentrate the magnetic lines of force. This condition is often referred to as the “choke effect” because it is actually the restriction of a grounding electrode conductor from performing its function. Because of this, specific bonding requirements are necessary for ferrous metal [COLOR=#ff0000]raceways[/COLOR] that contain grounding electrode conductors. This is not a concern for grounding electrode conductors that are installed in PVC conduit or other nonferrous metal raceways such as aluminum or brass conduit.”

Respectfully, you are missing the point. Armored grounding wire is NOT a bare copper conductor inside a raceway (conduit).

And the listing, as KDER - Grounding and Bonding Equipment, puts it outside of Armored Cable or Metalclad Cable. So I doubt that it is even a cable.

The Code is silent about bonding the armor of Armored Grounding Wire to the wire contained in the armor.

[Brian Dang]

Respectfully, you are missing the point. Armored grounding wire is NOT a bare copper conductor inside a raceway (conduit).

And the listing, as KDER - Grounding and Bonding Equipment, puts it outside of Armored Cable or Metalclad Cable. So I doubt that it is even a cable.

The Code is silent about bonding the armor of Armored Grounding Wire to the wire contained in the armor.

I used "raceway" in a general way to describe any metal enclosure that houses one or more conductors, including RC, EMT, flex conduit, and the steel armor of the "Armor grounding wire".

What do you think the name “cable armor” below means? If it is not the specially designed single conductor enclosed by the flexible steel armor for GEC purpose that you were referring to, then what else this “cable armor” is for? It says the armor needs to be bonded (to the inside conductor).

“250.64(E) Enclosures for Grounding Electrode Conductors. Ferrous metal enclosures for grounding electrode conductors shall be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode and shall be securely fastened to the ground clamp or fitting.
Nonferrous metal enclosures shall not be required to be made electrically continuous. Ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made electrically continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor. Bonding methods in compliance with 250.92(B) for installations at service equipment locations and with 250.92(B)(2) through (B)(4) for other than service equipment locations shall apply at each end and to all intervening ferrous raceways, boxes, and enclosures between the cabinets or equipment and the grounding electrode. The bonding jumper for a grounding electrode conductor raceway or cable armor shall be the same size as, or larger than, the enclosed grounding electrode conductor.”

From link: http://www.iqelectricaltraining.com/...ed-newsletters

[al hildenbrand]

What do you think the name “cable armor” below means?

I don't think it means KDER -- Grounding and Bonding Equipment.

[al hildenbrand]

The NFPA Glossary of Terms 2014 defines "Cable" as used in NFPA 70 (the National Electrical Code) as:

A factory assembly of [COLOR=#ff0000]two or more conductors[/COLOR] having an overall covering.

Armored grounding wire is not cable.

[Brian Dang]

I don't think it means KDER -- Grounding and Bonding Equipment.

Then what do you think what else the article was talking, if not Grounding and Bonding Equipment?

[al hildenbrand]

Then what do you think what else the article was talking, if not Grounding and Bonding Equipment?

Your question was what does "cable armor" mean? . . . not what the Rule was about.

[Brian Dang]

Come on, we were discussing about the rule of bonding GEC ferrous enclosure, not the definition of cable armor. I wanted to say that the name "cable armor" in the article and your "Armor grounding wire" are interchangeable, they refer to the same device.

[al hildenbrand]

Come on, we were discussing about the rule of bonding GEC ferrous enclosure, not the definition of cable armor.

Actually, if you go back to the Opening Post (OP) and go through the first ten posts you will see that the discussion is very much about what Armored Grounding Wire actually is and where, in the Rules of the enforceable Code does and don'ts are printed.

I wanted to say that the name "cable armor" in the article and your "Armor grounding wire" [COLOR=#FF0000]are interchangeable[/COLOR], they refer to the same device.

So, you are claiming, the NFPA published definition of "cable" also includes (silently) something to the effect that any single bare conductor inside an overall outer covering is also two or more conductors. . . I suspect that this is because you "want" it to. . . not because of hard evidence of how an Armored Grounding Wire chokes unbalanced current, compared to a naked bare copper wire or compared to a bare copper wire in raceway bonded at both ends of a ferrous raceway.

Here's my point. The complete assembly of Armored Grounding Wire as a manufactured listed Category KDER product IS grounding and bonding equipment, wire AND armor. Armored Grounding Wire is manufactured to a NRTL standard, it is not field assembled by the rules of the NEC by an electrician. Any NEC rules that apply to the field assembly of a grounding wire inside an enclosure apply to a field electrician sliding the copper wire into the armor . . . the Armored Grounding Wire is assembled in a factory under a NRTL standard, not the NEC rules.