Tools are Grounded to Send the surge of electricty to earth

Status
Not open for further replies.

K8MHZ

Senior Member
Why would we discuss your diagram? Where is the egc? The premise of your argument presupposes that it is convenient to install additional ground rods, yet not than the code required bonding conductors. Any of us can see that is false. You ignore any questions asked of you and only press your strawman theory forward. This is indicative of a person who is bieng intentionality obtuse.

Or, he is showing us what he is taught.

The earth connection improves service continuity and avoids damage to equipment and danger to human life.

[h=1]Indian Standard
CODE OF PRACTICE FOR EARTHING
[/h]
Obviously, we don't use the above standard in the US.

The Indian Standard is an interesting document. I just glanced through it trying to figure out why Sahib is being so adamant about his theory.

don_resqcapt19

Moderator
Staff member
Both Rart and Raux are resistances measured to remote earth. A ground fault current flowing through Rart should also flow through Raux to return to source via the grounded neutral. If Vt1 is the touch voltage at source side and Vt2, on the load side, V0 is the voltage drop along the neutral wire and Isc is the ground fault current, then

V0=Vt1+Vt2=(Isc*Rart)+(Isc*Raux)

The above equation holds not only during a ground fault but also during normal condition. To verify it, experiment with a small generator instead of POCO service for safety reasons. Ground the generator neutral and load neutral. Measure the ground resistances on each side. Load the generator and then measure the ground leakage currents in the GEC's. Also measure the voltage drop along the neutral wire. With the above data, the above equation may be verified.

Any one willing to do the above experiment?
What does the voltage drop on the neutral have to do with the touch voltage on the equipment with a fault to an ungrounded conductor.

The only change that additional grounding electrodes can make for the touch voltage where there is fault to an ungrounded conductor, is the small increase of the voltage drop on the ungrounded conductor. Even a code sized EGC does not always reduce that touch voltage to a safe level under fault conditions.

Sahib

Senior Member
What does the voltage drop on the neutral have to do with the touch voltage on the equipment with a fault to an ungrounded conductor.
Neutral in parallel with series combination of Rart and Raux.
don_resqcapt19:1749463 said:
Even a code sized EGC does not always reduce that touch voltage to a safe level under fault conditions.
That may be explained only when the above is grasped.

Last edited:

user 100

Senior Member
Why would we discuss your diagram? Where is the egc? The premise of your argument presupposes that it is convenient to install additional ground rods, yet not than the code required bonding conductors. Any of us can see that is false. You ignore any questions asked of you and only press your strawman theory forward. This is indicative of a person who is bieng intentionality obtuse.

Or, he is showing us what he is taught.

Indian Standard
CODE OF PRACTICE FOR EARTHING

Obviously, we don't use the above standard in the US.

The Indian Standard is an interesting document. I just glanced through it trying to figure out why Sahib is being so adamant about his theory.

I agree that he may be only showing what he is taught- skimmed also thru his code you posted and noticed there are some similarities w/ the NEC:

His section 7.0.2, which is titled "voltage exposure"-

"When there is unintentional contact between an electrical conductor and the metal frame or structure that encloses it (or is adjacent, the frame or structure tends to become energized to the same voltage level that exists on the energized conductor. To avoid this appearance of the dangerous, exposed shock hazard voltage, the equipment grounding conductor must present a low impedance path from the stricken frame to the the zero potential ground junction.The impedance should be sufficiently low enough to accept the full magnitude of the line to ground fault current without creating an impedance voltage drop large enough to be dangerous."

But his code also mentions RCDS( which is telling.......) and the different systems it appears they allow over there. He needs to clarify exactly which system he is talking about (tt, tn, etc) and which ocpd etc. Might help eliminate some confusion on his part.

don_resqcapt19

Moderator
Staff member
Neutral in parallel with series combination of Rart and Raux. ....
That really has nothing to do with the touch potential to earth where an ungrounded conductor has faulted to metallic equipment. The fault current is not even traveling on the grounded conductor until you get to the line side of the main bonding jumper.

Sahib

Senior Member
That really has nothing to do with the touch potential to earth where an ungrounded conductor has faulted to metallic equipment. The fault current is not even traveling on the grounded conductor until you get to the line side of the main bonding jumper.
Yes. From main jumper fault current flows in neutral wire. Measure voltage drop caused by it upto other end.

Last edited:

Sahib

Senior Member
Don: First the drawing in post 91 may be analysed whether it is correct theoretically. Then its applicability in practice may be examined.

kwired

Electron manager
Or, he is showing us what he is taught.

Indian Standard
CODE OF PRACTICE FOR EARTHING

Obviously, we don't use the above standard in the US.

The Indian Standard is an interesting document. I just glanced through it trying to figure out why Sahib is being so adamant about his theory.
I just glanced through it also and come to the conclusion that one needs to perform an installation entirely per NEC or entirely to this document. If you tried to comply with both you would have places where there is conflicts between the two standards, but follow either standard entirely and you still have a reasonably safe installation.

Not trying to say that Indian standard is bad, it just takes a different approach then the NEC does to different things. NEC has areas that IMO could be done differently, but one has to look at the big picture before making radical changes because what you do with one area can effect how things work in other areas

I see one thing that we maybe did wrong a long time ago was to use grounded conductors for normally carrying current, but how do you make such a big change considering how much 120 volt equipment is out there and the fact that most systems with 120 volts have one of the conductors of the 120 volts circuit as a grounded conductor? Eliminate current on grounded conductors and "stray voltages" are mostly left with "ground fault" conditions as the cause for stray voltages and should only exist during abnormal conditions.

Sahib

Senior Member
My discussion has no reference to Indian code, even though all utilities here follow your system permitted by Indian code.So what is wrong in post 91? or why experiment mentioned in post97 does not clarify any thing?

don_resqcapt19

Moderator
Staff member
Don: First the drawing in post 91 may be analysed whether it is correct theoretically. Then its applicability in practice may be examined.
It doesn't work because the additional grounding acts as a current divider and not as a voltage divider.

Sahib

Senior Member
It doesn't work because the additional grounding acts as a current divider and not as a voltage divider.
There are voltage drops at Rart and Raux, especially during a ground fault (Drawing at post#91). Correct?

Status
Not open for further replies.