Few questions about grounding and bonding

[GoldDigger]

Thank you for the definitions, Smart$.

Going through them carefully confirm and support my generalized statement above:

"Bonding and Grounding are intersecting sets, not disjoint sets"

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Since we are here to learn, not to prove ourselves infallible, I welcome challengers to the statement. The code books should use that generalization since it would remove confusion for new readers such as OP.

You are assuming that the target audience is familiar with the terminology of set theory, and hopefully know what a Venn diagram is.
I think that is overly optimistic. Or overly nerdy.
Other than that I have no challenges to the statement. Just to its usefulness. It also does not explicitly remove the possibility that the two sets are in fact identical (isomorphic).

BTW, do you know what a "theomorphism" is?

 

[George Stolz]

What is system grounding, is it only taking the nuetral and bringing it to a grounding electrode?

Yes, perfect.

With the switch bonded and grounded, a hot wire hits the box, now this current going thru the box goes back to source and not the earth?

If the box gets hit by lightning, the lightning will go to earth and probably most likely also the circuit source?

If the switch box gets hit by lightning, all bets are off.

I think I understand better now. The system grounding is the grounding electrode connection to neutral to bleed overvoltage from lighting
The equipment bonding is continuity on metal parts of equipment so if the metal gets a fault the breaker will trip
Equipment grounding is sometimes a combination of grounding a bonding and is for lightning purpose ?

Check out this post and spend extra time studying 250.4(A) in your NEC and related texts.

 

[tom baker]

Most of the confusion comes from the fact that your typical EGC is serving multiple purposes: its providing a low impedance path back to source, connecting the equipment to earth, and bonding everything together. I think it would cause less confusion to call it an "equipment bonding conductor" instead of "equipment grounding conductor."

I think in my perfect world, system grounding would be pulled out into its own article, say 249, since it has nothing to do with equipment earthing and fault clearing. Then Article 250 would be called bonding, and equipment earthing and equipment bonding would be subcategories of that. There would be a statement in 250 saying that a single conductor can serve as both the equipment earthing and equipment bonding conductor. Not really sure where to stick the grounding electrode system. Probably that could get it own article, call it 248, which would further help separate earthing from fault clearing to help fight the myth. Then 249 and 250 would reference 248 as needed.

Mike Holt has said much the same about separate articles on grounding, bonding. I will say the CMP 5 has done a great job on clearing up the confusion on grounding and bonding over the last ten years.
But still, many electricians use the term ground to refer the the GEC or EGC.
In my classes I use the Pogo cartoon "we have met the enemy and he is us"
And ground is no longer a defined NEC term.

 

[m sleem]

I guess, grounding for equipment which carrying current & bonding for equipment or metals are not carrying current

 

[kwired]

I think I understand better now. The system grounding is the grounding electrode connection to neutral to bleed overvoltage from lighting
The equipment bonding is continuity on metal parts of equipment so if the metal gets a fault the breaker will trip
Equipment grounding is sometimes a combination of grounding a bonding and is for lightning purpose ?

Grounding is connecting the item to earth, or at least a reference point that is "earth equivalent" in some manner. Bonding is just insuring low resistance continuity between the items bonded. After that NEC definitions use more then one word for specific instances in an attempt to more narrowly define something. An 'equipment grounding conductor' is basically a bonding conductor, but ultimately is bonded to the grounding electrode conductor and the service grounded conductor, but doesn't have the same primary function as those others.

You are assuming that the target audience is familiar with the terminology of set theory, and hopefully know what a Venn diagram is.
I think that is overly optimistic. Or overly nerdy.
Other than that I have no challenges to the statement. Just to its usefulness. It also does not explicitly remove the possibility that the two sets are in fact identical (isomorphic).

BTW, do you know what a "theomorphism" is?

I don't know those items you mentioned, but still see that bonding conductors, grounding conductors, and grounded conductors typically intersect at some point, each segment may be serving a different primary purpose or a particular segment may be serving more then one purpose.

 

[dionysius]

I don't know those items you mentioned, but still see that bonding conductors, grounding conductors, and grounded conductors typically intersect at some point, each segment may be serving a different primary purpose or a particular segment may be serving more then one purpose.

You got it. Basic set theory is part of basic math in every high school since the 60s as I recall.