Effective ground fault path

[Djelite]

Ok we arent talking about gfci and how they work. Have a good day thanks for the chat

 

[don_resqcapt19]

Bonding is the connection of loose metal part to create an effective ground fault path along with a egc a SBJ (SDS) and a neutral wire back to the source. During the process of bonding these materials an equal potential is established

That only exists if there is no substantial current flow. Under fault conditions, different parts of the system that are connected via equipment bonding conductors and equipment grounding conductors will have potential between them and often enough to be a serious shock hazard.

 

[don_resqcapt19]

I dont think thats correct

In post 15, that the same as what you said.

 

[don_resqcapt19]

Egc provide a path to source in the event oa ground fault thru the use of a egc. Thats not the only path provided to the source and the egc function is to protect equipment for the most part. Bonding is the metallical connection of loose metal thru a mechanical means. This probably provives the best route to source and its function is to protect humans. Both are part of an effective ground falt current path to source

And both serve to protect equipment and people....there is no difference in their intended or actual function.

 

[LarryFine]

Guys, am I off the mark? Were my descriptions inaccurate?

 

[mbrooke]

Perhaps some clarification of the terms being discussed would help?

https://imgur.com/a/CWxFgui

 

[mbrooke]

Not correct. Bonding has to do with creating an equipotential environment; no voltage differences among parts, pieces, and eventually, peoples' bodies.

There are limitations to this. Bonding conductors have impedance (resistive and reactive) and such this will always result in voltage drop across the bonding grid. {Lots of copper is needed to keep this voltage drop to an acceptable voltage level}

The voltage to earth, or to the source has nothing to do with it. Think about swimming-pool equipotential bonding.

Has everything to do with it. What is the voltage outside of the pool relative to the ground one is standing on?

{We can add a copper grid in the backyard, but what about the house and front yard? We can add a copper grid to the front yard, everyone on the property is safe, but what about the potential between the side walk and yard? What about the energized mail box? Of course mesh there, but then the road, off ramp, ect}

I say this because while low impedance bonding (<0.2 ohms between nodes) brings things to the same potential, it only creates a larger zone of danger than previously existed.

The best assumption is remote earth.

 

[wwhitney]

Guys, am I off the mark? Were my descriptions inaccurate?

Only on the equipotential part--as Don points out, that's only true when no current is flowing. If a large enough voltage is imposed across two different parts of the bonding system (EGC), then current will flow according to the resistance in between, and a voltage difference will remain.

I get the impression that the OP must have a slightly different understanding of the words grounding and bonding than is typical.

Cheers, Wayne

 

[LarryFine]

Has everything to do with it. What is the voltage outside of the pool relative to the ground one is standing on?

I based that on having heard that an equipotential grid need not necessarily be connected to the equipment EGC.

Did I misunderstand that?

 

[mbrooke]

I based that on having heard that an equipotential grid need not necessarily be connected to the equipment EGC.

Did I misunderstand that?

Without a low impedance EGC, the voltage is never removed. People in the pool are safe with good bonding, anyone outside can be harmed.

 

[Djelite]

That's bonding the EGC to one of the source's conductors so OCPD open before someone is shocked. Grounding the system both creates some hazards and reduces others.

Remember, it's the EGC system that begins in the service equipment, not the (now-insulated) grounded-conductor system. That's why it's okay to use a bare neutral for bonding.

GFCI equipment depends on a grounded system to function because, while earth is not conductive to energize loads, it is conductive enough to energize

 

[ActionDave]

Guys, am I off the mark? Were my descriptions inaccurate?

Hang in there Larry. You'll get the hang of this electrical thing someday. : )

 

[paulengr]

IEEE green book talks about I think 5 or 6 different types of grounding. They are each different functions but they are all installed and operate very similarly.

System grounding and equipment grounding are already mentioned. System grounding refers to providing a fault current path. Equipment grounding has more to do with establishing equipotential conditions and it also helps with controlling common mode currents. Earth grounding is another type and as mentioned not strictly necessary. There are ungrounded systems and not just aircraft. Static electricity is another. Lightning protection another. EMF control for RF equipment and sensitive electronics is another. All behave very similarly and installation practices are pretty similar but the functions or at least purposes are different.

I learned electronics, especially radio, with a 1945 text book. I sort of learned vacuum tubes from my grandfather before transistors. I do t recall anything about Earth being a giant electron sucker or otherwise magical properties and that was in 1945. They did understand system capacitance and mirror charges.

 

[brian john]

This still doesnt answer my original question

Every metallic component is a structure between the source and fault will be a current-carrying path. Your question was answered you seem to not want to believe what has been presented.

So A better question would be what do you think the difference is in detail, how one functions differently from the other?

 

[brian john]

Every metallic component in a structure between the source and fault will be a current-carrying path. Your question was answered you seem to not want to believe what has been presented.

So A better question would be what do you think the difference is in detail, how one functions differently from the other?

Did I miss the edit button?

 

[mikeames]

Simply put IMHO to answer your question......

Because anybody who understands the semantics between EGC, GEC, bonding, and how they function does not need someone to explain one clears a fault internally and one clears a fault on conductive surfaces that would not prevent operation but would create a touch potential hazard.

For example if the metal frame of a washing machine was isolated from the motor and electrical system inside the metal frame would not need to be bonded. If a fault occurred internally on the grounded motor the breaker would trip. However if the frame were to become accidently energized from a failure in that isolation for example on the control board then the washer would continue to function but would present a hazard to people. So we bond to the frame to the EGC.

Again if you have a strong working background of EGC, bonds, and faults then its obvious. Try teaching that like that off the bat and people will be confused. I am not saying it should not be explained, I am saying its assumed once you know the difference between bonding and the EGC, you get why we bond to it.

 

[ptonsparky]

Not correct. Bonding has to do with creating an equipotential environment; no voltage differences among parts, pieces, and eventually, peoples' bodies.

The voltage to earth, or to the source has nothing to do with it. Think about swimming-pool equipotential bonding.

Yes.

Splash pads are a good example.
The rebar in the concrete and exposed metallic structures are bonded together. No bond or connection to the electrical service feeding the pumps. The bonding has virtually no function in the overcurrent or ground fault operation of CBs.

 

[Joe.B]

It also serve a path back to the source which then goes to ground

Here is the hardest misconception to unlearn, and the source of the OP's misunderstanding.

 

[gadfly56]

Just to display my ignorance, it seems to me that bonding protects against grabbing the water line and gas line while standing on a rubber mat and getting zapped, because if properly bonded there is no potential difference between them. However, if I'm in my bare feet standing on a damp concrete basement floor, I can still get shocked (or worse). If those bonded pipes are now also grounded, as in connected to to the ground bar in the panel, then I can touch those pipes in my bare feet because the potential on the pipes should have tripped the circuit breaker, assuming something like a bolted fault. I'm not so very protected if there is a high impedance fault (say, only a few hundred milliamps) and the source is not connected to a GFCI device; I'll just get equally shocked whichever pipe I grab.

 

[mikeames]

Just to display my ignorance, it seems to me that bonding protects against grabbing the water line and gas line while standing on a rubber mat and getting zapped, because if properly bonded there is no potential difference between them. However, if I'm in my bare feet standing on a damp concrete basement floor, I can still get shocked (or worse). If those bonded pipes are now also grounded, as in connected to to the ground bar in the panel, then I can touch those pipes in my bare feet because the potential on the pipes should have tripped the circuit breaker, assuming something like a bolted fault. I'm not so very protected if there is a high impedance fault (say, only a few hundred milliamps) and the source is not connected to a GFCI device; I'll just get equally shocked whichever pipe I grab.

The degree of current flow in your example above would depend on the impedance back to the utility transformer. Under normal circumstances this impedance should be very very low compared to the path impedance through you and the earth back to the utility. So yes you will be in parallel with the fault and technically some current will flow BUT it's wont be noticeable if the neutral ground bond at the main disconnect is good and the lateral back to the utility has low impedance. (Normal conditions)