The History the Name Equipment Grounding Conductor

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al hildenbrand

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Does anyone know the historical traccability of the the name EGC, as well as its definition, as it has evolved in the NEC over the years.
. . . .
Is the EGC term a carry over from the days when "grounding" was the thinking of the era, with the definition changing to reflect our better understanding of its role? Or is it something different. I would be interested in the history of the term and how we got where we are today.
The Article 100 Definition of Equipment Grounding Conductor first appeared in the 1968 NEC. The 1968 NEC also included a definition for "Grounding Conductor" along side "Grounded Conductor."

"Grounding Conductor" has since been removed from Definitions.

At the beginning of the '50s, the distinctions between "grounding means", "grounded" and "grounding" was not in the Article 100 Definitions. Rather the definitions were scattered. The lead up to the 1962 NEC requirement of the EGC being at all receptacle outlets, and the subsequent confusion and education following resulted in a creating and a shaping of terms and definitions.
 

mbrooke

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You're missing the point, IMO. This is about the Equipment Grounding Conductor (EGC) which is installed as a mesh, a web, a net-like set of multiple low impedance connections that includes reference directly to Earth. The point comes when there is an absence of any low impedance EGC connection to Earth.


Ok- however I see it like this: The earth is a giant cooper ball, but every connection to it is via a 25 ohm resistor. It can be more, and there are power system out there of just two or three ground rods (1 at the pole, 2 at the service all PEX piping)


While you may have a single motor connected to Earth only by a single wire-type EGC, you cannot rule out a current loop through interconnected conductive items, all of which floats, permitting a portion of an eddy current to leave the "un-Earthed" motor body at one point and return at another. NOW, introduce a ground fault at a distant-from-the-motor chassis point, and go measure the voltage from the chassis to Earth. . . can you guarantee that resultant voltage will never be physiologically significant?

Bonding takes care of this.
 

al hildenbrand

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Electrical Contractor, Electrical Consultant, Electrical Engineer
While you may have a single motor connected to Earth only by a single wire-type EGC, you cannot rule out a current loop through interconnected conductive items, all of which floats, permitting a portion of an eddy current to leave the "un-Earthed" motor body at one point and return at another. NOW, introduce a ground fault at a distant-from-the-motor chassis point, and go measure the voltage from the chassis to Earth. . . can you guarantee that resultant voltage will never be physiologically significant?

Bonding takes care of this.

Bonding of what?

To understand the importance of Charlie's #1, you have to go back to wiring methods and practices from the first half of the Twentieth Century.

Here. I'll try again. Imagine a "First Half of the 1900s" ungrounded wiring method, in a "nonconductive" wood structure, supplying a motor. The motor is in a large apparatus that has various conductive parts that create a large electrical path to and from the motor chassis but the apparatus does not contact anything grounded to Earth. Place a gas light near the motor, a gas light on a metallic piping system not connected (bonded) to the Premises Wiring System (remember, it's the first half of the 1900s) yet delivered to the Premises via direct burial.

The conductive parts, forming the large electrical path in the apparatus, have interconnections of varying impedances having not been intended to be "electrically bonded".

Now. Establish a "ground fault" at a point on the apparatus that is "impedance-wise distant" from the motor chassis. Can you guarantee that a person touching both the motor chassis and the gas light valve will always NOT experience a physiologically significant electrical event?
 

mbrooke

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Bonding of what?

Any and all conductive objects capable of becoming faulted. Frames of appliances, conduit, ect.

To understand the importance of Charlie's #1, you have to go back to wiring methods and practices from the first half of the Twentieth Century.

Here. I'll try again. Imagine a "First Half of the 1900s" ungrounded wiring method, in a "nonconductive" wood structure, supplying a motor. The motor is in a large apparatus that has various conductive parts that create a large electrical path to and from the motor chassis but the apparatus does not contact anything grounded to Earth. Place a gas light near the motor, a gas light on a metallic piping system not connected (bonded) to the Premises Wiring System (remember, it's the first half of the 1900s) yet delivered to the Premises via direct burial.

The conductive parts, forming the large electrical path in the apparatus, have interconnections of varying impedances having not been intended to be "electrically bonded".

Now. Establish a "ground fault" at a point on the apparatus that is "impedance-wise distant" from the motor chassis. Can you guarantee that a person touching both the motor chassis and the gas light valve will always NOT experience a physiologically significant electrical event?


If you bond the gas pipe to the motor, voltage will between them will disappear- but that is not the earth doing this.
 

al hildenbrand

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Minnesota
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Electrical Contractor, Electrical Consultant, Electrical Engineer
If you bond the gas pipe to the motor, voltage will between them will disappear- but that is not the earth doing this.

OK. Then, with no ground fault on the conductive metal of the apparatus, can you guarantee that a gas pipe fitter, opening a union will never experience an electrical hazard?
 

mbrooke

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OK. Then, with no ground fault on the conductive metal of the apparatus, can you guarantee that a gas pipe fitter, opening a union will never experience an electrical hazard?

Well, I think one must ask- why don't we bond gas pipes in the US? (Yes I know CSST must be grounded)
 

romex jockey

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Vermont
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electrician
EBC?

Not all bonding is grounding,

it could simply provide equpotential between any two given objects

But all grounding is earthing

So wouldn't EC (earthing conductor) follow suit with EBC...?

(w/thanks to ResCap)

~RJ~
 
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